Case Discussion
Myofibroblastoma is a benign lesion of stromal myofibroblasts, and is characterized by spindle-to-ovoid cells in haphazard fascicles, with intervening short collagen bundles. There is a wide morphologic spectrum. In this case, there is a prominent fatty component. The cells are also epithelioid in areas. The differential diagnosis includes spindle cell lipoma, fibromatosis, nodular fasciitis, leiomyoma, hamartoma, as well as carcinoma. A helpful immunopanel would include keratin, desmin, CD34, SMA, ER/PgR, beta-catenin.
