SPECIAL STAINS & IMMUNOHISTOCHEMISTRY
FRCPATH Part 1 Revision Course 2025
Nikhil Ravikumar
ST6 Histopathology
Topics we will cover
■ Mesothelioma
■ CD34
■ Cytokeratins
■ Spindle Cell Tumours
■ Bone Marrow
■ Lymphomas
■ Urology
■ Special Stains
■ Miscellaneous IHC
Recommended Supplementary Material
■ Quick Reference Guide for Surgical Pathology by Natasha Rektman
■ Pathology Outlines
■ Kurt’s Notes
■ Robbin’s / Ackermans or similar surgical pathology manual
■ Coffee!
MCQ – Question 1
A 69 year old male with a history of asbestos exposure presents with pleural effusion: The CT scan shows diffuse left sided pleural thickening.
The pleural cytology shows clusters of atypical cells with an epithelioid morphology which are immunohistochemically AE1/3 and CK7 positive, but negative for BerEP4, CEA, TTF-1, CK20, CD34 and Desmin.
The likely diagnosis is:
A. Pulmonary adenocarcinoma.
B. Malignant mesothelioma.
C. Small cell carcinoma.
D. Malignant solitary fibrous tumour.
E. Epithelioid leiomyosarcoma.
MCQ – Question 1
A 69 year old male with a history of asbestos exposure presents with pleural effusion: The CT scan shows diffuse left sided pleural thickening.
The pleural cytology shows clusters of atypical cells with an epithelioid morphology which are immunohistochemically AE1/3 and CK7 positive, but negative for BerEP4, CEA, TTF-1, CK20, CD34 and Desmin.
The likely diagnosis is:
A. Pulmonary adenocarcinoma.
B. Malignant mesothelioma.
C. Small cell carcinoma.
D. Malignant solitary fibrous tumour.
E. Epithelioid leiomyosarcoma.
Malignant Mesothelioma
■ Multiple histological subtypes and patterns
– Epithelioid, Sarcomatoid, Desmoplastic, Biphasic
■ Important Differentials:
– Epithelioid - adenocarcinoma
– Biphasic - carcinosarcoma, synovial sarcoma
– Sarcomatoid - spindle cell carcinoma, solitary fibrous tumour
– Desmoplastic - fibrous pleuritis
Malignant Mesothelioma - IHC
■ Mesothelioma
– Calretinin, CK5/6, WT-1, Thrombomodulin, D2-40 +ve
– EMA (strong membranous), p53 +ve
■ Reactive Mesothelial Proliferations
– EMA (weak membranous), p53 -ve
– BAP1 retained
■ Adenocarcinoma
– CEA, BerEp4, MOC-31 +ve
■ Cytokeratins
– MNF-116, AE1/3, EMA stain both epithelial and mesothelial cells hence cannot differentiate either
– CK5/6 +ve in squamous cell carcinoma too
■ Sarcomatoid and Desmoplastic Mesothelioma may be negative for classical mesothelioma markers
MCQ – Question 2
Which of the following tumours are CD34 positive?
A. Dermatofibrosarcoma Protuberans
B. Solitary Fibrous Tumour
C. Gastro-intestinal Stromal Tumour
D. Spindle Cell Lipoma
E. All of the above
MCQ – Question 2
Which of the following tumours are CD34 positive?
