F1Ch34b: This is a representative field from a pilomatrixoma; germinative epithelium is represented in variable patterns. To the right, the cells mostly are small with round nuclei, prominent nucleoli, and scanty cytoplasm; they qualify as a variant of matrical cells. Along the interface with keratinized debris, a single row of flattened cells separate the small round cells from the keratinized debris. Perhaps, this row of cells corresponds to the “cuticle” of the inner root sheath of a normal follicle. To the left of the population of small, round cells, there is a cluster of uniform cells that have pale, amphophilic cytoplasm and nuclei of intermediate size; nucleoli are prominent but uniform; a match for this population of cells can be identified in a normal anagen hair bulb. Above the blue arrows, polygonal acidophilic cells have numerous, uniformly small, brightly acidophilic granules in their cytoplasm; the granules are small, and uniform in size; the cytologic features are not those of the cells of Huxley’s layer. The acidophilic cells seem to stream from left to right. Red arrows identify a whorl of mature squamous cells in what is otherwise a population of germinative cells.
|