Conventional chondrosarcoma of the sternum presenting as a chest wall mass with multilobulated intra- and extra-thoracic extension.

Chondrosarcomas are rare malignant tumors, comprising 20% of all primary bone tumors. They are classified as primary or secondary based on their origin and as conventional or nonconventional based on histology. While conventional chondrosarcomas are the most common form, their occurrence in the chest, and more specifically in the sternocostal joints, is extremely infrequent. We present a case of a 61-year-old female with a longstanding history of a small stable-appearing anterior chest chondrosarcoma for well over a decade, which required surgical intervention after rapid and spontaneous growth. The unique growth pattern extending both extra-thoracically and intra-thoracically is a rare occurrence. Common radiological findings of chondrosarcomas that were appreciated in this case includes lytic lesions with matrix calcifications, endosteal scalloping, and soft tissue masses. Modern imaging techniques, like computed tomography (CT), are excellent for identifying and preoperative planning of chondrosarcomas, however, histology remains the gold standard for confirming the diagnosis.