A. Dermatofibrosarcoma Protuberans
B. Solitary Fibrous Tumour
C. Gastro-intestinal Stromal Tumour
D. Spindle Cell Lipoma
E. All of the above
Dermatofibrosarcoma Protuberans (DFSP)
■ Exophytic, nodular cutaneous mass
– Slow growing then suddenly rapidly progressive
■ Monomorphic, ovoid spindle cells in a storiform (‘patternless’) pattern infiltrating the upper subcutis
– Multiple variants e.g. Melanin pigment containing – Bednar Tumour
■ COL1A1-PDGFB gene fusion product
■ t(17;22)(q22;q13) translocation
■ CD34 diffusely positive
– Can be lost if undergoing fibrosarcomatous transformation – shows a herringbone pattern in this case
■ Dermatofibroma
– CD34 +ve at periphery only or not at all
DFSP with Fibrosarcomatous Transformation
Storiform Pattern
Solitary Fibrous Tumour
■ Classically located in pleura but can be found elsewhere too
■ Slow growing and painless
■ Benign but rarely can be malignant too
■ Ovoid to fusiform spindle cells with indistinct cell borders arranged haphazardly or in short, ill-defined fascicles
■ Dilated, branching, hyalinized staghorn-like (hemangiopericytoma-like) vasculature
■ CD34 strongly diffuse positive
■ Characteristic NAB2-STAT6 fusion gene product
– +ve for STAT6 – clinches the diagnosis
■ Can also be BCL2(30%) and CD99(70%) +ve
– Non-specific
Solitary Fibrous Tumour (SFT)
Haemangiopericytic Pattern
‘Staghorn Vessels’
Fusiform Cells
GIST
■ Mesenchymal tumour derived from the interstitial cells of Cajal
■ Commonly in the stomach and small bowel
– ‘Dumbbell Tumour’
■ Bland Epithelioid, Spindle cell or mixed morphology
– Spindle cell variant has PAS+ve skenoid fibres
■ CD34, CD117 (c-kit) and DOG1 +ve
■ Treated with Tyrosine Kinase Inhibitors: Imatinib (Gleevec)
■ Syndromic associations
– Carney-Stratakis Syndrome – SDH deficient pathway
– Carney Triad
Gastro-Intestinal Stromal Tumour (GIST)
Gastro-Intestinal Stromal Tumour (GIST)
Epithelioid Subtype
Spindle Cell Lipomas
■ Affects Middle-aged men commonly on the back, shoulder, posterior neck
■ Bland spindle cells admixed with variably sized adipocytes and ‘ropey’ collagen fibres
■ Can have a myxoid stroma
■ Closely related to the Pleomorphic Lipoma
– Has pleomorphic cells and floret-like/wreath cells
– No mitotic activity
■ CD34 positive spindle cell component
■ Nuclear RB1 loss can be used in conjunction with CD34
Spindle Cell Lipomas
■ Differentials (Make sure to read about these)
– Atypical Lipomatous Tumour/Well Differentiated Liposarcoma
■ MDM2 amplification on FISH (or +ve on IHC)
– Pleomorphic Liposarcoma
■ Mitotic activity, infiltrative border
– Myxoid Liposarcoma
■ FUS-DDIT3 rearrangement
– Low grade myxofibrosarcoma
■ MUC4, BCL2 +ve, FUS-CREB3L2 rearrangement
– Myofibroblastoma
■ Desmin +ve, location and demographic different
– Schwanomma
– Neurofibroma
– DFSP
Spindle Cell Lipoma
Bland spindle cells
Ropey Collagen Adipocytes
Other CD34+ve lesions
■ Vascular tumours
– Fli-1(93% sensitive and 100% specific), CD31, CD34 and Factor VIII
– Angiosarcoma - c-myc (radiation associated)
– Epithelioid Haemangioendothelioma - CAMTA1 / YAP1
– Kaposi’s Sarcoma - HHV8
■ Acute Leukaemias - CD34 stains blasts
■ Epithelioid sarcoma – EMA/CK+, CD34+, INI1/SMARCB1 loss
MCQ – Question 3
Which of these is the most common immunophenotype of primary ovarian mucinous cystadenocarcinoma?
A. CK7 positive/CK20 negative/CAM5.2 positive
B. CK7 negative/CK20 positive/CAM5.2 positive
C. CK7 negative/CK20 negative/CAM5.2 positive
D. CK7 positive/CK20 positive/CAM5.2 positive
E. CK7 positive/CK20 positive/CAM5.2 positive
MCQ – Question 3
Which of these is the most common immunophenotype of primary ovarian mucinous cystadenocarcinoma?
