Resident Rounds: Part III – Primary Cutaneous Mucormycosis

10% to 19% of mucormycosis cases, and has the best clinical outcome with a mortality rate of 15%.²

Mucorales species are ubiquitous in nature, found in soil and moldy foods, and contracted via inhalation of spores or direct inoculation.^1,3,6,7 Cutaneous mucormycosis may be contracted through a variety of skin wounds, including trauma, surgery, injection sites, arterial lines, insect bites, or even contaminated adhesive tapes or dressings.^2,5 Risk factors include diabetes, hematologic malignancies, allogeneic hematopoietic stem cell transplant, organ transplant, graft-versus-host disease, chronic corticosteroid use, chemotherapy or other immunosuppressive medications, deferoxamine therapy, hepatic or renal failure, intravenous drug use, and major trauma or burn wounds.^2-10

Cutaneous mucormycosis manifests in a variety of non-specific clinical presentations, including fever, erythema, edema, vesicles, or pustules that may evolve into a necrotic ulcer, cellulitis, or gangrene.^2,5,7,8 The infection may be acute and aggressive, resembling necrotizing fasciitis, or chronic over the course of years.² Prompt treatment is imperative, as the infection is angioinvasive and may eventually lead to arterial necrosis, thrombosis, tissue ischemia or infarction, and dissemination.^2,4,6 Therefore, untreated infections may result in limb amputation or death.⁹

The diagnosis of mucormycosis relies on histopathology and tissue culture, as blood cultures are typically negative.^1,2,4,6 Characteristic histopathologic findings include broad (5-25 mm), non-septate hyphae, branching at 90°.^1,3,7,9 The treatment rubric involves surgical debridement, antifungals, and control of underlying conditions, such as diabetes, neutropenia, or tapering/ cessation of immunosuppressant medications.^{2-4, 6-9} The preferred first line antifungal therapy is liposomal amphotericin B or amphotericin B lipid complex.^1,3-5,7,8 Second-line treatment options include posaconazole5 or a combination of amphotericin B and caspofungin.¹ Recombinant growth factors may also be used in the context of neutropenic patients.^1,4 Duration of antifungal treatment is currently not well defined, but is typically conducted for at least 6 to 8 weeks.¹

Primary cutaneous mucormycosis is an uncommon yet severe opportunistic infection, resulting in life-threatening angioinvasive necrotic wounds. Due to the high morbidity and mortality of this disease, prompt diagnosis, aggressive treatment, and reversal of predisposing conditions are imperative for limb salvage and survival.