Clinicopathologic analysis of atypical hand, foot, and mouth disease in adult patients.

Background: Hand, foot, and mouth disease is a contagious viral infection usually affecting children. A resurgence of cases in adults, mainly caused by coxsackievirus A6 and with an atypical and more severe presentation, has taken place.

Objective: The goal was to examine the clinical, histologic, and immunohistochemical features of this disease in adults.

Methods: This is a retrospective study on documented cases of adult hand, foot, and mouth disease from France's Dermatology Department of Strasbourg University Hospital and Bel-Air Hospital in Thionville.

Results: Six patients with severe and atypical presentation were included, 4 caused by coxsackievirus A6. The histologic features were: spongiosis, neutrophilic exocytosis, massive keratinocyte necrosis, shadow cells in the upper epidermis, vacuolization of basal cells, necrotic cells in follicles and sweat glands, dense superficial dermal infiltrate of CD3 lymphocytes, and strong granulysin expression.

Limitations: This is a retrospective case series.

Conclusion: In adult patients presenting with atypical hand, foot, and mouth disease caused by coxsackievirus A6, biopsy specimens show distinctive changes in the epidermis but also in adnexal structures. The inflammatory infiltrate is made of T cells with a cytotoxic profile, with numerous granulysin-positive cells, as observed in severe drug-induced eruption with necrosis of keratinocytes.