Case Number : Case 755 - 9th May Posted By: Guest

"Odd" naevus some spitzoid features. A deep mitotic figure. We can't really assess silhouette but the compact nature of the base (as oppoased to the individual cells infiltrating reticular dermal collagen in a classic Spitz) is a bit concerning. That said DPN may have mitotic figures and lack maturation with depth. I would not call out right on these images but would like to see the glass. Could do CGH as differential includes MELTUMP. My diagnosis odd Spitzoid / naevoid lesion of uncertain malignant potential but favour benign behaviour (with everything crossed!). I suspect there may be a US v's rest of the world divide.

I think it is melanoma, maybe a nevoid melanoma.

I do not feel comfortable also with this lesion. Junctional nests show some atypia and pleomorphism. Also dermal component shows some pleomorphism. The sheet like arrangement of the dermal component with no enough stroma inbetween and the deep mitosis together with the lack of maturation, makes me consider nevoid melanoma. Will love to read more expert opinions.

Nevoid Melanoma

Nevoid Melanoma.

There are some worrying features in this melanocytic proliferation that wouldn’t ensure me a good night’s sleep: a very small focus of pagetoid spread, nested atypical junctional component, small intradermal nests with pleomorphic cells clashing with surrounding cords of small cells, impaired maturation with depth, low pushing border and a mitotic figure in the deeper reaches.
Those findings really caught my eyes, so I favor nevoid melanoma.

My first impression is naevoid melanoma too.

Nevoid melanoma with Spitz features, pending immunostains to confirm (Ki67, HMB45).

Agree that this is a case made for CGH, especially if the stains are less than helpful, using the newer panels that are more sensitive for Spitzoid melanoma.
Histologic features that caught my eye:
1. Two populations of dermal melanocytes: large, more atypical Spitzoid melanocytes with gray cytoplasm, and smaller melanocytes with amphophilic cytoplasm, nuclear pleomorphism with focal intranuclear inclusions, which appear to be irregularly intermixed.
2. Elevated mitotic activity, concentrated paradoxically in the smaller, less-Spitzoid cell component, in both the upper dermis [mitosis in bottom left corner, in mid-left photo], and the deep edge [middle of bottom left photo].
3. Asymmetric junctional component of Spitzoid melanocytes with sparse pagetoid scatter and focal confluent lentiginous nesting [right side of top left photo].
[i] It bears some resemblance to the Spitzoid nevoid melanoma in Difficult Opinions case#15 (DO015). [/i]

[color=#1C2837][font=arial, verdana, tahoma, sans-serif][size=4]Nevoid Melanoma[/size][/font][/color]

I called this melanoma. Additional features were: patchy HMB45 positivity, without nice maturation, and focally more numerous Ki67 positivity, also without any obvious stratification.