There was hyperkeratosis with a discrete column of parakeratosis (cornoid lamella). Beneath the cornoid lamella, the granular layer was absent, and keratinocytes were vacuolated and disorganized. A scant dermal mononuclear cell infiltrate was present (Figure 3).
Disseminated superficial actinic porokeratosis is characterized by multiple (sometimes >100), slowly expanding (up to 1 cm), bilateral plaques with raised, hyperkeratotic borders and central atrophy, erythema, hyperkeratosis, or pigmentation. The lesions manifest by the third to fourth decade of life and are located symmetrically on sun-exposed areas. Typically, the upper and lower extremities are involved, with sparing of the palms, soles, and mucous membranes.1,2 Nearly one third of patients will experience stinging or pruritus. Almost half have exacerbations during the summer months.3 The lesions may be subtle and missed clinically or mistaken for multiple actinic keratoses. The clinical differential diagnosis also includes flat seborrheic keratosis, stucco keratosis, atrophic annular lichen planus, disseminated granuloma annulare, and eruptive syringoma.2
Multiple Chronic Lesions With Peripheral Scale. Arch Dermatol. 1998;134(6):743-748. doi: