Mycobacterial pseudotumor of the plantar fascia: how common is it?

Mycobacterial spindle cell pseudotumor (MSCP) is an extremely rare complication of mycobacterial infections. It has been reported to occur in various sites such as skin, lymph nodes, bone marrow, lungs, and spleen. This tumor-like lesion can be confused clinically as well as radiographically with dermatofibroma, nodular fasciitis, xanthogranuloma, and Kaposi's sarcoma. While this lesion is rare and has been previously reported to occur only in superficial skin, we emphasize its consideration and inclusion in the differential diagnoses when a deep soft tissue mass is complicated by symptoms of deep tissue infection secondary to abscess formation in immunocompromised hosts. Here, we present the clinical and radiologic findings of a case of MSCP involving the deep plantar sheaths.