Case Number : Case 1195 - 21th January Posted By: Guest

My diagnosis is Spitz naevus.

Agree with spitz nevus, with active bottom inflammation consistent with "halo reaction" likely clinically noticed; due to extension of the junctional component I wonder whether this may histologically qualify for a dysplastic "spark" nevus

I am not an expert when it comes to atypical melanocytic lesions, but I find here some worrisome features: age, large somehow confluent dermal nests in figs 6,7,9 and 10 with atypia (nuclear pleomorphism). When u look at fig 6, u see the marked asymmetry of the dermal component.....Yet there are other- wise typical features of SN. Could it be a melanoma evolving in a Spitz nevus? Or an atypical SN/ Spitzoid neoplasm with uncertain malignant potential. If this is my case, I will definitely ask for additional work up.

Melanoma.

There's a component on the left of the Image 6, detailed at high power view on Images 7, 9 and 10, which differs from the rest of this spitzoid lesion. This component is comprised of pleomorphic epithelioid cells arranged in nests that vary in size and shape. Unlike the nests of the rest of the lesion, the nests of this component do not show cupping, to wit, the artifactual clefting between the upper edges of the junctional nests and the epidermis above them. Also, this component is hyperpigmented with dusty melanin and have pagetoid spread without epidermal hyperplasia. So, I think this a melanoma arising in a pre-existing Spitz’s nevus.

Melanoma developing in Spitz's nevus.

[size=4]This appears to be a fence-sitter of a Spitzoid neoplasm. Depending on one's choice of (heavily overlapping) criteria I think one can argue convincingly for either dysplastic/atypical compound Spitz nevus vs. Spitzoid melanoma. On H&E alone, I'll opine for dysplastic Spitz arising in pre-existing nevus, cannot rule out Spitzoid melanoma. I would customarily get P16 and Ki67 immunostains, as these may be helpful for differentiating benign-vs-malignant Spitz lesions.[/size]

[size=4] Supporting dysplastic: no definitive mitotic activity in either dermal or epidermal melanocytes, smudgy chromatin with small nucleoli, low-level pagetoid scatter, overall asymmetry, extension of junctional component beyond dermal component (shouldering).[/size]
[size=4]Supporting malignant: Plasma cell component in inflammatory infiltrate, heterogeneity of dermal cytology, and older age bracket (40 years). [/size]

Atypical spitzoid tumor. I think one cannot be certainly sure of this tumor's behavior based solely on histology.

Background compound spitz naevus with beutiful Kamino bodies. Separate distinct suspicious epithelioid clone uncertain for malignancy but of low risk for metastasis (thin, small area).

Thank you all for the detailed comments, I learned a lot from your discussion. We went through exactly the same process thinking whether it is a conventional spitz nevus or melanoma arising from it and based on the age and atypical features we classified it as atypical spitz nevus and recommended wider excision but no sentinel node biopsy.