A 42-year-old male from a tropical rural region presented to a local clinic with a two-month history of reddish-brown, scaly patches on his inner thighs and groin area. The lesions were non-itchy but had progressively expanded, forming well-demarcated plaques with a wrinkled texture. He reported mild discomfort, particularly in hot and humid conditions.

His medical history was unremarkable, except for long-standing type 2 diabetes mellitus, which was poorly controlled due to limited access to medication. He worked as a farmer, spending long hours in warm, damp conditions. Physical examination revealed hyperpigmented, slightly macerated plaques in intertriginous areas without active inflammation or pustules. Wood’s lamp examination showed a characteristic coral-red fluorescence, raising suspicion of erythrasma.

A Gram stain of skin scrapings revealed Gram-positive rods, and a bacterial culture confirmed Corynebacterium minutissimum. The patient was advised on proper hygiene and prescribed oral erythromycin, along with topical fusidic acid. Follow-up after two weeks showed significant improvement, with fading lesions and no new spread. He was counseled on diabetes management and preventive measures to reduce recurrence.