It is characterized by small papules on the backs of the hands, wrists, and extensor aspects of the distal forearms, with no further clinical or laboratory indications.
[2] Histologically, hematoxylin-eosin and Alcian blue staining show mucin accumulation in the upper reticular dermis, as well as collagen fiber separation due to hyaluronic acid deposition.
Histologically, DPLM has more diffuse and interstitial mucin deposition in the upper to mid dermis, at times with increased fibroblasts.
[2] In contrast, SHJCM is typified by an acute popular eruption that can combine to form linear infiltrated plaques on the face, neck, scalp, abdomen, and/or thighs.
Mucinous subcutaneous nodules on the face, sometimes associated with periorbital swelling, and on the periarticular areas are prominent features.
Localized lichen myxedematosus and scleromyxedema were once thought to be the same disease, but they are actually part of a spectrum in the context of primary cutaneous mucinoses.
Scleromyxedema's classic histopathologic findings are a microscopic triad of mucin deposition, fibroblast proliferation, and fibrosis, or, in rare cases, an interstitial granuloma annulare-like pattern.
[8] Scleromyxedema, unlike APPM, occurs in association with monoclonal gammopathy and can have a wide range of systemic manifestations, including neurologic, rheumatologic, pulmonary, and cardiovascular indications.