Extramammary myofibroblastoma in the head and neck region.

Background: Mammary myofibroblastoma is a benign mesenchymal tumor of the breast. Extramammary location is very rare and usually occurs along the embryonic milk-line.

Methods And Results: In this article, we present a case of a woman with an infra-auricular swelling. A diagnosis could not be made on CT scans, so the mass was surgically removed. Histological examination showed spindle cells in clusters, with CD34, desmin, and actin expression. The diagnosis of extramammary myofibroblastoma was made.

Conclusion: We describe this case because of the unusual location of this rare tumor. Furthermore, we want to highlight the possible relationship between (extra)mammary myofibroblastoma and spindle cell lipoma (SCL). SCL has a predilection site in the posterior neck. Both tumors show the same clinical behavior, a close histological resemblance, and their cells are both immunoreactive for CD34 and CD10. The loss of RB/13q14 and FKHR/13q14 loci, which is typically found in SCL cells, was also shown in this case.