A. CK7 positive/CK20 negative/CAM5.2 positive
B. CK7 negative/CK20 positive/CAM5.2 positive
C. CK7 negative/CK20 negative/CAM5.2 positive
D. CK7 positive/CK20 positive/CAM5.2 positive
E. CK7 positive/CK20 positive/CAM5.2 positive
Taken from @heartpathology twitter
Site-Specific IHC To Be Aware Of
■ TTF-1 - lung (adenocarcinoma/small cell Ca) thyroid (Pax8+), occ. in ovarian ca
■ PSA, PSAP, PSMA and P501S (Prostein), NKX3.1 - prostate
■ GCDFP-15, ER, mammaglobin, GATA-3 – breast (Pax8-)
■ CDX2 - GI tract – GEJ onwards
■ WT-1 - ovarian/peritoneal serous Ca
■ CA125 – ovarian serous and endometrioid
■ PAX-8 – all ovarian ca (87-100%) mucinous (8%)
■ Hepar1 - liver (HCC)
■ PAX-2, PAX-8, Renal cell carcinoma antigen, CD10 – Kidney tumours
■ Melan A, calretinin, inhibin, SF-1 - adrenal
MCQ – Question 4
An 80 year old man undergoes a skin excision biopsy for an ill-defined nodule on the face measuring 2cm in diameter: Histologically the epidermis is atrophic but otherwise normal. The sun-damaged dermis shows a pleomorphic spindle cell lesion with many mitotic figures, which does not extend into the subcutaneous tissue.
Immunohistochemically, the tumour cells are negative for AE1/3, MNF116, S100, smooth muscle actin and desmin.
The most likely diagnosis is:
A. Spindle cell carcinoma.
B. Synovial sarcoma
C. Cutaneous leiomyosarcoma
D. Atypical fibroxanthoma
E. Malignant melanoma.
MCQ – Question 4
An 80 year old man undergoes a skin excision biopsy for an ill-defined nodule on the face measuring 2cm in diameter: Histologically the epidermis is atrophic but otherwise normal. The sun-damaged dermis shows a pleomorphic spindle cell lesion with many mitotic figures, which does not extend into the subcutaneous tissue.
Immunohistochemically, the tumour cells are negative for AE1/AE3, MNF116, S100, smooth muscle actin and desmin.
The most likely diagnosis is:
A. Spindle cell carcinoma
B. Synovial sarcoma
C. Cutaneous leiomyosarcoma
D. Atypical fibroxanthoma
E. Malignant melanoma
Atypical Fibroxanthoma
■ Elderly person (usually male) with a scalp lesion commonly mistaken for an SCC
■ Affects sun-damaged skin on the head & neck region
■ Composed of pleomorphic, bizzare cells with frequent mitoses, limited to the dermis
– If involving Subcutis – called a Pleomorphic Dermal Sarcoma
■ Negative for cytokeratins, smooth muscle, neural and vascular markers
■ May be CD10 and CD99 positive
■ Occasional Melan-A, HMB and MiTF positivity – but not a melanoma
■ ‘Diagnosis of exclusion’
MCQ – Question 5
A 60 year-old male with pancytopenia undergoes a bone marrow trephine biopsy which shows infiltration by sheets of immature blast-like cells.
Immunohistochemically, these cells are negative for CD3, CD20 and CD138 but positive for CD117, CD34 and myeloperoxidase.
The most likely diagnosis is:
A. Classical Hodgkin’s lymphoma
B. Acute Myeloid Leukaemia
C. Diffuse Large B-cell Lymphoma
D. Plasma cell myeloma
E. Metastatic gastrointestinal stromal tumour
MCQ – Question 5
A 60 year-old male with pancytopenia undergoes a bone marrow trephine biopsy which shows infiltration by sheets of immature blast-like cells.
Immunohistochemically, these cells are negative for CD3, CD20 and CD138 but positive for CD117, CD99 and myeloperoxidase.
The most likely diagnosis is:
A. Classical Hodgkin’s lymphoma
B. Acute Myeloid Leukaemia
C. Diffuse Large B-cell Lymphoma
D. Plasma cell myeloma
E. Metastatic gastrointestinal stromal tumour
IHC for Bone Marrow Cells
■ Normal bone marrow:
– myeloperoxidase - myeloid cells
– glycophorin A - erythroid cells
– CD61 - megakaryocytes
■ Atypical cells in bone marrow
– CD3, CD5, CD43 – T cell lymphoma
– CD19, CD20, CD79, PAX5 – B cell lymphomas
– Tdt – Immature T cells
– CD34, CD117 - Myeloblasts (in AML)
– CD138, CD38 - plasma cell myeloma
– AE1/3, MNF116, cam5.2 - carcinoma mets
– TRAPP, Annexin A1 – Hairy Cell Leukaemia
■ Trephine with normal elements
■ Marrow elements replaced by sheets of blasts
CD117 (C-Kit) Positive Lesions
■ GISTs
■ Acute myeloid leukaemia
■ Seminoma
■ Melanomas
■ Mast cell neoplasms
■ Chromophobe renal cell carcinoma
■ Salivary Gland neoplasms
– Adenoid Cystic Carcinoma
– Polymorphous Adenocarcinoma
– Pleomorphic Adenoma
MCQ – Question 6
A 32 year old male undergoes an orchidectomy:
This shows a tumour composed of pleomorphic epithelioid cells forming solid papillary and glandular patterns with areas of necrosis and many mitoses.
