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.