Well-differentiated lipossarcoma of soft palate: case report and literature review

JULIO CLAUDIO SOUSA1 | ROGERIO COSTA TIVERON1 | RENATO QUEIROZ RAMOS1 |RENATA MARGARIDA ETCHEBEHERE1

Liposarcoma is a malignant mesenchymal tumor originating in adipose tissue cells. It occurs mainly in the extremities and retroperitoneum, but is rarely found in the head and neck region, including the oropharanyx. Thus, the objective of the present article is to presented the case report of a 27-year-old woman with a bulge in the soft palate for three years. Imaging exams showed tissue with a density compatible with fatty tissue. The lesion was removed, and the histopathology exam suggested lipoma of the soft palate. The patient missed her check-ups, and the lesion recurred three years after being removed. She again underwent surgery, and histopathology revealed a well-differentiated liposarcoma of the soft palate. Since then, the patient has maintained outpatient follow-up without evidence of recurrence. It can be concluded that, although rare in the head and neck region, liposarcoma should be considered as a possibility for lesions with a lipomatous component.

Keywords: Palate, soft. Liposarcoma. Lipoma.

1 Universidade Federal do Triângulo Mineiro, Departamento de Cirurgia, Disciplina de Otorrinolaringologia (Uberaba/MG, Brazil).

» The authors report no commercial, proprietary or financial interest in the products or companies described in this article.

» Patients displayed in this article previously approved the use of their facial and intraoral photographs. How to cite: Sousa JC, Tiveron RC, Ramos RQ, Etchebehere RM. Well-differentiated lipossarcoma of soft palate: case report and literature review. J Braz Coll Oral Maxillofac Surg. 2021 JanApr;7(1):55-60. DOI: https://doi.org/10.14436/2358-2782.7.1.055-060.oar

Submitted: July 18, 2018 - Revised and accepted: March 06, 2019

Contact address: Julio Claudio Sousa E-mail: jcotorrino@gmail.com

The liposarcoma, described by Virchow in 1857, is a malignant mesenchymal tumor originating from fat tissue cells. It represents approximately 17 to 30% of all soft tissue sarcomas.1 These tumors occur predominantly in the limbs and retroperitoneum and in middle-aged adults, being rare in the head and neck region, especially in the oropharynx.2 In general, sarcomas represent only 1% of primary head and neck tumors.3 A comprehensive literature review demonstrated that soft palate liposarcoma is extremely rare, limited to occasional reports. The objectives of the present case report were to present the occurrence of this rare well-differentiated soft palate liposarcoma and present a literature review, regarding the diagnosis, treatment and prognosis of this pathology.

Female patient aged 27 years, Caucasoid, without clinical history, attended the Otolaryngology service in July 2009 due to a complaint of bulging in the soft palate for approximately three years, associated with nasal obstruction and dysphagia for liquid and solid foods. The general physical examination did not show abnormalities. During otolaryngological examination, a volumetric increase in the soft palate was observed, predominantly to the left, with soft consistency, undefined limits, painless on palpation and lined by mucosa with normal aspect (Fig 1).

The cervical tomography in coronal section, showed a grossly ovoid expansive lesion with well-defined limits and fat density, dimensions of 5x5 cm, with epicenter located on the left lateral wall of the oropharynx (Fig 2). Cervical resonance showed an expansive lesion, measuring 6 x 5.5 x 3.5 cm, located close to the posterior and left lateral walls of the oropharynx, grossly ovoid, with well-defined limits, similar signal as fat tissue in all study sequences, without significant post-contrast enhancement (Fig 3). Based on the clinical characteristics of the lesion and imaging findings, a clinical hypothesis of soft palate lipoma was made, and the patient underwent general anesthesia with transoral excision of the lesion from a paramedian incision on the soft palate. The lesion was enucleated without difficulty, measuring 7 x 5 x 3 cm. The postoperative period was uneventful. The patient was discharged one day after surgery with good velopharyngeal function. The histopathological result revealed lipoma of the soft palate.

The patient missed the outpatient follow-up consultations, returning in June 2013, complaining of a new bulging in the soft palate for one year, with rapid evolution in the last four months. At the time, she complained of intense dysphagia and weight loss. Otolaryngological examination evidenced a large bulging of the soft palate. The patient underwent a new transoral excision of the lesion. Again, surgery was uneventful, and the lesion measured 7 x 5.5 x 3.5 cm. The histopathology of this second approach revealed a well-differentiated liposarcoma, with surgical margins coinciding with the pseudocapsule (Fig 4). Despite this coincidence, it was decided not to perform adjuvant radiotherapy.

Since reoperation, i.e., 5 years ago, the patient has maintained the outpatient follow-up, without evidence of new relapse (Fig 5).

