Subcutaneous extraskeletal osteosarcoma of foot: A case report

Subcutaneous extraskeletal osteosarcoma (ESO) is a rare high grade malignant mesenchymal neoplasm consistent of approximately 1% of soft tissue sarcoma. Less than 10% of ESOs are superficial, originating in subcutis.

We reported a 72 years old male with chief complain of a painless slowly growing soft tissue mass in his plantar aspect of right foot in the last 9 months before admission. The plain radiography showed a large subcutaneous soft tissue mass in plantar area and heel, Magnetic resonance images displayed an irregular subcutaneous soft tissue mass extending from posterior lower leg to ankle and involving calcaneus inferiorly. A percutaneous core biopsy of the mass, obtained. The histopathology examination confirmed an soft tissue osteosarcoma. Subsequent wide local excision of the mass performed. Final histopathological result was subcutaneous extraskeletal osteosarcoma.

The patient has had no evidence of recurrence or/and distant metastasis at 25 months followed up. However, excising subcutaneous ESOs with a safe surgical margin is paramount for achieving the best outcome.

A subcutaneous ESO is a rare malignant tumor. We recommended that along with clinicohistological findings, radiological correlation is necessary for ruling out other diagnoses.