Case Number : Case 2871 - 08 July 2021 Posted By: Saleem Taibjee

No high grade atypia. One dermal mitosis, typical.  No expansive mass-forming intradermal growth. Not important pagetoid epidermal spreading. Kamino’s bodies. My spot is Spitz nevus, angiomatoid type. 

Traumatized Spitz nevus.

Agree. Traumatized Spitz Nevus. 

Spitz nevus 

Yes, well done. I also favoured traumatised, but benign, Spitz naevus. There were nice Kamino bodies. But these are difficult cases, and to illustrate this, when I did share this case with an experienced pathologist he had favoured melanoma (but I disagreed). After hearing his opinion I thought it would be worthwhile pursuing the case with some immunohistochemistry. In particular, BRAFV600E was negative, but interestingly NTRK positive (see below). The latter suggests that this is a Spitz underpinned by a NTRK fusion pathway, but of course this does not in itself indicate a benign diagnosis because NTRK has been reported in the whole spectrum of Spitz tumours. Even so, an immuno panel of BRAFV600E and ALK / NTRK / ROS-1 can sometimes be helpful in distinguishing 'spitzoid' superficial spreading melanoma from a true Spitz lineage, as in this case.

BW
Saleem

beautiful stains. I love the NTRK stain. thanks for sharing.