Case Number : Case 1038 - 16th June Posted By: Guest

is it possible to be a minimal deviation melanoma? ki67 and HMB45 are needed

This is a somehow difficult lesion. Fairly circumscribed, yet asymmetrical. The lesion appear nicely maturing. However, I am worried about this expansile nodule that is sharply delineated from the rest of the nevus in the background. It reminded me of proliferation nodules in congenital nevi. From the history, I understood that the patient presents with darkening lesions of 6 months. Does this mean multiple lesions? Are the darkening lesions arising de novo or on top of another lesion in the background, ? Congenital nevus? and has been present for 6months? Cytologically, the cells of this nodule do not look like typical epithelioid melanoma cells, yet they show prominent nucleoli and are different than the background dermal nevocytic cells, but they show no mitotic activity. It does not fit in clonal or (inverted type A) nevus. There is an isolated typical mitosis in the background dermal component, I do not think it is worrisome because the patient is a child (13 years) and I think this is expected in such age.
What is worrying me is this dermal nodule!!!!!
If these are lesions developing within a giant congenital nevus, I will consider it proliferation nodules.
If they are arising de novo, then may be it is better to describe this lesion as MELTUMP and do further work including IHC and genetic studies?? Waiting to read expert opinions...

A late proliferative nodule arising within a congenital melanocytic nevus.

I don´t think this is a melanoma. I agree with Robledo, proliferative nodule arising in a congenital nevus.

Naevoid melanoma.

Clonal naevus

Agree with Dr. Richard Carr: clonal nevus.

Agree with Dr Abdul-Kadir: Nevoid melanoma.

Interesting case that highlights the value of genetic studies in problematic melanocytic lesions...

I think we will find all clonal naevi are separated from their background lesion by an additional mutation / translocation etc. Not sure this proves a fully capable malignant melanoma though. I suspect this lesion will be of low risk (all be it uncertain potential).