Histopathologic Spectrum of Scleromyxedema: Classic and Granulomatous Patterns With Emphasis on Eosinophilic Infiltrates and Eccrine Gland Proliferation as Diagnostic Masqueraders.

Scleromyxedema is a rare, chronic cutaneous mucinosis defined histopathologically by a triad of dermal mucin deposition, fibroblast proliferation, and dermal fibrosis. However, additional underrecognized histopathologic patterns or findings may complicate diagnosis and lead to misclassification. A retrospective review of 22 biopsy-confirmed cases of scleromyxedema was performed to characterize both classic and uncommon histopathologic variants of scleromyxedema, with emphasis on patterns that may obscure or mimic other dermatologic entities. All cases were evaluated for mucin, fibrosis, fibroblast proliferation, inflammatory infiltrates, granulomas, eosinophilic infiltration, and eccrine gland hyperplasia using hematoxylin and eosin and special stains, with immunohistochemistry as it was needed. Sixteen cases (72.7%) demonstrated the classic histologic triad. In contrast, 6 cases (27.3%) showed a granulomatous pattern characterized by interstitial collections of CD68+ histiocytes, multinucleated giant cells, sparse lymphocytes, and mucin, but lacked the full classical triad-posing a risk of misdiagnosis as granuloma annulare or other granulomatous dermatoses. Eosinophilic infiltrates were identified in 4 cases (18.2%), and eccrine gland hyperplasia in 2 cases (9.1%). Both findings coexisted with the classical triad and may mimic inflammatory or adnexal conditions. Scleromyxedema presents with broader histopathologic variability than classically recognized. The granulomatous pattern, which may lack the defining triad, can obscure diagnosis without clinical correlation. In contrast, eosinophilic infiltration and eccrine gland hyperplasia, though infrequent, typically coexist with classic features and should be recognized as part of the histologic spectrum. Awareness of these variants is essential to avoid misdiagnosis and ensure accurate clinicopathologic interpretation.