Case Number : Case 1518 - 19 April Posted By: Guest

Compound nevus, with some random atypical change in the dermal component, and some asymmetric intraepidermal placement of melanocytes...displastic nevus. There is  a maturation gradient in a intrapapillary dermal nest on the center of fig1, with type A melanocytes on the top and type B on the bottom.

Another not that easy thin melanic lesion. There is some assymmetry, expansile crowded nests, areas of confluence, impairment of clear maturation (demonstrated also with the homogeneous hmb-45 expression) and some cells with conspicuous nucleoli and hypercromasia. On the other hand the lesion starts and ends with nests, there is not a clear lentiginous growth, no pagetoid spread, absence of mitosis (even if I would make a ki67/phh3), extension to adnexae is not clearly seen (would do some levels) and the inflammatory infiltrate is scarce. I would go for MELTUMP in this particular case for further study with FISH/CGH but I would slightly favour a benign lesion. 

Agree with points made by Raul.

Overall, I think there are more reassuring features than concerning ones.The irregular pigment distribution (including a few ?dendritic ones) made me think of a combined naves/naevus with phenotypic heterogeniety.

My feeling is that this is a benign compound naevus. 

Largely nested, shallow melanocytic lesion. There is mild to moderate architectural atypia, and mild cytonuclear atypia. Difficult to assess maturation in this thin lesion, but some impairment as Raul has suggested is there. No active regression or overt atypia. p16 and PHH3 may not particularly help. If this is a completely excised lesion, I feel would represent a mildly dysplastic naevus.

Thin, junctionally "active", compound naevus with minimal atypia. Not overly worried on the H&E. Management based on clinical concern.

Agree with all of your assessments. We were not significantly worried about this lesion and ultimately called it a dysplastic nevus with mild atypia. Given the age of the patient, both patient and dermatologist opted for watchful waiting. It was interesting in seeing the range of approaches in this forum--these types of cases tend to be very instructional!