Mammary-type Myofibroblastoma - a relative of spindle cell lipoma! (Yale case 3) pathology dermpath

This is an excerpt from my virtual slide session for the Yale pathology residents on 3.4.2021. Full video of the entire session is available for free here: kikoxp.com/pos.... WSI Digital slide for this case: kikoxp.com/pos....
A complete organized library of all my videos, digital slides, pics, & sample pathology reports is available here: kikoxp.com/pos... (dermpath) & kikoxp.com/pos... (bone/soft tissue sarcoma pathology).
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This video is geared towards medical students, pathology or dermatology residents, or practicing pathologists or dermatologists. Of course, this video is for educational purposes only and is not formal medical advice or consultation.
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[@JMGardnerMD]

This is an excerpt from my virtual slide session for the Yale pathology residents on 3.4.2021. Full video of the entire session is available for free here: kikoxp.com/posts/4739. WSI Digital slide for this case: kikoxp.com/posts/4600.

[@shuchitasharma5151]

These short videos are extremely helpful. Tough topics made really easy.

[@RaulRodriguez-sh6vb]

So helpful your videos encompass entities that can arise from many areas so we learn beyond ST bone and Derm

[@rutvijkhedkar]

Could you elaborate more on which entities you would include into this "RB1 family"?

[@JMGardnerMD]

Spindle cell/ pleomorphic lipoma. Atypical spindle cell/pleomorphic lipomatous tumor (which I believe are closely related to spindle cell/pleomorphic lipoma). Mammary type myofibroblastoma. Cellular angiofibroma of genitals. Superficial acral fibromyxoma. Pleomorphic fibroma of skin.

[@aakrutishah-5635]

I dint understand desmin positivity… could you explain it again? Can Myofibroblasts be desmin positive?? And also the last thing ..dilated blood vessels it shows… so how to differentiate it from SFT??

[@JMGardnerMD]

This entity is usually desmin positive. Other types of myofibroblasts can also be desmin positive sometimes. Myofibroblastoma can look very similar to SFT and both are cd34 positive. The difference is myofibroblastoma usually has more palisading, is desmin positive, and has loss of RB1 expression. SFT will be positive for STAT6.