halo nevi containing large, epithelioid cells

HALO NEVI CONTAINING LARGE, ROUND EPITHELIOID CELLS

Large, round epithelioid cells are scattered within some nevi that have the histologic halo reaction or which have a clinical halo. If such cells form an expansile nodule or nodules, or if such cells constitute the majority of cells separated by lymphocytes in a thick lesion, minimal deviation melanoma, halo nevus type enters the differential diagnosis. Parenthetically, I do not know why the binucleate cells caught my eye; I have not made any controlled observations regarding these cells.

Two cases of halo nevi containing these cells are presented.

The first case is from a 22 year old male, and there was a halo clinically.

Low power view. The lesion was relatively symmetrical as viewed at scanning power (not illustrated). The junk by the cleft near the right side of the picture is India ink.
There were no areas having a fascicular pattern.

High power view of above. These cells have outlines that are more round than the usual epithelioid cells of Spitz' nevi. The large cells are widely separated by lymphocytes in this
example. Binucleate forms are present.

The second case also had a halo clinically and is from a 17 year old male.

Low power view.
The lesion was relatively symmetrical as viewed at scanning power (not illustrated).
There were no areas having a fascicular pattern.

High power view of the area in the rectangle. There is a mitosis (MIT) located in a cell in the basal layer of the epidermis. Mitoses in melanocytes solely in the basal layer are not indicative of malignancy. Some of the cells in the lower epidermis are larger than normal nevus cells but smaller than the largest cells in the dermis..

High power view that includes part of the lesion a little deeper to the area shown above. The histogenetic relationship of the large cells in the epidermis to the large cells in the dermis is problematical.

High power view from deeper in the lesion. Large, round epithelioid cells are widely separated by lymphocytes. Some of the large cells have two nuclei.

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	Low power view. The lesion was relatively symmetrical as viewed at scanning power (not illustrated). The junk by the cleft near the right side of the picture is India ink. There were no areas having a fascicular pattern.
	High power view of above. These cells have outlines that are more round than the usual epithelioid cells of Spitz' nevi. The large cells are widely separated by lymphocytes in this example. Binucleate forms are present.

	Low power view. The lesion was relatively symmetrical as viewed at scanning power (not illustrated). There were no areas having a fascicular pattern.
	High power view of the area in the rectangle. There is a mitosis (MIT) located in a cell in the basal layer of the epidermis. Mitoses in melanocytes solely in the basal layer are not indicative of malignancy. Some of the cells in the lower epidermis are larger than normal nevus cells but smaller than the largest cells in the dermis..
	High power view that includes part of the lesion a little deeper to the area shown above. The histogenetic relationship of the large cells in the epidermis to the large cells in the dermis is problematical.
	High power view from deeper in the lesion. Large, round epithelioid cells are widely separated by lymphocytes. Some of the large cells have two nuclei.