Original StudyCluster of Vacuolated Spinous Keratinocytes: A Clue to Cornoid Lamellation and a Case of Porokeratosis DisseminataKeller, Lauren P. DO*; Halim, Kareem MD†; Abedi, Syed M. MD‡; Liu, Wentao MD§; Gottesman, Silvija P. MD¶Author Information *Department of Dermatology, Sutter Health, Roseville, CA; †Department of Dermatology, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Lake Success, NY; ‡Department of Pathology, Lakeridge Health, Oshawa Campus, Oshawa, Ontario, Canada; §Department of Dermatology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China; and ¶Ackerman Academy of Dermatopathology, New York, NY. Correspondence: Silvija P. Gottesman, MD, Ackerman Academy of Dermatopathology, New York, NY 10016 (e-mail: firstname.lastname@example.org). The authors declare no conflicts of interest. The American Journal of Dermatopathology: September 2020 - Volume 42 - Issue 9 - p 673-676 doi: 10.1097/DAD.0000000000001614 Buy Metrics Abstract Cornoid lamella is a definitive diagnostic feature of porokeratosis, a disorder of keratinization that has various different clinical presentations. A tiered column of parakeratosis and a diminished granular layer with dyskeratotic keratinocytes at the column base are all useful and known features of cornoid lamellation. We have found a cluster of vacuolated spinous cells to be a reliable fourth feature of cornoid lamellation and a feature when present alone to be a reliable sign of impending cornoid lamellation on deeper sections. Furthermore, we present a novel clinical phenotype of disseminated papular porokeratosis with effective clinical response to combination of phototherapy, oral and topical retinoids, and topical vitamin D derivative, which too contained all 4 features of cornoid lamellation. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.