The tumour cells are diffusely positive for AE1/3 and CD30 and show patchy positivity with placental alkaline phosphatase. They are negative for EMA and Human chorionic gonadotropin.
The most likely diagnosis is:
A. Embryonal carcinoma
B. Classical Seminoma
C. Choriocarcinoma
D. Yolk sac tumour
E. Hodgkin’s Lymphoma
MCQ – Question 6
A 32 year old male undergoes an orchidectomy:
This shows a tumour composed of pleomorphic epithelioid cells forming solid papillary and glandular patterns with areas of necrosis and many mitoses.
The tumour cells are diffusely positive for AE1/3 and CD30 and show patchy positivity with placental alkaline phosphatase. They are negative for EMA and Human chorionic gonadotropin.
The most likely diagnosis is:
B. Classical Seminoma
D. Yolk sac tumour
E. Hodgkin’s Lymphoma
A. Embryonal carcinoma
C. Choriocarcinoma
Embryonal Carcinoma
Embryonal Carcinoma
CD30 – Diffuse membranous and cytoplasmic expression
CD30 Positive Tumours
■ Embryonal carcinoma
■ Classical Hodgkin’s lymphoma
■ Anaplastic large cell lymphoma
IHC In Urological Pathology
■ Testicular tumours - PLAP, CD30, hCG, AE1/3, AFP, CD117, OCT3/4
■ Prostate - 34BE12, p63, CK5/6, Racemase, NKX3.1
■ Bladder - CK20 (carcinoma in-situ), GATA-3, uroplakin, thrombomodulin, 34BE12, p63
■ Renal tumours
– CD10, vimentin - clear cell RCC
– Racemase, CD10, CD15 - papillary RCC
– CK7 – 1>2; CK20 and E-cadherin – 2>1
– CK7, CD117 - chromophobe RCC
– 34BE12 & Racemase – Mucinous tubular and spindle cell ca
– WT-1, CD57 – Metanephric adenoma
Tumour
Oncocytoma +ve Scattered +ve cells
Chromophobe RCC +ve Diffuse, strong +ve Hale’s colloidal iron
Eosinophilic variant of Papillary RCC -ve +ve
EMQ 1 – Question 1
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
1. A 70 year old female suffering from rheumatoid arthritis for the past 20 years undergoes a renal biopsy for deranged renal function test: Extensive eosinophilic, homogenous appearing deposits are noted in the mesangium and capillary loops of the glomeruli. Serum immunoglobulins. DsDNA, ANA and ANCA titres are not raised. Serum HbA1c is within normal limits.
A. PAS with Diastase
B. Alcian Blue
D.
E. Toludine Blue
F.
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
C. Perl’s Prussian Blue
Warthin’s Starry Stain
Masson’s Trichome
EMQ 1 – Question 1
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
1. A 70 year old female suffering from rheumatoid arthritis for the past 20 years undergoes a renal biopsy for deranged renal function test: Extensive eosinophilic, homogenous appearing deposits are noted in the mesangium and capillary loops of the glomeruli. Serum immunoglobulins. DsDNA, ANA and ANCA titres are not raised. Serum HbA1c is within normal limits.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
Jones Silver
Congo Red
IF - Lambda
EMQ 1 – Question 2
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
2. A 25 year old female with multiple small yellow brown papules over the trunk and arms with a clinical suspicion of urticaria pigmentosa undergoes a skin biopsy. Histologically, nodular aggregates and sheets of mast cells and eosinophils are seen in the dermis.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
EMQ 1 – Question 2
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
2. A 25 year old female with multiple small yellow brown papules over the trunk and arms with a clinical suspicion of urticaria pigmentosa undergoes a skin biopsy. Histologically, nodular aggregates and sheets of mast cells and eosinophils are seen in the dermis.
