This 47-year-old man developed a necrotic ulcer with eschar and purpuric borders following immunosuppression for an orthotopic liver transplant (HCV). The lesion was biopsied and sent for both histology and cultures. The clinical differential diagnosis included deep fungal infection and ecthyma gangrenosum. The histopathology showed scattered filamentous fungi within the areas of necrosis. The apparent aseptate and ribbon-like nature of the fungus is highly suggestive of zygomycosis (mucor, rhizopus, etc), however, degenerated Aspergillus species can look like this, and thus cultures are necessary for confirmation.
Histologic sections of skin show a mixed inflammatory infiltrate involving the full-thickness dermis, with relatively spared epidermis in this field. There looks to be a deep abscess an well as necrotic vessels.