Hypergranulotic dyscornification: 30 cases of a striking epithelial reaction pattern.

Background: Hypergranulotic dyscornification (HD) is a rarely reported histological reaction pattern that may be observed in solitary benign keratoses.
Objective and Methods: We retrospectively reviewed all cases described as displaying "hypergranulotic dyscornification" at our institution between January 1st 1990 to September 1st 2018. We excluded cases that on retrospective review displayed changes of epidermolytic hyperkeratosis. We conducted electron microscopy (EM) of two lesions.
Results: Thirty cases were identified in our search. Eleven patients were men and 19 were women. Their mean age was 56.9 ± 21.2 years. In contrast to previous reports, we found that HD does not spare the head and neck area. Frequent clinical impressions were inflamed seborrheic keratosis, Bowen disease or inflamed verruca. The most distinctive histopathologic finding was the presence of a prominent granular layer with clumped perinuclear keratohyaline granules. Some cases had mounds of rounded, anucleate glassy eosinophilic corneocytes in the stratum corneum. We observed one case of incidental HD occurring in an epidermoid cyst. EM of HD showed dense perinuclear bands which appeared to match areas of positive staining by keratin immunohistochemistry, without evidence of pale cytoplasmic areas devoid of keratin filaments, characteristic of epidermolytic hyperkeratosis.
Conclusion: HD is a reproducible finding in some benign keratoses, probably because of abnormal keratinization. Awareness of this unique reaction pattern will help prevent misdiagnosis.
(© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)