July/August 2017
Volume 15 • Issue 4
Contact Dermatitis Capsule Matthew J. Zirwas, MD, Section Editor
On Lanolin Allergy and the Approach to Its Diagnosis Jonathan G. Bonchak, MD; Matthew J. Zirwas, MD
A
14-year-old boy with no significant past medical history presented with a chief complaint of a diffusely pruritic eruption for the previous several months that had begun shortly after moving to a new home on a large wooded lot (Figure). He could identify no exacerbating factors, but oral corticosteroids did provide temporary relief. The dermatitis was disabling enough that he was being bullied at school. On physical examination, there were pink-red macules, patches, and plaques with scale and excoriations, involving the face, neck, trunk, and extremities. Patch testing with the North American Contact Dermatitis Group standard series (65 allergens in total) showed a 2+ reaction to Amerchol L-101. Further questioning revealed that his parents had started a petting zoo with sheep on their new property. Avoidance of the sheep led to resolution of the previously recalcitrant dermatitis. DISCUSSION Taking a thorough history is generally considered a cornerstone in the evaluation of contact dermatitis patients. We agree; however, the time at which it is most useful to take a “thorough history” is frequently not specified. When our patch test center was established almost a decade ago, our assumption was that the history needed to be taken before patch testing to determine what allergens to use for testing. Over the ensuing years and with the experience gained through testing many thousands of patients, we eventually realized that this was not the case. The number of questions one could ask “pre-patch testing” is almost infinite, making the likelihood of asking the “right” question, even in a 40-minute visit, quite low. For instance, in this case, asking if there were exposure to a petting zoo was definitely not part of our pre-patch test history. Once we knew the patient was allergic to lanolin, inquiring about exposure to sheep
quickly led to the relevant history. The key point is that the results of patch testing allow the clinician to focus on the history and to explore the relevant exposures to the detected allergens. It is, of course, crucial that an adequate screening series, such as the American Contact Dermatitis Society Core Series, is used. Amerchol L-101 is a combination of concentrated lanolin alcohols and mineral oil used as a marker for lanolin allergy in patch testing. Lanolin, also known as wool alcohol, is a wool wax with emollient and emulsifying properties derived from the sebaceous gland secretions of sheep. It has been used by humans for centuries and functions as a vehicle in cosmetic products and medicaments applied to the skin, lips, nails, and hair.1 These products serve as the primary source of exposure in most cases of allergic contact dermatitis, although wool clothing has also been implicated.2 Lanolin is composed primarily of aliphatic alcohols and sterols. The alcohol portion has been identified as the primary sensitizing component.3 Although the composition of lanolin has been described generally, it is quite a complex substance. There are subtle component variations owing to breed and location of sheep, methods of extraction, and levels of purification.2 The variable chemical character of lanolin lends some obfuscation to its allergenic properties and our ability to reliably detect them in a clinical setting. The prevalence of positive patch test reactions to lanolin ranges from 1.6% to 4.1% based on data from large, multicenter studies.4–6 Intuitively, the prevalence is higher for subgroups in which cosmetic allergy is suspected.2,4 Counterintuitively, in the general population, men are significantly more likely to be allergic than women.2 This seems to indicate that lanolin-containing medicaments are more important sensitizers than traditional cosmetic
From the Division of Dermatology, The Ohio State University College of Medicine, Columbus, OH Address for Correspondence: Matthew J. Zirwas, MD, 540 Officenter Place, Suite 240, Gahanna, OH 43230 • E-mail: matt.zirwas@osumc.edu
SKINmed. 2017;15:289–290
289
© 2017 Pulse Marketing & Communications, LLC