The invisible dermatoses.

It is understandable that clinically normal skin may show abnormalities when examined with the light microscope, but paradoxical that biopsy of a clinically significant skin disorder may show a histologic picture that looks like normal skin. From the perspective of the dermatopathologist, the invisible dermatoses are clinically evident skin diseases that show a histologic picture resembling normal skin. A strategy for approaching the problem of the invisible dermatoses is to first examine the epidermis for fungi, cornoid lamellae (disseminated superficial actinic porokeratosis), and absence of the granular layer (dominant ichthyosis vulgaris). The cutis is then studied for hyalin deposition (macular amyloidosis), mast cells, microfilaria, dermal melanocytosis, silver granules, and absence of sweat glands (anhidrotic ectodermal dysplasia). Special stains may be required to uncover conditions like anetoderma and nevus elasticus. Comparison of the specimen with normal skin may disclose atrophoderma, lipoatrophy, vitiligo, or café au lait spot. Finally, technical problems should be considered, including sampling errors and mixup of specimens, either by the clinician or the laboratory.