A pictorial review of rare soft-tissue tumors and tumor mimics around the foot and ankle: Magnetic resonance imaging done but need the gun

Lumps around the ankle and foot are commonly encountered in clinical practice and pathologies arise from the tendons, ligaments, plantar fascia, synovium, retinaculum, vessels, nerves and bones. Majority of these are benign and malignant conditions are relatively rare. Diagnosis is often delayed as the presentation is nonspecific in the form of pain, swelling, and restricted motion. This can lead to increase in morbidity especially in aggressive lesions. Hence, the radiologist needs to be abreast with the imaging features and differential diagnosis of these soft-tissue masses around the ankle and foot. Radiographs and ultrasound are usually the first imaging performed. However, magnetic resonance imaging (MRI) is the imaging modality of choice for the assessment of soft-tissue lesions and imaging features of majority of the entities is relatively characteristic. Diagnosis in majority of the conditions can be made on MRI alone and histopathology is warranted for definitive diagnosis in only a few rare cases. In this pictorial review, we describe imaging features of some rare soft-tissue lesions around the ankle and foot encountered in our practice that could not be diagnosed on imaging alone and needed guided biopsy. We also present points of differentiation between the lesions and their imaging differentials.