Track: Case Reports

Abstract:

Scleromyxedema is an entity within the realm of primary cutaneous mucinoses associated with high mortality and limited treatment availability. To meet parameters for diagnosis, the following four criteria must be met: (1) generalized papular and sclerodermoid eruption, (2) mucin deposition, fibroblast proliferation, and fibrosis, (3) monoclonal gammopathy, and (4) absence of thyroid disease. The classical histopathology of scleromyxedema shows spindled fibroblasts in the reticular dermis, dermal mucin, interstitial deposition of mucin, and epidermis, which can present on the spectrum of atrophic to acanthotic.

This is a case of an 80-year-old man who presented with elevated blood protein levels in addition to stiffness, swelling, feelings of taut skin, numbness, and tingling. Physical examination revealed numerous eruptions on the distal phalanges, and serum protein electrophoresis revealed elevated serum free light chains. Thyroid labs were unremarkable.

Skin punch biopsy of the forearm showed minimal pathologic changes in the superficial dermis and an interstitial mononuclear cellular infiltrate associated with degenerated collagen bundles and fibrotic changes in the deep dermis. Alcian blue special stain showed increased dermal mucin within the areas of degenerated collagen. CD68 immunohistochemical stains highlighted the surrounding histiocytes.

Given the clinical presentation of the patient with the unique histopathological correlation, we believe this represents a case of granulomatous scleromyxedema, rather than deep granuloma annulare, and represents a potential diagnostic pitfall. The patient underwent hematologic workup and is considered to have monoclonal gammopathy of undetermined significance (MGUS).

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Margaret Coates