Case Number : Case 548 - 16 July Posted By: Guest

[b]My diagnosis is Pigmented Epithelioid melanocytoma (no mitosis, ulceration or junctional component). DD animal type melanoma. [/b]

Epithelioid blue naevus.

[b]Also epithelioid blue nevus is in the differntial diagnosis.[/b]

My preferred diagnosis based on lack of infiltrative deep margins, good circumscription/ symmetry and lack of significant atypia/ mitoses, is Epithelioid Blue nevus.

However I think this would fall into the controversial pigmented epithelioid melanocytoma category which encompasses Epithelioid Blue nevus and Animal-type melanoma!

Blue nevus vs pigmented epitheloid melanocytoma

Pigmented Epithelioid melanocytoma

Epithelioid blue nevus

Epithelioid blue nevus.

I think that it is not possible to make a distinction between epithelioid blue nevus and pigment synthesizing melanoma on these images. They could represent either. I believe however that there were mitoses in the original section but the slide that I photographed was a recut devoid of mitotic activity. The case was diagnoses as a pigment synthesizing melanoma. I have no follow-up information.

[size=4][font=arial,helvetica,sans-serif][color=#231F20]The blue naevus is characterized clinically by its colour (Tyndall effect, [color=#000000]the shorter wavelength of light [blue] is scattered/reflected by the deep brown pigment[/color]) and symmetrical shape and must be differentiated from other dermal melanoses. [/color][color=black]The term ‘pigmented epithelioid melanocytoma’ is used by some for a ‘low-grade melanocytic tumour with metastatic potential indistinguishable from animal-type [equine - resembling the usually benign tumours seen in many grey horses] melanoma and epithelioid blue naevus’. When in doubt the lesion is managed as for melanoma. [/color][/font][/size]

[color=#000000][url="http://www.ncbi.nlm.nih.gov/pubmed?term=Antony%20et%20al%20%20%E2%80%98pigment%20synthesizing%20melanoma"]Antony et al[/url] in the United Kingdom have suggested ‘pigment synthesizing melanoma’ as a preferable term to ‘pigmented epithelioid melanocytoma’.[/color]