Role of cytopathology in diagnosing phaeohyphomycosis masquerading as nerve abscess in a lepromatous leprosy patient: A case report

INTRODUCTION AND IMPORTANCE: Phaeohyphomycosis is a rare fungal infection primarily affecting immunocompromised individuals. Its clinical manifestations are diverse, and diagnosis can be challenging, particularly when lesions mimic other conditions. CASE PRESENTATION: A 66-year-old male, with a history of irregular leprosy treatment and prolonged steroid use, presented with symptoms suggestive of a nerve abscess. On examination, cystic swellings were observed on the left thumb and leg. Histopathological examination and fine needle aspiration cytology (FNAC) revealed melanized hyphae, leading to a final diagnosis of phaeohyphomycosis. The patient was treated with oral itraconazole, leading to regression in lesion size. CLINICAL DISCUSSION: Leprosy patients on long-term steroids are especially susceptible. The pathogenicity of these fungi in immunocompetent people is believed to be due to melanin in their cell walls, which defends against host defenses. Diagnosis involves histopathological examinations, staining, and fungal culture. Treatment involves surgical excision and antifungal drugs. If untreated, it can lead to severe complications including fatal brain infections. CONCLUSION: This case highlights the unusual presentation of phaeohyphomycosis mimicking a nerve abscess in a leprosy patient. It underscores the importance of a high degree of clinical suspicion in diagnosing such rare infections, particularly in immunocompromised individuals. It also emphasizes the value of FNAC in reaching a definitive diagnosis. Prompt diagnosis and appropriate treatment are essential to prevent potentially serious outcomes.