Case Number : Case 2857- 18 June 2021 Posted By: Dr. Richard Carr

spindle cell nevus of Reed

Seems like melanoma arising in a dysplastic nevus. One part is very epithelioid, while the other part shows small nevic cells.  

8 hours ago, Meenakshi Batrani said:

Seems like melanoma arising in a dysplastic nevus. One part is very epithelioid, while the other part shows small nevic cells.  

Yes. The left part should be a melanoma, because of a nodular-expansive intradermal growth. The spindle/epithelioid cells are very atypical. And p16 loss is in keeping with melanoma. Useful a Prame stain.

I think it is a (spitzoid?) melanoma. It is asymmetric with atypical cells and (localized) loss of p16. Can we attribute the fibrosis in pic 3 and 5 on dysplastic nevus, regression or location (back)?

I agree with a "Spitzoid" or Spitz-like melanoma arising in a dysplastic naevus. The clue in image 5 is the expansile nests that squeeze the elongated rete (umbrella sign = narrow compressed rete with thinned curving epidermis on each side) or also referred to as the puffy shirt sign (rounded expansile nests that bulge the epidermis). The null p16 is supportive of melanoma arising in a naevus and I believe is seen in around 70% of naevoid melanomas.