A rare presentation of carcinosarcoma of the bone in a young female; response with gemcitabine and docetaxel.

Background: Sarcomatoid carcinoma, or carcinosarcoma, is a neoplasm that contains both sarcomatous and carcinomatous elements. It is an extremely rare cancer most often arising from visceral organs. Here we report the seventh documented de novo case of carcinosarcoma of the bone, in a young female who showed initial clinical improvement with gemcitabine and docetaxel.

Case presentation: A 36-year-old Caucasian female presented with diffuse musculoskeletal pain that had progressed from her shoulder to her back, arm, and knee over 6 months. Imaging revealed diffuse sclerotic lesions of bilateral humeral heads, iliac and ischial bones, and thoracic and lumbar spine. Histopathologic examination of biopsies from the T9 vertebra and left femur showed mainly sarcomatous spindle cells with focal osteoid production. Immunostaining showed the cells to be OSCAR cytokeratin, patchy positive for pankeratin, and negative for CK7, GATA3, S100, SOX10, CD99, EMA, AE1/AE3, and HMW keratin indicative of an epithelial origin. After thorough clinical correlation, sarcomatoid carcinoma of a visceral organ was excluded and the diagnosis of primary sarcomatoid carcinoma of the bone was ultimately favored. She received chemotherapy with gemcitabine and docetaxel, and showed improvement at 6 months but ultimately passed 1 year post diagnosis.

Conclusions: Primary carcinosarcoma of the bone is an extremely rare malignancy. Early diagnosis is crucial as localized disease may be curable with resection. As shown in this case, combination chemotherapy with gemcitabine and docetaxel is a potential option in patients with unresectable or metastatic disease.