CPC05 A case of Gianotti–Crosti syndrome secondary to mpox

Abstract

A 44-year-old man presented to the emergency department with a 5-day history of anal pain, rectal bleeding, perineal pain, dysuria and pain on ejaculation. He also reported a rash affecting the hands and back. He denied systemic, abdominal or testicular symptoms. A trial of topical haemorrhoid cream provided no relief. A screen for sexually transmitted infections performed the previous day was negative, although he was empirically started on aciclovir for presumed herpes infection. His past medical history included asthma and Hodgkin lymphoma treated with two stem cell transplants. He reported regular unprotected sexual activity with a male partner and was taking HIV pre-exposure prophylaxis. On examination, there were scattered pustular lesions on his hands, buttocks and penis, along with erythema over the buttocks and condylomatous-appearing lesions. Punch biopsies were taken from two sites. Histology from the dorsal index finger demonstrated a mixed spongiotic, lichenoid and perivascular dermatitis pattern, consistent with Gianotti–Crosti syndrome, while a perianal biopsy showed ulceration, necrosis and mixed inflammation suggestive of orthopoxvirus infection, confirmed by positive mpox polymerase chain reaction swab. Mpox is an orthopoxvirus infection that was first reported in humans in 1970. There are two principal strains (clades), with clade IIb mpox gaining global clinical recognition during the major global outbreak in 2022. Mpox can present with general ‘flu-like’ symptoms, including fever, headache, malaise, body aches and lymphadenopathy. Although the characteristic dermatological features include umbilicated vesicles, pustules, pseudopustules and erosions, emerging evidence suggests mpox can present with atypical cutaneous manifestations, particularly in immunocompromised individuals. Gianotti–Crosti syndrome (or papular acrodermatitis of childhood) is a benign, self-limiting papular rash seen in children that is often secondary to a viral infection. To the authors’ knowledge, this is the first reported case of mpox-associated papular acrodermatitis seen in an immunocompromised man who has sex with men.