Extraskeletal Osteosarcoma of the Hand

Abstract

IntroductionExtraskeletal osteosarcoma (ESOS) is a rare tumour thatdoes not typically present in the hand. We describe a caseof ESOS, a rare soft tissue tumour, arising in the hand as arecurrent soft tissue lump. Establishing a histologicaldiagnosis can be difficult in this rare tumour. This casereport highlights the difficulty in the diagnosis andtreatment of this rare sarcoma.Case ReportA 56-year-old man presented with a swelling in his rightpalm that had increased in size for 3 months. He had fullfunction of his hand but complained of paraesthesia in hismiddle finger and radial half of his ring finger. There wasno history of injury or other comorbidity.On examination, there was a 3 cm, firm, non-tender,lobulated swelling in the centre of the right palm with noattachment to the skin or flexor tendons. His hand wasneurovascularly intact, with full range of movement, andthere was no axillary lymphadenopathy.Magnetic resonance imaging (MRI) showed a 3.9×2.9×2.5 cm mass in the superficial and deep compart-ments of the palm interposed between the flexortendons (Fig. 1). Ultrasound-guided needle core biopsyshowed no high-grade malignancy, but was non-diagnostic. He underwent function-preserving marginalexcision of the lesion. Histology showed a spindle celltumour of uncertain malignant potential with few mitoses,chondromyxoid areas and no osteoid (Fig.2), with clearexcision margins.Four months after excision, there was clinical and MRIevidence of local recurrence. Incisional biopsy showed ahighly cellular spindle cell neoplasm with a high mitoticindex, nuclear pleomorphism, areas of necrosis andosteochondroid foci. The diagnosis of high-grade ESOSwas confirmed by two musculoskeletal pathologists.No metastases were identified on computed tomography(CT) of the chest, abdomen and pelvis or radioisotope bonescan. He was commenced on doxorubicin and cisplatinchemotherapy. Clinical examination (Fig. 3)andMRI(Fig. 4) after completion of two cycles of chemotherapyshowed an increase in the size of the tumour. As the tumourwas non-responsive to chemotherapy and not amenable tolimb salvage, he underwent radical resection (below-elbowamputation). Resection histology confirmed ESOS withlittle necrosis. Following surgery, his chemotherapyregimen was changed to ifosfamide and etoposide.However, pulmonary metastases were detected onfollow-up chest imaging at 11 months, and he died ofadvanced metastatic disease.DiscussionESOS accounts for 1.2% of soft tissue sarcomas and 3.7–4.6% of osteosarcomas [2]. It is a tumour that arises in the