Figure 1: Volumetric increase of the soft palate. Figure 2: 2D computed tomography (coronal section) showing an expansive well-defined lesion with fat density, located on the soft palate.

Figure 3: T1-weighted coronal plane MRI showing expansive ovoid lesion, defined limits at the transition between naso- and oropharynx, with homogeneous hypersignal and fine interspersed trabeculae.

Figure 4: Mesenchymal neoplasm composed of mature adipocytes permeated by rare lipoblasts (hematoxylin-eosin, 400X).

Figure 5: T1-weighted MRI, coronal plane, showing soft palate with no changes in the late postoperative period.

Liposarcomas of the head and neck are rare, representing 5 to 9% of all liposarcomas.2 Specifically concerning the topography of the oropharynx, the incidence of liposarcomas is extremely rare, being limited to isolated case reports. During the present literature review in the PubMed database, using the keywords liposarcoma, oropharynx and soft palate, only four cases were found reported in the last ten years.

The histological classification of liposarcomas has changed over the decades. The need for universal standardization gave rise to the classification of the World Health Organization in 2002. Advances in genetic and molecular research revealed that liposarcoma corresponds to a heterogeneous group of tumors, consisting of five histological types: well-differentiated, myxoid, round cells, pleomorphic and undifferentiated.4 Well-differentiated and myxoid tumors are considered low-grade lesions, with less aggressive behavior and characterized by usually local relapse with rare metastases. However, pleomorphic, round cell and undifferentiated types are considered high-grade lesions and thus exhibit more aggressive behavior. The well-differentiated subtype represents the most frequent liposarcoma, accounting for about 40 to 45% of all liposarcomas.5 The outstanding histological characteristics that allow the diagnosis of well-differentiated liposarcoma are: variation in adipocyte size, adipocytes with atypical, enlarged and hyperchromatic nucleus and bizarre stromal cells, frequent in fibrous septa, between adipocytes and also in vessel walls. The histological evaluation of head and neck tumors with a lipomatous component requires differential diagnosis with fatty necrosis, silicone granuloma and benign tumors with an adipocytic component.2

In many cases, the differentiation between a benign adipocytic tumor and a well-differentiated liposarcoma can be extremely difficult. Thus, cytogenetic evaluation can have a valuable contribution, since well-differentiated liposarcoma has peculiar chromosomal changes that differentiate it from lipoma.6

Liposarcomas usually manifest as a slow-growing, painless tumor. Subsequent signs and symptoms result from the affected region and possibility of involvement of neurovascular structures. Less frequently, these lesions present with rapid, aggressive growth, invading locally and originating metastases to the lung, brain, liver, kidney and spine.3,7 In the present case, the patient had oropharyngeal dysphagia and nasal obstruction.

During imaging examination, the identification of fatty tissue inside the lesion represents the critical point in the suspicion of a lipomatous tumor. The careful evaluation of images, besides raising the hypothesis of lipomatous tumor, allows accuracy as to the lesion location, local extent and relationship with adjacent structures. Large and heterogeneous lesions, in deep location and rapidly growing are usually associated with an increased risk of malignancy. Tomography and magnetic resonance imaging are highlighted in the investigation of expansive lesions in the head and neck region. The distinction between liposarcoma and lipoma is often a diagnostic dilemma, especially in small lesions. In magnetic resonance imaging, the most relevant findings to differentiate liposarcoma from lipoma are: presence of septa with thickening greater than 2 mm, nodular or globular areas of non-adipocytic tissue inside or adjacent to the lesion, and amount of non-adipocytic tissue greater than 25% of the lesion.8

In the present case, lipoma was the initial clinical diagnosis, considering the duration, surface and consistency of the lesion. Imaging findings also did not suggest liposarcoma.

The most effective treatment for liposarcoma is complete surgical excision, with free margins. However, in the head and neck region, the extent of resection must consider the possibility of functional losses and the proximity to important neurovascular structures. Since incomplete resection increases the possibility of relapse, postoperative radiotherapy may be necessary for selected cases, especially those in which total excision was not possible.3,4,9 For liposarcomas of the head and neck, factors as more superficial lesions, smaller dimensions and myxoid and well-differentiated histological subtypes indicate good prognosis. Also, when compared to other anatomical sites, liposarcomas of the head and neck show less aggressive behavior and thus have a better prognosis.3,9

Though rare in the head and neck region, liposarcoma should be considered as a differential diagnosis of lesions with lipomatous component. Complete surgical excision with an adequate margin represents the treatment of choice, and postoperative radiotherapy is an alternative for selected cases. Due to the possibility of relapse, extended postoperative follow-up is necessary.

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