Secondary Chondrosarcoma of the Clavicle: A Case Report

Chondrosarcomas are uncommon cartilaginous tumours and are the third most common tumours arising from the bone. These tumours are low to high grade malignant chondroid tumours. Most of these lesions arise de novo and are considered primary chondrosarcomas. Tumours that develop from the cartilaginous cap of existing benign tumours like enchondroma or osteochondroma are known as secondary chondrosarcomas. Herein, the authors presented a case of a 41-year-old man who presented with a history of pain and swelling in his left clavicle for a duration of six months. Upon examination, clinicians felt a hard mass in the left clavicle region, prompting them to explore radiological insights. A radiograph revealed a lobulated sclerotic region overlying the medial aspect of the left clavicle. Computed Tomography (CT) further revealed an exophytic lesion arising from the clavicle. Magnetic Resonance Imaging (MRI) further characterised the lesion and raised suspicion of a complex malignant lesion of chondroid origin. Histopathological analysis confirmed it to be a chondrosarcoma of the clavicle. Subsequently, the patient underwent tumour excision with partial claviculectomy. Secondary chondrosarcomas are low to high grade malignant chondrogenic bone tumours that arise in pre-existing benign tumours. They may develop in osteochondromas, enchondromas, fibrous dysplasia, Paget's disease, irradiated bone, and synovial chondromatosis. Although sarcomatous transformation is common in osteochondromas, secondary chondrosarcomas of the clavicle are extremely rare.