Osteosarcoma Beyond the Long Bones: A Rare Case in the Index Finger

Case Report

Abstract

Osteosarcoma is the most common primary malignant bone tumor, typically arising in the metaphyseal regions of long bones. Involvement of the bones of the hand is exceedingly rare, accounting for less than 1% of cases, often leading to delayed diagnosis and treatment.
We report a rare case of high-grade osteosarcoma in the distal phalanx of the right index finger in a 78-year-old male. The patient presented with a five-month history of painless swelling, initially suspected to be benign. Radiographs revealed a lytic, destructive lesion, and an excisional biopsy confirmed high-grade osteosarcoma with malignant osteoid. Complete resection was achieved with negative soft tissue margins. After multidisciplinary review, adjuvant chemotherapy was withheld due to the patient’s age, tumor localization, and clean margins.
This case highlights the importance of considering osteosarcoma in the differential diagnosis of atypical finger masses, especially in elderly patients, to enable timely and effective treatment.