E. Toludine Blue
H. Reticulin
I.
J.
K.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
Congo Red Stain
Von Kossa Stain
Elastic Van Gieson
Urticaria Pigmentosa (Cutaneous Mastocytosis)
Chloracetate Esterase (Leder)
Toludine Blue
EMQ 1 – Question 3
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
3. A 47 year old man undergoes a liver biopsy for mildly deranged liver function tests: The hepatocytes show prominent, brown coarse and granular cytoplasmic pigment, but no other significant abnormality.
G.
H. Reticulin
I.
D.
E. Toludine Blue
F. Masson’s Trichome
J.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
Warthin’s Starry Stain
Ziehl-Nielsson Stain
Congo Red Stain
Von Kossa Stain
K. Elastic Van Gieson
EMQ 1 – Question 3
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
3. A 47 year old man undergoes a liver biopsy for mildly deranged liver function tests: The hepatocytes show prominent, brown coarse and granular cytoplasmic pigment, but no other significant abnormality.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
EMQ 1 – Question 4
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
4. A 67 year old immuno-compromised male presents with multiple oesophageal ulcers: A biopsy shows extensive necrosis and inflammation, but no evidence of malignancy. A few possible hyphae are noted within the necrotic debris.
E.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
EMQ 1 – Question 4
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
4. A 67 year old immuno-compromised male presents with multiple oesophageal ulcers: A biopsy shows extensive necrosis and inflammation, but no evidence of malignancy. A few possible hyphae are noted within the necrotic debris.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
Gomori Silver (GMS)
EMQ 1 – Question 5
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
5. A 56 year old female with headaches undergoes a temporal artery biopsy: It shows patchy transmural inflammation.
J.
K.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
Von Kossa Stain
Elastic Van Gieson
EMQ 1 – Question 5
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
5. A 56 year old female with headaches undergoes a temporal artery biopsy: It shows patchy transmural inflammation.
A. PAS with Diastase
B. Alcian Blue
C. Perl’s Prussian Blue
D. Warthin’s Starry Stain
E. Toludine Blue
F. Masson’s Trichome
G. Ziehl-Nielsson Stain
H. Reticulin
I. Congo Red Stain
J. Von Kossa Stain
K. Elastic Van Gieson
Temporal Arteritis (Giant Cell Arteritis)
Special Stains
A. PAS with diastase - Fungi (also stain with Grocott Silver); alpha-1 anti-trypsin (A1AT) globules, glomerular basement membrane
B. Alcian Blue - Mucins (intestinal metaplasia in upper gi bx, non small cell carcinomas of lung)
C. Perl’s Prussian blue - Iron, haemosiderin, extravasated blood
D. Warthin-Starry - Spirochaetes, Bartonella (Cat-scratch disease), Helicobacter
E. Toluidine blue - Mast cells
F. Masson Trichrome - Collagen stain (collagenous colitis, fibrosis in liver/renal, crescents)
G. ZN stain/modified ZN - Acid fast bacilli (Tuberculosis Mycobacteria)
H. Reticulin - Reticulin fibres (Bone marrow fibrosis, assessing liver architecture)
I. Congo red - Amyloid
J. Von Kossa – Calcium (Michaelis-Gutman bodies in malakoplakia)
K. Elastic Van Gieson - Elastic fibres
Other Special Stains to be aware of
■ Orcein - Liver (copper associated protein, Hepatitis B surface antigen); Elastic stain
■ Victoria Blue – Liver bx essentially an Orcein substitute
■ Rhodamine – Copper in Wilson’s disease (liver bx)
■ Jones Methanamine Silver - Basement membrane (renal biopsies)
■ Gram stain – Bacteria
■ Grocott-Gomori Methanamine Silver (GMS) - Fungi
■ Chloracetate esterase (Leder Stain) - Myeloid cells, mast cells
■ Cresyl violet - Helicobacter (also can be seen with modified Giemsa)
■ Fite-Faraco – Atypical mycobacteria
■ Fontana-Masson – Melanocytes, Melanin containing cells
EMQ 2 – Question 1
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
1. A 60 year old male undergoes a bronchial biopsy: It shows infiltration by mitotically active cells with scanty cytoplasm, nuclear moulding, granular chromatin and inconspicuous nucleoli.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
EMQ 2 – Question 1
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
1. A 60 year old male undergoes a bronchial biopsy: It shows infiltration by mitotically active cells with scanty cytoplasm, nuclear moulding, granular chromatin and inconspicuous nucleoli.
