Disseminated superficial porokeratosis with amyloid deposits.

We report a 65-year-old Caucasian man who exhibited a disseminated superficial porokeratosis. Histological examination with haematoxylin and eosin stain revealed the presence of dermal deposits of an eosinophilic amorphous material that stained positively with crystal violet and showed bright yellow fluorescence with thioflavin-T under the polarizing microscopy, indicating that it was amyloid. Colloid bodies from porokeratotic lesions can degenerate into amyloid, but it is not usually detected with haematoxylin and eosin stains because of its small quantity. Probably amyloid deposits could be detected more frequently in porokeratosis if histochemical techniques were carried out in a routine way.