Scleromyxedema in a patient with thyroid disease: an atypical case or a case for revised criteria?

Lichen myxedematosus (LM), commonly referred to as papular mucinosis, is a rare papular eruption defined by mucin deposition in the dermis. Scleromyxedema (SM) is a generalized papular and sclerodermoid form of LM. It is a progressive disease of unknown etiology with systemic manifestations that cause serious morbidity and mortality. Current criteria list thyroid dysfunction as an exclusion for the diagnosis of SM. Cases of LM associated with thyroid dysfunction have been defined as atypical. We describe a patient with uncontrolled hypothyroidism due to Hashimoto thyroiditis who subsequently developed a diffuse papular eruption with systemic signs and symptoms attributable to SM. Diagnostic workup, including laboratory studies and histologic specimens from the skin and muscle, were consistent with SM. Furthermore, our patient responded clinically to intravenous immunoglobulin (IVIg) and lenalidomide. We discuss the diagnostic criteria, differential diagnoses, and diagnostic challenges associated with LM in association with thyroid dysfunction. We propose that the presence of thyroid disease should not preclude the diagnosis of SM. Finally, we add to the case reports and series of successful treatments of SM with IVIg and lenalidomide.