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mammary-type myofibroblastoma

Friday 31 March 2017

Mammary-type myofibroblastoma (MTMF)

Definition: Mammary-type myofibroblastoma (MTMF) is a benign mesenchymal neoplasm initially described to occur in the breast. MTMF is typically CD34 and desmin positive and genetically has rearrangement or deletion of 13q14, resulting in loss of Rb expression by immunohistochemistry (IHC).


- Mammary-type myofibroblastoma

MTMF appears more common at extramammary sites than in the breast and can cause diagnostic difficulty when atypia or epithelioid morphology is present or when located in an unusual anatomic location.

MTMF is frequently positive for CD34 and desmin by IHC; however, rare cases are negative for both.

There is no evidence of any significant recurrence risk for MTMF, even in the presence of positive resection margins.

The degree of morphologic overlap between spindle cell lipoma, cellular angiofibroma, and MTMF, in combination with shared genetics and slightly overlapping anatomic distribution, raises the question of whether or not these tumors are truly distinct entities or instead represent points along a single spectrum of genetically related tumors.


- mammary epithelioid myofibroblastoma
- leiomyomatous variant of myofibroblastoma

See also

- mammary tumors
- mammary myofibroblastoma