An Unusual Presentation of Keratinous Cyst - A Case Report.

Introduction: Keratinous cysts are benign lesions that primarily affect the skin but can occasionally involve bones, presenting a diagnostic challenge due to their rarity and varied manifestations.

Case report: We present a case of a 65-year-old male farmer who presented with swelling and persistent pain in the right foot, particularly over the third toe. The patient had a history of trivial trauma and previous incision and drainage for a foot swelling. Radiographic and magnetic resonance imaging findings indicated a well-defined lytic lesion with cortical thinning and breach over the third metatarsal, raising suspicion for tuberculous osteomyelitis. Surgical exploration revealed an encapsulated cyst filled with cheesy material. No sequestrated bone or osteomyelitis was found.

Conclusion: The cyst was excised, and the affected bone underwent curettage. Histopathological examination confirmed the diagnosis of a keratinous cyst with no evidence of granuloma or malignancy. Postoperatively, the patient experienced an uneventful recovery, undergoing immobilization and later non-weight-bearing mobilization. This case highlights the importance of considering non-infective causes, such as keratinous cysts, when evaluating bone lesions with lytic characteristics, especially in the presence of a history of trauma or previous interventions. Prompt surgical intervention and histopathological examination are critical for accurate diagnosis and management.