This month's news from across the specialty
What's hot
April 1, 2020
In this monthly column, members of Dermatology World's Editorial Advisory Workgroup identify exciting news from across the specialty.
Interested in some patch testing pearls for your patients with allergic contact dermatitis? In the January issue of Dialogues in Dermatology, contact dermatitis expert Ari Goldminz, MD, of Brigham and Women’s Hospital and Harvard Medical School shares with us some tips on getting the best results.
First addressing the role of immunosuppressive therapy, Dr. Goldminz reminds us that significant light exposure around the time of patch testing can significantly affect results. Patients on phototherapy need to be off of it at least a week before testing. Sunny vacations, too, can significantly alter results, and patients coming back from vacation may need to reschedule. Ideally patients would be off of medications like prednisone prior to testing, but for those patients whose disease may flare, 10mg of prednisone is Dr. Goldminz’s general threshold dose. Psoriasis biologics, like TNF alpha inhibitors, are not thought to affect results. However, the jury is still out on dupilumab.
Being familiar with the contact allergens of the year, put out by the North American Contact Dermatitis Society, can be very helpful in terms of education. For example, for those patients who think that neomycin cures everything, if you inform them that neomycin was the contact allergen of the year in 2010, they realize that it is actually a big deal! For more tips, listen to the full lecture on Dialogues in Dermatology.
An African American woman presented to her dermatologist with hair loss over her central vertex scalp. Her dermatologist’s clinical diagnosis was central centrifugal cicatricial alopecia (CCCA). However, a biopsy revealed lichen planopilaris (LPP). Based on the biopsy result, her dermatologist prescribed mycophenolate mofetil, which the patient took twice daily for over two years without any improvement. The patient’s dermatologist moved away, so the patient presented to our clinic for a refill of her mycophenolate mofetil. This case prompted me to write on this topic.
CCCA is categorized based upon the inflammatory cell infiltrate (i.e., lymphocytic, neutrophilic, mixed, and nonspecific). LPP presents with permanent hair loss, most frequently in females in young adulthood. It results in scattered foci of hair loss associated with perifollicular erythema, follicular hyperkeratosis, and scarring. There are three clinical patterns: classic LPP, Graham-Little-Piccardi Syndrome, and frontal fibrosing alopecia. CCCA most often affects middle-aged females of African descent and presents with a gradually expanding patch of permanent hair loss on the crown or vertex of the scalp.
A recent study included 51 patients — 27 with a clinical diagnosis of CCCA and 24 with LPP. All patients diagnosed with CCCA were African Americans with central scalp alopecia, while the majority of patients with LPP were Caucasian with patchy or diffuse alopecia (J Cutan Pathol. 2020;47(2):128-134).
The study found no difference in any of the histopathologic features examined and compared between the two groups. This study also established that among the immunophenotypic markers tested, there are no differences that distinguish LPP from CCCA. These findings support the view that LPP and CCCA can be differentiated by clinicopathologic correlation only.
Evaluation of leg ulcers is a common problem for physicians. Determining the etiology of a leg ulcer requires astute clinical evaluation and it can be very challenging. Biopsies are often performed, and unless there is obvious etiology such as basal cell carcinoma, the histopathologic changes may be difficult to interpret. The pathologist may see changes of vasculitis that do not truly represent vasculitis etiology.
A recent study “Histopathologic vasculitis from the periulcer edge” (J Am Acad Dermatol. 2019; 81:1353-7) examined 62 skin biopsies from patients’ leg ulcers. 52% of the specimens showed histopathologic vasculitis. While this yielded 100% sensitivity for a true underlying vasculitic process, the specificity was low at 51%. This discrepancy is likely because the edge of an ulcer shows vascular changes that can be indistinguishable from true vasculitis, including an angiocentric neutrophilic infiltrate, leukocytoclasis, endothelial swelling, fibrin and fibrinoid necrosis, and hemorrhage. This type of “reactive” vasculitis can be difficult to impossible for the pathologist to distinguish from primary vascular disease, and clinicopathologic correlation in these cases is of utmost importance.
Skin-lightening products containing mercury are illegal in the United States. But they are available — and dangerous. A recent report illustrates just how toxic these products can be (Morb Moral Wkly Rep. 2019; 68:1166-7; www.cdc.gov/mmwr/volumes/68/wr/mm6850a4.htm?s_cid=mm6850a4_w).
A 47-year-old Mexican American woman living in Sacramento, California, presented with dysesthesias and weakness of her arms. Over the next two weeks, she began experiencing dysarthria, blurry vision, and gait unsteadiness. She was hospitalized and subsequently developed agitated delirium. Two weeks after admission, screening blood and urine tests showed mercury concentrations exceeding the upper limit of quantification. The hospital notified public health authorities and initiated treatment for mercury poisoning.
A public health investigation found that the woman had been applying, twice per day for seven years, a skin-lightening cream from Mexico. An analysis showed that the cream contained 12,000 parts per million (ppm) of mercury. (The maximum allowable limit for mercury in cosmetic products, per FDA regulations, is 1 ppm). The source of the mercury in the skin-lightening cream has not been identified.
Despite treatment, the woman’s condition deteriorated. According to the report, she is unable to verbalize or care for herself and requires tube feeding for nutritional support.
Dermatologists should be aware that mercury-containing skin-lightening products exist and should counsel patients to take care when selecting and using skin-lightening products. Tips for patients on avoiding mercury-containing skin-lightening products are available from the AAD.
