Proliferation of osteoclast-like giant cells in a metastatic bone tumor from stomach cancer: report of a case and analysis of the autopsy findings

Preoperative diagnosis of a giant cell tumor of soft tissue arising from the breast by ultrasound-guided core needle biopsy

Giant cell tumors of soft tissue (GCT-ST) arising in the breast are extremely rare. Herein, we report a case of a 45-year-old woman with a 5-cm mass in her left breast. Ultrasonography revealed a mainly well-circumscribed mass that contained a cystic lesion. Magnetic resonance imaging showed a fibrous capsule-covered mass that contained a high-intensity area, suggesting hemorrhaging. Ultrasound-guided core needle biopsy (CNB) revealed mononuclear histiocytic cells with a round shape or spindled appearance that was mixed with multinucleated giant cells. Immunohistochemical analysis revealed CD68-positive staining in the mononuclear and giant cells but negative staining for pancytokeratin. Preoperatively, the tumor was highly suspected of being GCT-ST. Histopathological results after a left mastectomy showed similar findings to CNB. The final diagnosis was GCT-ST in the breast. To the best of our knowledge, this is the first case report of a GCT-ST arising in the breast diagnosed by ultrasound-guided CNB.

Osteoclast-like giant cell tumor arising in the soft tissue of the breast: report of a case

Extraosseous manifestations of osteoclast-like giant cell tumors (OGCTs) in soft tissue are unusual, especially in the breast. However, multinucleated osteoclast-like giant cells have been described in association with epithelial malignancy, as a variant of breast carcinoma. We report a case of OGCT of the soft tissue of the breast, not associated with epithelial elements. To the best of our knowledge, this is only the second such case reported.