Case Number : Case 2881 - 22 July 2021 Posted By: Saleem Taibjee

Combined Nevus ( DPN + Common Nevus ). Useful Beta-catenin. 

Combined nevus (common and dermal  Spitz nevus).

BAP-1?

Angiomatoid Spitz Nevus

Spit’z Nevus is usually a Kinase-mutated lesion ( like HRAS, ALK etc ), and this genetic pathway should be mutually exclusive with BRAF mutation of the common nevus. Beta catenin of DPN fits best with BRAF.  But this is only a my speculation. I was thinking of a mixed Common+ DPN because of the morphology. 

Here is the BRAF V600E immunostain (negative) below:

Well done, Vincenzo.

Yes, this is a combined naevus. The beta-catenin is shown below. This demonstrates nuclear staining within the more epithelioid component (1st image), in contrast to cytoplasmic only in the more conventional naevocellular component (2nd image). I was somewhat perplexed by the negative BRAFV600E as above. But I am grateful for the review by Arnaud de la Fouchardiere who confirmed my impression of combined naevus with deep penetrating naevus-like clone, and Arnaud also indicates that most, BUT NOT ALL, such lesions have a BRAF background. The Ki67 is reassuringly low throughout, and p16 preserved.

BW, Saleem

thanks for wonderful case sir, based on morphology we must not diagnose it as melanoma

beautiful case!

On 27/07/2021 at 08:49, Saleem Taibjee said:

Well done, Vincenzo.

Yes, this is a combined naevus. The beta-catenin is shown below. This demonstrates nuclear staining within the more epithelioid component (1st image), in contrast to cytoplasmic only in the more conventional naevocellular component (2nd image). I was somewhat perplexed by the negative BRAFV600E as above. But I am grateful for the review by Arnaud de la Fouchardiere who confirmed my impression of combined naevus with deep penetrating naevus-like clone, and Arnaud also indicates that most, BUT NOT ALL, such lesions have a BRAF background. The Ki67 is reassuringly low throughout, and p16 preserved.

BW, Saleem

The BRAF negative also puzzles me. what review by  Arnaud de la Fouchardiere are you referring to? Thanks Saleem,

Arnaud directly reviewed this case (I'm not referring to a review article).