Benign mesenchymoma of the mediastinum: a case report.

Benign mesenchymoma is an uncommon tumor containing at least two or more differentiated mesenchymal elements in addition to fibrous tissue. The case we presented here is a 60-year-old male who suffered from a superior posterior mediastinal mesenchymal tumor composed predominantly of mature adipose tissue separated by fascicular bundles of spindle cells admixed with cartilage and osseous tissue. The spindle cells were confirmed to be smooth muscle in nature by trichrome Masson stain and immunohistochemical studies, providing a picture consistent with that of benign mesenchymoma. Complete removal of this neoplasm proved possible, and no sign of recurrence or distant metastasis was present to date. This rare case of benign mesenchymoma in the mediastinum is described, and the literature is reviewed.