Histopathologic characteristics of scleromyxedema: A study of a series of 34 cases.

Background Few histologic studies describe the histopathologic aspects of scleromyxedema. Objective We sought to describe the histopathologic and immunohistochemical features of scleromyxedema in a large series of patients. Methods We studied all the cases with scleromyxedema diagnosed between 2000 and 2014 at participating centers. Sections with hematoxylin-eosin and special stains were examined. Immunohistochemistry for CD3, CD4, CD8, CD20, CD68, and factor XIIIa was performed in 10 cases. Results A total of 44 skin biopsy specimens from 34 patients were reviewed. Two different histopathologic patterns were observed: the classic microscopic triad (dermal mucin deposition, fibroblast proliferation, fibrosis) was identified in 34 specimens, whereas an interstitial granuloma annulare–like pattern was found in 10 specimens. A superficial perivascular infiltrate with T lymphocytes was found in all specimens whereas an interstitial proliferation of CD68 + epithelioid cells was identified in the 10 specimens with an interstitial granuloma annulare–like pattern. Elastic fibers were largely lost, explaining the redundant folds of the disease. Limitations This was a retrospective study. Conclusions Scleromyxedema shows 2 histopathologic patterns, including the classic type with the microscopic triad of mucin, fibroblast proliferation and fibrosis, and an interstitial granuloma annulare–like pattern. Recognition of these histologic presentations expands the spectrum of scleromyxedema and highlights the difficulty in diagnosing this disabling condition in the absence of a clinicopathological correlation.