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
A. Oestrogen Receptor
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
Small Cell Carcinoma
Neuroendocrine Markers
■ Synaptophysin, CD56 – more sensitive; less specific
■ Chromogranin – more specific
■ INSM1 – New marker gaining popularity
■ Not all are necessarily positive in every neuro-endocrine tumour
■ Other markers (NSE, PGP9.5)
■ CD56 also positive in myelomas, NK cell lymphomas, Rare sarcomas
■ Some carcinomas can undergo neuroendocrine differentiation as well
EMQ 2 – Question 2
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
2. A 74 year old male has a six quadrant (template) prostate core biopsy for a high PSA: One of these cores contains a cluster of small, round glands with a back to back architecture and prominent nucleoli.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
EMQ 2 – Question 2
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
2. A 74 year old male has a six quadrant (template) prostate core biopsy for a high PSA: One of these cores contains a cluster of small, round glands with a back to back architecture and prominent nucleoli.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
Basal Cell Markers - Prostate
■ 34BE12, CK5/6 (High molecular weight CKs), p63
■ Help in the detection of small foci of prostatic carcinoma and in the exclusion of benign mimics of cancer:
– Atypical Adenomatous Hyperplasia
– Partial atrophy
– Basal cell hyperplasia
– Seminal vesicle structures
Myoepithelial Markers - Breast
■ Extra-luminal Myoepithelial Cells
– p63, SMMS-1
– Invasive vs In-situ
■ Intra-Luminal Myoepithelial Cells
– CK5/6, LLO2 (CK14)
– UDH/HUT vs ADH vs DCIS
EMQ 2 – Question 3
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
3. A 52 year old woman who has MEN 2a syndrome undergoes thyroidectomy. This shows an infiltrative 3cm large tumour on slicing. Histologically, it is composed of nests of epithelioid and spindle shaped cells with fairly uniform nuclei, separated by a fibrous stroma. There is also acellular eosinophilic material seen within the tumour which appears birefringent on Congo Red staining.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
EMQ 2 – Question 3
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
3. A 52 year old woman who has MEN 2a syndrome undergoes thyroidectomy. This shows an infiltrative 3cm large tumour on slicing. Histologically, it is composed of nests of epithelioid and spindle shaped cells with fairly uniform nuclei, separated by a fibrous stroma. There is also acellular eosinophilic material seen within the tumour which appears birefringent on Congo Red staining.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
Medullary Thyroid Carcinoma
Medullary Thyroid Carcinoma
■ Composed of sheets and nests of spindle or epithelioid cells, stroma contains amyloid
■ Originates from C Cells of the thyroid
■ Association with MEN2A and MEN2B syndromes, familial medullary thyroid carcinoma (FMTC) syndrome, von Hippel-Lindau disease or neurofibromatosis
■ RET gene mutations
■ Calcitonin, CEA, chromogranin +ve
■ Thyroglobulin –ve
■ Congo Red for amyloid
– The amyloid in medullary thyroid is called Calcitonin Amyloid (ACal)
EMQ 2 – Question 4
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
4. A 72 year old female undergoes hysterectomy for an enlarged right ovarian mass: It shows a focal papillary architecture, marked nuclear pleomorphism, prominent nucleoli and psammoma bodies.
B. Thyroglobulin
D. Prostate Specific Antigen
A. Oestrogen Receptor
C. Calcitonin
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
EMQ 2 – Question 4
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
4. A 72 year old female undergoes hysterectomy for an enlarged right ovarian mass: It shows a focal papillary architecture, marked nuclear pleomorphism, prominent nucleoli and psammoma bodies.
