Imaging features of mammary-type myofibroblastoma of soft tissue: a case series with literature review

Abstract

Mammary-type myofibroblastoma (MTM) is a rare, benign neoplasm that is histologically identical to myofibroblastoma of the breast, but occurring in an extramammary site. The masses have been reported in superficial and deep soft tissue sites and visceral locations with the inguinal area and lower extremities are the most common. Most previous reports of MTMs have concentrated on clinical and pathological findings, with very limited information regarding imaging characteristics. Here, we describe three cases of MTM diagnosed at our institution, with a focus on imaging findings. We compare our findings with previously reported cases. Although MTM is rare, radiologists should be aware of this benign diagnosis as imaging characteristics can mimic those of liposarcomas and atypical lipomatous tumor/well-differentiated liposarcoma. Unlike those tumor types, MTM virtually never recurs post-resection, even when there are positive margins. Biopsy is necessary for proper diagnosis and recommended as an initial step to avoid overly aggressive treatment.

Mammary‐type myofibroblastoma of the perineum: Typical or rare location?

“…The majority of patients in past reports were men, with most patients aged 41–80 4–10 . MTMF frequently contains a fatty component visible on CT and MRI, but our case contained little fat, leading to difficulty in pre‐operative differentiation from other hypervascularized tumors such as paraganglioma or angiofibroma 6,11 . There is only one report of recurrence following incomplete resection, no reports of recurrence after complete resection, and no reports of post‐operative morbidity 9 …”

“…[4][5][6][7][8][9][10] MTMF frequently contains a fatty component visible on CT and MRI, but our case contained little fat, leading to difficulty in pre-operative differentiation from other hypervascularized tumors such as paraganglioma or angiofibroma. 6,11 There is only one report of recurrence following incomplete resection, no reports of recurrence after complete resection, and no reports of post-operative morbidity. 9 Pathological diagnosis is accomplished chiefly morphological findings, that is, bland, uniform spindle cells in short fascicles mixed with bands of thick hyalinized collagen and varying amounts of fat.…”

Extramammary myofibroblastoma of the oral cavity

“…Though extramammary myofibroblastoma was previously thought to arise from remnant breast tissue along the milk line, this theory has fallen out of favor given its tendency to occur throughout the body. The cell of origin has been proposed to be a subset of perivascular CD34+ mesenchymal stem cells 21 …”

Myofibroblastom einer männlichen Brust – Fallbericht und Literatur-Review

“…Extramammäre Lokalisationen sind ebenfalls häufig (dann als sog. "mammary-type myofibroblastoma", MTM definiert) [4,5]. Die Bezeichnung als Myofibroblasten geht auf fibroblastische Zellverbände zurück, die eine glattmuskuläre Differenzierung aufweisen.…”