desmoplastic trichoepithelioma having pilomatrical differentiation

DESMOPLASTIC TRICHOEPITHELIOMA WITH GHOST (SHADOW) CELL PRODUCTION AND MINIMAL PROXIMAL FOLLICULAR DIFFERENTIATION (PILOMATRICAL DIFFERENTIATION)

The combination of microcysts and thin strands of basaloid epithelium wrapped by collagen is characteristic of desmoplastic trichoepitheliomas. The epithelial component of desmoplastic trichoepitheliomas resembles the mantle portion of the follicle, but other follicular constituents may be present to a limited degree. The case shown below has proximal follicular components, including abortive hair cortical keratin production manifested by ghost (shadow) cell production of the type found in pilomatricomas. Ghost (shadow) cells are found uncommonly in other lesions such as basal cell carcinomas and a peculiar type of small cyst of follicular derivation.

From the left cheek of a 71 year old male:

Scan power view. The tumor is found in all levels of the dermis. Microcysts, tiny foci of calcification, and small strands of epithelium are visible at this magnification.

Low power view taken from another section on the same slide. Note the two microcysts, a few small strands of epithelium, and foci of calcification. This type of calcification, in this setting, is indicative of calcified keratin. One of the microcysts has a pointed indentation in the wall at the 12:00 o'clock position.

High power view of an area within which thin strands of epithelium are occasionally wrapped by small collagen fibers. This combination is very characteristic of desmoplastic trichoepithelioma.

Medium power view of an area within which there are elongate collections of ghost cells (lower part of the field). The clusters of basaloid cells in this field are wider than some noted elsewhere and are associated with more cellular fibroblastic stroma. The broad clusters of basaloid cells associated with fibroblastic stroma can be seen in basal cell carcinomas and this combination prompted me to recommend a complete excision of this tumor.

High power view of a cluster of ghost cells plus a structure containing elements of a hair bulb and the proximal or trichogenic portion of a follicle. This combination is seen in some pilomatricomas.

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	Scan power view. The tumor is found in all levels of the dermis. Microcysts, tiny foci of calcification, and small strands of epithelium are visible at this magnification.
	Low power view taken from another section on the same slide. Note the two microcysts, a few small strands of epithelium, and foci of calcification. This type of calcification, in this setting, is indicative of calcified keratin. One of the microcysts has a pointed indentation in the wall at the 12:00 o'clock position.
	High power view of an area within which thin strands of epithelium are occasionally wrapped by small collagen fibers. This combination is very characteristic of desmoplastic trichoepithelioma.
	Medium power view of an area within which there are elongate collections of ghost cells (lower part of the field). The clusters of basaloid cells in this field are wider than some noted elsewhere and are associated with more cellular fibroblastic stroma. The broad clusters of basaloid cells associated with fibroblastic stroma can be seen in basal cell carcinomas and this combination prompted me to recommend a complete excision of this tumor.
	High power view of a cluster of ghost cells plus a structure containing elements of a hair bulb and the proximal or trichogenic portion of a follicle. This combination is seen in some pilomatricomas.