Mammary-Type Myofibroblastoma



Mammary-Type Myofibroblastoma


Cyril Fisher, MD, DSc, FRCPath





Key Facts


Terminology



  • Benign spindle cell lesion of modified smooth muscle cells in fibrous and fatty stroma


Clinical Issues



  • Identical to mammary myofibroblastoma


  • Rare, mainly inguinal region


  • 4th-7th decades (mean age: 55), mostly in males


  • Simple excision is usually curative


Microscopic Pathology



  • Bland spindle cells


  • Rare focal atypia or epithelioid appearance


  • Mitoses up to 6 per 10 HPF


  • Adipose tissue component


  • Coexpression of desmin and CD34


Top Differential Diagnoses



  • Spindle cell lipoma


  • Solitary fibrous tumor






Hematoxylin & eosin shows a cellular spindle cell proliferation incorporating subcutaneous fat image.






Hematoxylin & eosin shows short uniform spindle cells arranged in fascicles and cords, infiltrating between collagen bundles.


TERMINOLOGY


Synonyms



  • Mammary myofibroblastoma


  • Extramammary myofibroblastoma


Definitions



  • Benign spindle cell lesion of modified smooth muscle cells in fibrous and fatty stroma


  • Originally described in breast


  • Also occurs in soft tissue locations including in “milkline”



    • Subcutis



      • Inguinal region most common


CLINICAL ISSUES


Epidemiology

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Mammary-Type Myofibroblastoma

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