Abstract

The necrotic eschar in an immunocompromised patient can signal an emergency for the dermatologist. An acutely ill 34 year old male presented for emergency care with fever in the setting of pancytopenia and chronic myeloid leukemia (CML) complicated by B-cell acute lymphoblastic leukemia (ALL). Treatment included broad spectrum antibiotics and eventually an acute chemotherapy regimen. 10 days after bone marrow biopsy, the patient developed low back pain with a 3.3cm erythematous indurated plaque with 1.4cm x 0.9cm dusky gray necrotic appearing center on the lower back. Initial biopsy noted leukemia cutis with a dermal infiltrate composed of large lymphoid cells with loose fine chromatin with prominent nucleoli and scant cytoplasm. Lesional cells were positive for immunohistochemical markers CD79a, Pax-5 and TDT and negative for CD3 consistent with the patient's known lymphoproliferation. GMS was negative for fungus. Soon, the biopsy sent for tissue culture started growing an unspeciated mold prompting repeat biopsies of the eschar and wound edge. Examination revealed subcutaneous tissue with hemorrhage and numerous non-septate fungal hyphae. Tissue culture confirmed Rhizopus species. Patient underwent multiple wound debridement procedures with mapping biopsies and was treated with appropriate antifungals. Leukemic infiltrates in the skin and other tissues in the body during both normal progression of CML and ALL are well known phenomena. In this critically ill patient there was high suspicion for an opportunistic fungal or bacterial process. However, initial biopsy demonstrated a diagnosis that while present was not the primary diagnosis of concern. It became clear the clinicopathological data did not correlate with the lesion in question. Close discussion with the dermatopathologist and clinical staff prompted urgent repeat biopsy with confirmation followed by treatment of the diagnosis.

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