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September 2007

Hyperpigmented Keratotic Nodules—Diagnosis

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Arch Dermatol. 2007;143(9):1201-1206. doi:10.1001/archderm.143.9.1201-e

Microscopic examination showed a cup-shaped deformity of the epidermis that was filled with a plug consisting of collagen, parakeratosis, and inflammatory exudate. The underlying epidermis was atrophic, but the adjacent epidermis was acanthotic. Dermal collagen at the base of the plug was almost perpendicular to the overlying epidermis. There was a sparse mixed inflammatory exudate around the upper dermal vessels.

The main histologic abnormality in perforating dermatoses is the transepithelial elimination of material from the dermis. There are 4 main types of primary perforating dermatoses: Kyrle disease, elastosis perforans serpiginosa, reactive perforating collagenosis, and perforating folliculitis. Perforating dermatoses have also been reported in association with chronic renal failure and diabetes mellitus. The term acquired perforating dermatoses has been used to describe them. The lesions are typically dome-shaped papules and nodules with a central keratotic plug. They have been considered a distinctentity from primary perforating dermatoses owing to their differences in clinical and histologic presentation from the original descriptions of the primary perforating dermatoses.13

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