Case Number : Case 1149 - 18th November Posted By: Guest

Epithelioid blue cell nevus/melanocytoma, to start.

Agree: epithelioid blue nevus/ melanocytoma.

Agree. Pigmented epithelioid melanocytoma. There appears to be a common blue nevus in the upper dermis above the epithelioid component.

Cellular epithelioid blue nevus

I find these lesions exceedingly difficult but given the biphasic character with dendritic component superficially would have to favour a cellular blue naevus. I will be interested to see if it is S100 negative as i would expect in blue naevus. Also interested to know if any molecular work-up was performed. Next question is whether I would advise a modest re-excision. I think I might not be prepared to take the risk as cellular blue naevi (buttock excepted) can recur and rarely undergo malignant transformation and i might just sleep a little easier!

It seems to have two cytologically distinct populations of melanocytes, so I go with combined nevus.

Epithelioid blue naevus.

Pigmented epithelioid melanocytoma

Agree with Epithelioid blue nevus. [size=4](A bulbous architecture in the deep dermis might suggest alternate classification as deep penetrating nevus).[/size][size=4] [/size]
[size=4] There is little inflammatory reaction, small to medium nucleoli, moderate pleomorphism with some senescent-type multinucleation; the lesion shows lack of mitotic activity in the superficial and deep fields instead of the very sparse mitotic activity expected. No significant epidermal component or maturation in the mid to deep portions.[/size]

This was an exceedingly difficult case. We did end up classifying this as a cellular blue nevus, but I must say that deep penetrating nevus and epithelioid blue nevus/pigmented epithelioid melanocytoma are both appropriate considerations. We did not favor these two latter designations because these cells seem to be spindled and nested than what we've seen in epithelioid blue nevi/pigmented epithelioid melanocytomas; the architecture is different from that of a deep penetrating nevus, which tends to have more of a columnar, wedge shaped silhouette. Molecular analysis did not favor melanoma. We did not do S100 (an excellent suggestion) but sent it to an expert who agreed with the interpretation of cellular blue nevus, although they too thought about deep penetrating nevus. We all recommended a modest re excision for the reasons suggested by Richard.