Necrotizing panniculitis secondary to primary cutaneous localized mucormycosis

Abstract

Primary cutaneous mucormycosis is a rare entity that affects more frequently extremities of immunosuppressed patients and may be gradual in onset or fulminant. An 83-year-old female with diabetes mellitus presented a nodular lesion in the forearm, which had progressed during one month. Clinically, as the lesion was indolent and followed a linear trajectory, a superficial phlebitis was suspected but later ruled out. Skin blood cultures were negative. Skin biopsy showed a necrotic panniculitis with isolated ghost adipocytes and presence of irregularly branched hyphae involving dermis and some vessels that could be stained with PAS and Grocott, thus leading to the diagnosis of primary cutaneous localized mucormycosis. This case is noteworthy as indolent course in primary cutaneous mucormycosis with vascular involvement is rather rare. Even with a negative culture, R. Variabilis is a candidateetiologic agent as it usually presents a chronic evolution. Histopathologically, most panniculitis related to fungal infection are reportedas pancreatic panniculitis mimickers. In our case, only scarce ghost adipocytes were found and the main histopathological findings were a lobular panniculitis with vasculitis and an extensive basophilic necrosis. Thus, these histopathologic findings should raise suspicion of infection related-panniculitis, and PAS and Grocott stainings should be performed to rule out fungi.