mammary-type myofibroblastoma
Mammary-type myofibroblastoma, although first described in the breast, is now recognized to occur at a wider variety of extramammary locations, most often the inguinal region.
It shares cytogenetic similarities with spindle cell lipoma, to which it is probably closely related.
References
The evolving classification of soft tissue tumours: an update based on the new WHO classification. Fletcher CD. Histopathology. 2006 Jan;48(1):3-12. PMID: #16359532#