Subcutaneous basidiobolomycosis, a rare fungal infection typically affecting immunocompetent individuals in tropical regions, often mimics soft-tissue tumors or tuberculosis, leading to frequent misdiagnosis and unnecessary surgery, according to a recent clinical case study. Researchers documented the case of a 53-year-old man in India who presented with painless, indurated plaques on his thigh and groin, ultimately achieving complete resolution using oral suprabioavailable itraconazole without surgical intervention.
Understanding Subcutaneous Zygomycosis and Basidiobolus ranarum
Zygomycosis encompasses fungal infections caused by organisms from the class Zygomycetes, divided into Mucorales and Entomophthorales, according to clinical literature cited in the case report. While Mucorales typically cause rapid, aggressive tissue necrosis in immunocompromised patients, Entomophthorales—specifically Basidiobolus ranarum—produce chronic, localized subcutaneous disease in healthy hosts. The infection is endemic in tropical and subtropical regions across India, Africa, and Southeast Asia. According to the study authors, patients generally contract the fungus through minor trauma, insect bites, or spore implantation from contaminated soil or vegetation.
Diagnostic Challenges: Mimicking Malignancy and Tuberculosis
Diagnosing subcutaneous basidiobolomycosis remains notoriously difficult due to its indolent presentation. Patients usually develop firm, painless, indurated plaques that progress over weeks to months, closely resembling soft-tissue sarcomas, cutaneous tuberculosis, actinomycosis, sporotrichosis, or panniculitis. In this documented case, a 53-year-old tea vendor presented with three well-defined, non-tender plaques ranging from 3×4 cm to 6×8 cm over his right thigh and groin, accompanied by superficial ulceration on the largest lesion. Because these tumor-like presentations are common in regions where tuberculosis is prevalent, patients frequently undergo unnecessary surgical procedures or prolonged empirical therapies before receiving an accurate diagnosis, according to the report.
Histopathology and the Splendore-Hoeppli Phenomenon
Histopathological examination of a wedge biopsy from the patient revealed hyperkeratotic squamous epithelium alongside dense eosinophil-rich granulomatous inflammation. Pathologists observed broad, thin-walled fungal elements encased within an eosinophilic matrix—a hallmark feature known as the Splendore-Hoeppli phenomenon. Special stains like periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) further highlighted the aseptate hyphae, while fungal culture on Sabouraud dextrose agar confirmed the presence of Basidiobolus ranarum.
Non-Invasive Treatment With Itraconazole
In this case, the patient received suprabioavailable itraconazole at a dose of 65 mg twice daily. This specific formulation provides more predictable absorption and reduces dependence on gastric acidity compared to conventional capsules. Marked clinical regression was observed after just one month of therapy, and complete resolution occurred by five months, leaving minimal residual hyperpigmentation and minor scarring. A six-month follow-up confirmed no recurrence, successfully avoiding disfiguring surgery.
Did You Know?
Frequently Asked Questions
What is subcutaneous basidiobolomycosis?
It is a rare, chronic fungal infection caused by Basidiobolus ranarum that primarily affects the subcutaneous tissues of immunocompetent individuals in tropical and subtropical regions.
How do humans contract the infection?
Infection typically occurs through minor trauma, insect bites, or the accidental implantation of fungal spores from contaminated soil, decaying organic matter, or vegetation.
Why is the disease frequently misdiagnosed?
Because the lesions present as slow-growing, painless, tumor-like swellings, they are often mistaken for soft-tissue sarcomas, cutaneous tuberculosis, or deep bacterial infections.
Is surgery required to treat subcutaneous zygomycosis?
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