A not-so-sweet diagnosis - leukocytoclastic vasculitis masquerading as squamous cell carcinoma.

Leukocytoclastic vasculitis (LCV) is a rare small-vessel vasculitis characterised by neutrophilic inflammation of post-capillary venules. Incidence varies from 3 to 4.5 per 100 000 people per year. Patients typically present with painful, itchy purpura and erythema, although clinical manifestations can vary making diagnosis a challenge. We report the case of a 75-year-old man with a history of a previously completely excised and grafted squamous cell carcinoma (SCC) on the dorsum of his hand, who presented with an acutely swollen, erythematous and ulcerated lesion adjacent to the graft site. A shave biopsy failed to definitively exclude SCC recurrence. He was referred to the Plastics team who initially suspected Sweet's syndrome but could not rule out SCC recurrence. The patient underwent formal mapping incisional biopsies that later diagnosed LCV. He was managed conservatively and made an excellent recovery. We present clinical photographs and histology to illustrate disease progression. LCV is typically self-limiting with a good overall prognosis, but a minority of patients follow a protracted course, which may require treatment in the form of systemic corticosteroids or colchicine. LCV can only be confirmed histologically. We present this case in order to highlight the importance of adequate tissue biopsy when there is diagnostic uncertainty with an acute dermatosis, particularly in the context of previous skin malignancy.