Case Number : Case 1822 - 23 May - Dr Uma Sundram Posted By: Guest

A tidy case from Dr Uma Sundram.

Geoff Cross - DermpathPRO Projects

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There seems to be two independent melanocytic neoplasms. The junctional one is for me a melanoma in situ with irregular nests with prominent confluent growth and adnexal compromise. On the other hand, the dermal component looks more like a dermal melanocytic nevus as we do not see mitotic figures and there seems to be some maturation in pic 4 and 6. 

Hmm, looks like superficial dermal scar to me.  My guess is compound congenital nevus with recurrent/traumatized nevus phenomenon.  Can't really tell if the junctional component goes far past the dermal component at the edges in these photos though.

Looks like a recurrent/traumatized phenomenon...agree with sfwenson.

I think there is a zonal disposition in this lesion that represents a recurrent nevus. There is also an activation of the lentiginous/juncional melanocytes.

Recurrent nevus (pseudomelanoma) to me more than melanoma? Would HMB45 help?

I think it is all benign. Agree with possible recurrent nevus (pseudomelanoma). I don't see epidermal upward scatter. No dermal mitoses. I would like to see better how the epidermal component behaves laterally beyond the "scar". A melan A would help to see easier symmetry and demarcation  . 

Agree with recurrent/persistent nevus. There is an architecturally disordered junctional melanocytic proliferation restricted to the underlying band area of dermal scar, with residual banal intradermal nevus at the bottom and on the sides.

I think reviewing the glass slide of the initial shaving biopsy is the best way to rule out melanoma. HMB-45 is useful when the initial biopsy is not available, with the caveat that recurrent/persistent nevus can lack obvious immunohistochemical maturation with this immunomarker, a pitfall that could be misconstrued as evidence of melanoma.

Yeah probably you guys are right, have to be very cautious with this kind of dx without CPC though

Recurrent naevus/pseudomelanoma overlying a dermal scar. A banal intradermal naevus is present beneath the scar.

I'd like to see the borders. nested>>single. Only a few melanocytes above DEJ. Some pulverocytes.  traumatized nevus > melanoma on nevus 

Recurrent nevus.  The lesion was laterally transected but we favored nevus over melanoma for all the reasons suggested. The lesion was re-excised.