Sarcomatoid carcinoma of the prostate: progression from adenocarcinoma is associated with p53 over-expression.

The pathogenesis of sarcomatoid metaplasia of prostatic adenocarcinoma is uncertain. The histologic features of sarcomatoid carcinoma arising in two patients with previously irradiated prostatic adenocarcinoma are reported and the relationship between prostatic adenocarcinoma and subsequent sarcomatoid carcinoma is investigated by immunohistochemical detection of epithelial and soft tissue tumor markers, and p53 protein.Two patients, aged 72 and 67 years, underwent localized radiotherapy for prostatic adenocarcinoma and re-presented with sarcomatoid carcinoma 41 months and 60 months later, respectively. In both cases the tumor consisted of anaplastic spindle cells with occasional osteoclast-like giant cells. The initial tumors showed immunohistochemical staining typical of prostatic adenocarcinoma with absence of expression of p53 protein. The subsequent sarcomatoid carcinomas were positive for vimentin and negative for epithelial cell markers. In both cases serial biopsies showed a temporal increase in tumor expression of p53 protein.The development of sarcomatoid carcinoma in prostatic adenocarcinoma is associated with progressive accumulation of p53. This is suggestive of increasing clonal dominance of dedifferentiated tumor cells carrying p53 mutations.