B. Thyroglobulin
D. Prostate Specific Antigen
A. Oestrogen Receptor
C. Calcitonin
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
Ovarian High Grade Serous Adenocarcinoma
(overexpression)
EMQ 2 – Question 5
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
5. A 68 year old male undergoes an axillary lymph node biopsy for lymphadenopathy: Histology shows replacement by malignant epithelioid and spindle shaped cells with large eosinophilic nucleoli. He has history of excision of a dark skin nodule on the arm six months before.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
EMQ 2 – Question 5
In each of the following situations, select the special stain most likely to help make a definitive diagnosis:
5. A 68 year old male undergoes an axillary lymph node biopsy for lymphadenopathy: Histology shows replacement by malignant epithelioid and spindle shaped cells with large eosinophilic nucleoli. He has history of excision of a dark skin nodule on the arm six months before.
A. Oestrogen Receptor
B. Thyroglobulin
C. Calcitonin
D. Prostate Specific Antigen
E. Inhibin
F. CK7
G. CD56 (NCAM)
H. Melan-A
I. CA125
J. p63
K. WT-1
Markers of Melanocytic Differentiation
■ S100, microphthalmia transcription factor (MiTF): Sensitive, less specific
■ HMB-45, Melan A (Also known as MART1): Less sensitive, more specific (Stain lower proportion of spindle cell melanomas)
■ SOX10 – Highly specific, stain of choice for amelanotic melanomas
■ PRAME – supportive stain for assessing invasive component of melanoma –diffusely positive
■ BRAFV600E – Malignant melanocytes
EMQ 3 – Question 1
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
1. CD5 positive/CD10 negative/CD23 positive/Cyclin D1 negative/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
EMQ 3 – Question 1
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
1. CD5 positive/CD10 negative/CD23 positive/Cyclin D1 negative/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
Small Lymphocytic Lymphoma (Chronic Lymphocytic Leukaemia)
EMQ 3 – Question 2
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
2. CD5 positive/CD10 negative/CD23 negative/Cyclin D1 positive/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
EMQ 3 – Question 2
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
2. CD5 positive/CD10 negative/CD23 negative/Cyclin D1 positive/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
Mantle Cell Lymphoma
EMQ 3 – Question 3
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD5 negative/CD10 positive/Bcl-6 positive/Bcl-2 positive/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
EMQ 3 – Question 3
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD5 negative/CD10 positive/Bcl-6 positive/Bcl-2 positive/CD20 positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
Follicular Lymphoma
EMQ 3 – Question 4
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD10 positive/Bcl-6 positive/Bcl-2 negative/Ki67 100%/CD20 positive/c-myc positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
EMQ 3 – Question 4
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD10 positive/Bcl-6 positive/Bcl-2 negative/Ki67 100%/CD20 positive/c-myc positive.
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
Burkitt’s Lymphoma
EMQ 3 – Question 4
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD3 positive/CD20 negative/EMA negative/CD30 positive/Alk-1 positive
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
EMQ 3 – Question 4
For each of these, choose the category of lymphoma which best fits the immunoprofile given below:
3. CD3 positive/CD20 negative/EMA negative/CD30 positive/Alk-1 positive
A. Follicular Lymphoma
B. Anaplastic Large Cell Lymphoma
C. Classical Hodgkin’s Lymphoma
D. Marginal Zone Lymphoma
E. CLL/SLL
F. Peripheral T-Cell Lymphoma
G. T-Lymphoblastic Lymphoma
H. Burkitt’s Lymphoma
I. Angio-immunoblastic T-Cell Lymphoma
J. Mantle Cell Lymphoma
K. Nodular Lymphocyte Predominant Hodgkin’s Lymphoma
Lymphoma IHC
■ DLBCL (with double or triple hit) vs Burkitt’s Lymphoma
– Bcl-2, CD10, Bcl-6, Ki-67, C-MYC gene testing
■ Precursor B/T cell lymphomas
– TdT
■ Anaplastic large cell lymphoma
– CD3 (often negative), CD30
– ALK-1 – only in ALK+ve variant which is the most common
■ Peripheral T cell lymphoma –NOS
– CD2, CD3, CD4, CD5, CD7, CD8
■ NK cell lymphomas – CD56, CD57, TIA-1, granzyme, perforin
■ Hodgkin’s lymphoma - CD30, CD15, CD20
