Osteosarcoma with rhabdomyosarcomatous component or so-called malignant mesenchymoma of bone

Abstract

Background: Primary malignant mesenchymoma of the bone is a rare neoplasm consisting of two or more unrelated malignant mesenchymal components. The literature reports fewer than 20 cases, most of which were composed of osteosarcoma and liposarcoma.

Observation: We report an exceedingly rare case of primary malignant mesenchymoma of bone composed of rhabdomyosarcoma, osteosarcoma, and a minor chondrosarcoma component, arising in the right proximal humerus of a 15-year-old girl. The rhabdomyosarcomatous component was present in the initial biopsy and persisted in surgical specimen following chemotherapy.

Conclusion: Effect of chemotherapy is enigmatic since rhabdomyosarcomatous component could appear, persist or disappear after chemotherapy according to literature.