Chondroblastoma of proximal tibia diagnosed by arthroscopy-guided biopsy: a case report

Chondroblastoma considered a rare form of osseous neoplasm contributes less than 1% of all bone tumours. It is typically found in young patients with chief complaints of moderate pain with joint stiffness. It develops as a lytic lesion in the epiphysis of long bones which might spread to the metaphysis. We report a case of an 18-year-old patient who presented with progressive right knee pain which aggravated with movements. Investigations included X-ray, magnetic resonance imaging (MRI), and biochemical assessment. A focal, well-defined, lesion in the upper end of the tibia with surrounding marrow oedema was observed and diagnostic arthroscopy was taken for management. Histopathology of specimen observed chondroblasts proliferation with areas of mature cartilage, and giant cells confirming intrasynovial chondroblastoma. Usually, surgery is the treatment of choice; however, possibilities of the secondary bone cyst, haemosiderin deposition on the joint, etc., make treatment approaches uncertain. Diagnostic arthroscopy is a rare but essential modality in such cases due to better visuals, complete tumour excision, and combination with adjuvant therapies. Chondroblastoma, if untreated, proves detrimental, hence, a thorough evaluation is critical for overall better outcomes.