Some anogenital lesions diagnosed as seborrheic keratosis are actually condylomata acuminata. It can be difficult to distinguish these lesions on routine histologic sections.


Factors that may impact the diagnosis of seborrheic keratoses:

(1) The presence of chronic irritation can cause a seborrheic keratosis to take on reactive changes.

(2) The presence of a hereditary or acquired disorder associated with multiple seborrheic keratoses.


When to suspect that a skin lesion is a condyloma rather than a seborrheic keratosis:

(1) multiple anogenital lesions in a young person

(2) presence of dysplastic change in the epidermis


How to diagnose:

(1) demonstrate HPV DNA by in situ hybridization

(2) immunostaining pattern for MIB-1 or Ki-67


Seborrheic Keratosis


MIB-1 or Ki-67

staining limited to basal layer

staining involves the upper layers of the epidermis


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