Primary mycetoma of the calcaneum: Case report on an unusual hazard of barefoot walking

Abstract

Introduction: Mycetoma is a rare tropical fungal infection characterized by a clinical triad of subcutaneous swelling, multiple discharging sinuses, and a purulent discharge containing granules. If left untreated, the disease can progress from cutaneous to intraosseous and can cause osteomyelitis. In very rare instances labeled "primary mycetoma", the fungus is insidiously inoculated directly into the bone and causes osteomyelitis without any preceding cutaneous involvement. This can make the diagnosis very difficult.

Presentation of case: A twelve-year-old girl with a history of walking barefoot, presented with pain and inability to bear weight on her left foot. There was no overlying cutaneous involvement. X-ray showed an osteolytic lesion in the calcaneum. After the failure of antibiotic treatment, the diseased bone was excised. Black granules were discovered inside the lesion and their histopathology confirmed a diagnosis of primary eumycetoma. After some time, the disease relapsed, necessitating another debridement. This occurred many times with worsened severity in each successive episode. Because of worsening disease and failure of both antifungal and surgical treatment, foot amputation was done.

Discussion: Primary mycetoma is an insidious fungal infection that causes osteomyelitis without any cutaneous findings. Timely diagnosis and treatment provide the best chance of preventing an amputation.

Conclusion: A high index of suspicion must be maintained for patients presenting with symptoms of osteomyelitis without any skin involvement so that timely diagnosis and treatment can prevent the progression of the disease and the need for amputation.

Keywords: Barefoot walking; Calcaneum; Chronic heel pain; Osteomyelitis; Primary mycetoma.