Pathology: secondary osteosarcoma

Osteosarcoma, radiation-associated

In field of prior radiotherapy for nasopharyngeal carcinoma

  • Lobulated; spindle-epithelioid cell fascicles

  • Eosinophilic cytoplasm

  • Ovoid nuclei with prominent nucleoli and moderate-marked pleomorphism; conspicuous mitotic activity

  • Broad areas of osteoid with focal mineralization

Osteosarcoma, radiation-associated

In field of prior radiotherapy

  • Spindle-epithelioid cells with fascicular-herringbone pattern

  • Amphophilic cytoplasm

  • Round-ovoid nuclei with mild-moderate pleomorphism; conspicuous activity

  • Delicate seams of osteoid lacking mineralization; patchy necrosis

Osteosarcoma, radiation-associated

In field of prior radiotherapy

  • Spindle-epithelioid cells with patternless distribution

  • Pale amphophilic cytoplasm

  • Round-ovoid nuclei with mild-moderate pleomorphism; occasional activity

  • Broad bands of osteoid with focal mineralization

  • IHC: SATB2

Osteosarcoma, radiation-associated

In field of prior radiotherapy

  • Spindle-epithelioid cells with vague fascicular pattern

  • Pale amphophilic cytoplasm

  • Round-ovoid nuclei with moderate-marked pleomorphism; conspicuous activity

  • Broad bands of osteoid with focal mineralization