■ Nodular lymphocyte predominant Hodgkin lymphoma
– CD20, CD79, PAX5, OCT2, BOB1
– ‘Popcorn’/LP cells CD30 negative
EMQ 4 – Question 1
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
1. Renal angiomyolipoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
EMQ 4 – Question 1
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
1. Renal angiomyolipoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
Renal Angiomyolipoma
■ Three components
– Thick-walled Blood vessels, Adipocytes, smooth muscle
■ Co-expression of HMB45 and MelanA
■ Most common in the kidney but also occurs in the liver, lungs and other sites
■ Association with tuberous sclerosis
■ Arises from peri-vascular epithelioid cells (a family of tumours known as PEComas)
Renal Angiomyolipoma
EMQ 4 – Question 2
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
2. Endometrial stromal sarcoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
EMQ 4 – Question 2
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
2. Endometrial stromal sarcoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
Endometrial Stromal Sarcoma
■ Second most common form of uterine sarcoma
■ Typically pre to peri-menopausal women
■ Poorly circumscribed soft yellow-tan to white nodules extending from the endometrium and invading into the myometrium
■ Monotonous oval to spindle cells with minimal cytologic atypia, vesicular chromatin and scant cytoplasm
■ Most commonly bears JAZF1-SUZ12 t(7;17)(p15;q21) fusion
■ High Grade ESS can bear YWHAE-NUTM2A/B fusion or BCOR fusions
■ CD10, IFITM1, WT1, ER, PR, Pancytokeratins +ve
■ Areas of smooth muscle differentiation – SMA, Desmin, Caldesmon +ve
■ Areas of sex cord differentiation – Calretinin, MelA, Inhibin, WT1, CD99 +ve
EMQ 4 – Question 3
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
3. Langerhan’s Cell Histiocytosis
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
EMQ 4 – Question 3
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
3. Langerhan’s Cell Histiocytosis
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
Langerhans Cell Histiocytosis
■ A clonal proliferation of cells that morphologically and immunophenotypically resemble Langerhans cells
– Langerhans cells are a type of histiocytic cell which contain Birbeck granules demonstrated by EM
■ Occurs in childhood and in young males, commonly affecting bones, skin, lymph nodes and lungs
■ Pulmonary Langerhans cell histiocytosis strongly associated with smoking
– Ddx for spontaneous pneumothorax
■ Elongated cells with prominent nuclear grooves
■ Interspersed eosinophils
■ Typically positive for CD1a, Langerin and S100
Langerhans Cell Histiocytosis
S100 Positive Entities
■ Langherhans cell histiocytosis
■ Melanomas
■ Tumours of neural lineage (neurofibroma, Schwannoma, MPNST)
■ Granular cell tumours
■ Cartilagenous and adipocytic tumours
■ Myoepithelial tumours
■ Paragangliomas (sustentacular cells)
EMQ 4 – Question 4
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
4. Merkel cell carcinoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
EMQ 4 – Question 4
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
4. Merkel cell carcinoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
Merkel Cell Carcinoma
■ Commonly occurs on the sun-damaged skin of the head and neck or extremities of the elderly
■ Painless and rapidly growing flesh colored or red-violaceous nodule
■ Associated with Polyomavirus and UV exposure
■ Morphology resembles small cell carcinoma
– Nuclear moulding, speckled chromatin pattern, trabeculated architecture
■ Classical CK20 dot-like paranuclear positivity
■ Metastatic pulmonary small cell carcinoma: TTF-1, CK7 and CK20 +ve
Merkel Cell Carcinoma
EMQ 4 – Question 5
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
5. Pulmonary adenocarcinoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
EMQ 4 – Question 5
For each of the following lesions, select the antibody from the list provided, which is most likely to make the diagnosis:
5. Pulmonary adenocarcinoma.
A. HMB45
B. p53
C. CK20
D. TTF-1
E. Desmin
F. CD10
G. CD117
H. Vimentin
I. Alpha Inhibin
J. CD34
K. CD1a
L. Myeloperoxidase
Small Round Blue Cell Tumours IHC Panel
References
■ Reference slides provided by course organisers
■ Pathology Outlines
■ Webpathology
■ Kurt’s Notes
■ WHO Classification of Tumours (Online)
nikhil.ravikumar@liverpoolft.nhs.uk