Hematoxylin-eosin staining of a biopsy specimen of a large nodule that had been excised showed an exoendophytic crater-shaped neoplasm with keratin-filled channels lined by pale epithelium with a ground glass–like cytoplasm and surrounded by a sparse inflammatory infiltrate, characteristic of keratoacanthoma. Microscopic examination of the atrophic portion of the annular plaque on the left arm showed an epidermis with blunted rete ridges and an expanded papillary dermis with melanophages and slightly hyalinized collagen bundles, consistent with regression. Tissue cultures for bacteria, fungi, and atypical mycobacteria were unremarkable. The large plaque on the patient's left arm was thought to be consistent with keratoacanthoma centrifugum marginatum, and the diagnosis of KAVCS was made.
Multiple Hyperkeratotic Nodules on the Arms—Diagnosis. Arch Dermatol. 2003;139(10):1363-1368. doi:10.1001/archderm.139.10.1363-a