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Case Reports

Abstract

We present the case of an 87-year-old female with acute myeloid leukemia (AML) presenting with a painful, non-healing leg wound at the site of a previous invasive squamous cell carcinoma. Six months prior, the patient had undergone Mohs micrographic surgery.  Physical examination revealed a 14-cm x 10-cm, irregularly shaped necrotic ulcer with rolled, violaceous borders. Punch biopsies were performed with concern for pyoderma gangrenosum. Biopsy from the violaceous border revealed diffuse sheets of medium-sized to large, immature mononuclear cells with abundant eosinophilic cytoplasm, large nuclei and dispersed chromatin, with atypical mitotic figures. Immunohistochemical studies demonstrated diffuse expression of CD4, CD33, lysozyme and myeloperoxidase; the neoplastic cells were negative for CD3, CD43, CD34, CD56, CD117, CD123, and CD138. The histopathologic and immunophenotypic findings were diagnostic of AML-leukemia cutis. Biopsy from the central eschar revealed diffuse dermal necrosis with bacterial colonies and fungal hyphae and yeast highlighted by Gram and periodic acid-Schiff (PAS) staining respectively. Tissue cultures from the wound grew Candida albicans, Candida parapsilosis, Actinomyces odontolyticus, and Klebsiella pneumonia. Leukemia cutis (LC) results from the skin infiltration of malignant leukocytes. Polymicrobial infections in immunosuppressed patients with cancer are relatively rare and likely underreported. There have only been two previously reported cases of LC lesions superinfected with fungal pathogens, and only one case with both fungal and bacterial superinfections. We present this case to highlight a rare presentation of LC and polymicrobial infection masquerading as pyoderma gangrenosum, and the critical role of biopsy in identifying rare pathologies that would alter subsequent treatment.