Multicentric osteosarcoma presenting as retrobulbar mass: A diagnostic enigma

Abstract

Osteosarcoma is the most common primary malignant bone tumor of children and adolescents. It often presents as a solitary lesion; multicentric osteosarcoma with synchronous lesions occurring at multiple skeletal sites is very rare. We report a 9-year-old boy with multicentric osteosarcoma who presented with a left retrobulbar non-sclerotic mass. The multiple lesions in bone were mostly non-sclerotic on radiological examination except for a single lesion in the left tibia. Biopsy of the retrobulbar mass showed an unclassifiable poorly differentiated malignant tumor. Marrow aspiration smears showed many large, often segregated, round cells that expressed NB84a. However, trephine biopsy showed the formation of tumoral osteoid by the malignant cells, finally permitting the definitive diagnosis of osteosarcoma to be made. A hypertetraploid clone with complex structural abnormalities was demonstrated by cytogenetic study.

Synchronous multicentric osteosarcoma involving mandible and maxillas

“…Second, bone metastasis is not rare in ordinary osteosarcoma. Third, bone metatasis via venous channels cannot be excluded 2,9,10 . Bone-to-bone metastases could occur via a similar mechanism as in prostate cancer via Batson's venous plexus, or intraosseous embolization through marrow sinusoids.…”

“…SMO occurs earlier than ordinary head and neck osteosarcoma, which occurs most commonly in the third and fourth decades 5 . Whether this tumor represents a true multifocal primary osteosarcoma or an aggressive metastatic spread of a unifocal osteosarcoma remains under debate [8][9][10] .…”