Keratoacanthomatous Changes: Unifying the Histologic Spectrum of Actinic Granuloma

Abstract: Actinic granuloma (AG) manifests as annular plaques on sun-damaged skin. There remains no universal consensus on the nosology, etiology, or clinicopathologic criteria of AG as a distinct entity. Broadly, AG is characterized by granulomatous inflammation, multinucleated giant cells, elastophagocytosis, and the absence of mucin and necrobiosis. It is not uncommon, however, to encounter overlapping histological features of other granulomas, such as granuloma annulare and necrobiosis lipoidica, confounding the diagnosis of this controversial entity. Herein, we describe 2 cases of AG with features of granuloma annulare and necrobiosis lipoidica, supporting the concept of AG as a histologic spectrum. These 2 cases displayed dilated follicular infundibula and pseudoepitheliomatous hyperplasia analogous to changes in keratoacanthomas. These unique epithelial changes, in tandem with characteristic elastin alterations and clinical findings, are helpful and unifying features that permit accurate diagnosis of this controversial entity. Correspondence: Kiran Motaparthi, MD, Department of Dermatology, University of Florida College of Medicine, 4037 NW 86th Terrace, 4th floor, Springhill Room 4119, Gainesville, FL 32606 (e-mail: kmotaparthi@dermatology.med.ufl.edu). The authors declare no conflicts of interest. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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