Mammary myofibroblastoma

Mammary myofibroblastoma, also myofibroblastoma of the breast, is a rare benign pathology of the breast.

Mammary myofibroblastoma
Diagnosis in short
Mammary myofibroblastoma. H&E stain.
Synonyms	myofibroblastoma of the breast, breast myofibroblastoma
LM	well-circumscribed lesion, wpindle cells without nuclear atypia arranged in fascicles, interspersed thick bundles of collagen.
LM DDx	metaplastic breast carcinoma, fibromatosis, leiomyoma of the breast, nodular fasciitis, phyllodes tumour, spindle cell lipoma
IHC	CD34 +ve, SMA +ve, desmin, +ve, vimentin +ve, S-100 -ve, beta-catenin -ve
Site	breast
Clinical history	postmenopausal female or older male
Prevalence	rare
Prognosis	benign
Treatment	excision

General

• Rare.
• Excision = cure.
• Postmenopausal females and older males.

Note:

• In extra-mammary sites the tumour is known as a mammary-type myofibroblastoma may immunohistochemically and histomorphologically overlap with spindle cell lipoma.

Microscopic

Features:

• Well-circumscribed lesion.
• Spindle cells without nuclear atypia arranged in fascicles.
• Interspersed thick bundles of collagen.

Notes:

• No calcifications.
• No necrosis.
• No hemorrhage.

DDx:

• Metaplastic breast carcinoma.
• Fibromatosis.
• Leiomyoma of the breast.
• Nodular fasciitis.
• Phyllodes tumour.
• Spindle cell lipoma.

Images

• 

  Mammary myofibroblastoma - low mag. (WC/Nephron)

• 

  Mammary myofibroblastoma - intermed. mag. (WC/Nephron)

• 

  Mammary myofibroblastoma - high mag. (WC/Nephron)

www:

• Mammary myofibroblastoma - several images (upmc.edu).

IHC

Features:

• CD34 +ve.
• Desmin +ve.
• Actin +ve.
• Vimentin +ve.
• SMA +ve.

Others:

• S-100 -ve.
• Beta-catenin -ve.^{[citation needed]}
• H-caldesmon -ve.^{[citation needed]}
• CK7 -ve.
• HMCK -ve.

See also

• Breast pathology.