P021 Plasma-cell dermatomucositis: a new face of cocaine toxicity

Abstract

Cocaine-associated plasma cell orifical dermatomucositis (PCOD) is a novel clinical entity, first described in 2023. We describe two cases presenting to a single UK centre to further characterize this emerging condition. Patient 1 is a 47-year-old man referred with a 3-month history of a rapidly enlarging, tender lesion on the left side of the philtrum. Patient 2 is a 46-year-old man managed by dermatology for eczema who reported a 4-month history of a rapidly enlarging granulating plaque on the philtrum. Differential diagnoses for both lesions included squamous cell carcinoma, pyogenic granuloma, infections (including syphilis) and granulomatosis with polyangiitis. Incisional biopsies were performed in both cases. Biopsy in case 1 demonstrated ulceration with a dense interstitial and perivascular dermal plasma-cell infiltrate. Eosinophils were also present. In case 2, biopsy showed irregular acanthosis, foci of ulceration with numerous plasma cells, and eosinophils in granulation tissue at the base of the ulcer. Notably both patients reported intranasal cocaine use one to five times per week. Following exclusion of differentials, the diagnosis of cocaine-associated PCOD was made. Cocaine and levamisole, its main adulterant, are associated with primarily neutrophilic disorders and immune-mediated conditions. Cocaine-associated PCOD appears to be an emerging clinical entity, with classical lesions affecting the nasal vestibule, nostril and philtrum. Histopathology demonstrates a dense dermal plasma-cell infiltrate, without a primary vasculitis or granulomas. Treatments suggested include corticosteroids and systemic immunosuppressants. Both cases were treated with oral prednisolone, resulting in improvement but not resolution. PCOD is an emerging clinical entity distinct from the vasculitic and neutrophilic patterns classically associated with cocaine use. The cause is unclear but it may be related to a newly introduced substance in the cutting process. These cases highlight the importance of enquiring regarding cocaine use when patients present with suspicious lesions, as cessation of cocaine use is necessary for resolution.