Resident Rounds: Part III – Primary Cutaneous Mucormycosis

A 36-year-old man treated as an inpatient at an outside hospital with acute myelogenous leukemia presented to the emergency department with a 2-week history of a rapidly growing eschar on his right forearm. The lesion started at the site of adhesive tape placement for an intravenous catheter. The catheter was used only for normal saline. Once the tape was removed, the patient noticed an enlarging “black spot”. The lesion was rapidly growing, slightly tender, and malodorous to the patient. He had tried no treatments.

Additional medical history included a spinal mass resulting in cord compression and leg weakness. His medications included only dexamethasone. The patient had declined all chemotherapeutic regimens in lieu of unspecified holistic treatments. Physical exam revealed a cachectic appearing male with a temperature of 100.8 degrees F and a tender 10 cm firm mass with overlying eschar on the right proximal forearm (Figure 1). Lab results revealed hemoglobin of 9 g/dL (13.8-17.2), platelets of 15,000/μL (150,000-450,000), and white blood cell count of 1.1 x 10³/μL (3.8 – 10.8 x 10³) with an absolute neutrophil count of 550 cells/μL. A comprehensive metabolic panel was within normal limits, including a glucose level of 105 mg/dL (<110). Punch biopsies were obtained from the border of the lesion for histopathologic analysis and culture.

Histopathologic examination of the punch biopsy revealed extensive necrotizing acute inflammation in the subcutaneous adipose tissue with broad non-septate hyphae branching at 90 degrees in the deep dermis consistent with mucormycosis (Figure 2). In addition, bacterial culture grew pseudomonas, bacteroides fragilis, staphylococcus epidermidis, and citrobacter.

Initially, the patient was treated with broad-spectrum antibiotics, including vancomycin, cefepime, and metronidazole. Once mucor was discovered via tissue biopsy, liposomal amphotericin B was started along with aggressive surgical debridements. The antibiotic regimen was narrowed to levofloxacin and metronidazole. After several debridements, no residual evidence of mucor species was clinically evident. Computed tomography (CT) scans of the head, chest, and abdomen were negative for additional abscesses. Compared to previous thoracic CT imaging, the spinal mass resolved completely. The dexamethasone was subsequently tapered to improve immune function. Repeat tissue cultures were negative. The patient was transitioned to IV posaconazole from amphotericin. When his medical condition was deemed stable, he was discharged to an acute rehabilitation unit for further medical care.

Mucormycosis, formerly known as zygomycosis, is a rare and aggressive opportunistic infection caused by saphrophytic fungi under the class Zygomycetes, order Mucorales, and genera Mucor, Rhizopus, Rhizomucor, and Lichtheimia.^1-8 This angioinvasive infection typically affects immunocompromised individuals and has a variety of manifestations including rhinocerebral (most common), pulmonary, cutaneous, gastrointestinal, and disseminated.^2,4-6,9 Primary cutaneous mucormycosis is the second most common form, accounting for