42 Dermatopathology

patch, resembling a solar lentigo. Other lesions are erythematous. Many appear to represent a histo-logic variant of solar lentigo, others of Bowens dis-ease. The cells of some lesions have been shown to be aneuploid, and no histological features predict which lesions demonstrate aneuploid populations. Because of this, many clinicians prefer to destroy any remaining lesion by means of cryotherapy.

Inverted follicular keratosis (IFK)

Key features Endophytic lesion resembling an expanded hair

follicle Squamous eddies

The outline of the epithelial column is smooth, with no evidence of jagged invasive growth

True inverted follicular keratoses are benign follicular proliferations unrelated to human pap-illomavirus infection. Multiple lesions may be associated with Cowdens syndrome. Follicular warts may sometimes have squamous eddies and resemble IFKs.

Warty dyskeratomaKey features Endophytic growth Acantholytic dyskeratotis

Overlying parakeratotic crust may be present

Two types of dyskeratotic cells are noted. Corps ronds are round dyskeratotic cells that stain pale pink to red, and may have a wide clear halo sur-rounding the nucleus. Grains are flattened ba-sophilic dyskeratotic cells. Either or both may be present. Some lesions are crateriform; others resemble expanded hair follicles.

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Figure 2-23 Large cell acanthoma

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Figure 2-24 Inverted follicular keratosis

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