Self-healing Cutaneous Mucinosis in Adulthood: The Adult Counterpart of the Juvenile Variant of the Disease?

Self-healing cutaneous mucinosis (SHCM) is an idiopathic localized cutaneous mucinosis mainly described in children and characterized clinically by an acute onset of papules and nodules that exhibit a spontaneous resolution in a period ranging from weeks to few months. Histologically, a diffuse mucin deposition in the dermis and/or hypodermis associated with a proliferation of spindle-shaped cells and some large epithelioid gangliocyte-like mononuclear cells is usually observed. An uncommon adult variant of SHCM has also been reported; however, the clinicopathological features described in these patients are extremely heterogeneous and differ significantly from the juvenile variant of the disease, often showing exclusively dermal involvement. We report a case of a 37-year-old female patient with multiple asymptomatic nodules located on the legs and arms that resolved spontaneously in a period of 2 years, showing the typical subcutaneous features of the juvenile variant of SHCM at the histological examination (ie, mucinous areas associated with dense bands of fibrosis containing arborizing thin-walled vessels, spindle-shaped fibroblasts, and some gangliocyte-like cells). To the best of our knowledge, this is the first report of SHCM showing the classic pattern of deep-seated subcutaneous involvement of the disease in an adult patient. We also review the cases of adult-onset SHCM reported in the literature.