Basal Cell Carcinoma With Osteosarcomatous Component

Sarcomatoid carcinoma or carcinosarcomas of the skin are rare. Basal cell carcinoma (BCC) with osteosarcomatous differentiation is the second most common sarcomatoid carcinoma of the skin, following squamous cell carcinoma with heterologous mesenchymal differentiation. There are only 11 cases of BCC with osteosarcomatous component reported in the literature, with limited documented molecular analyses. The authors report the clinical and histological features of 2 cases with molecular analyses for recurrent mutations in 17 cancer genes. In both cases, the epithelial or BCC component was positive for BerEP4 and high-molecular weight cytokeratin, whereas the sarcomatous component was negative for both markers. Mutational analyses revealed TP53 mutation in 1 case with p53 expression noted in both components. The other case was negative for both p53 expression and TP53 mutation.