Hereditary progressive mucinous histiocytosis (HPMH) is an extremely rare, benign, progressive, skin-limited disorder. It is characterized by the presence of multiple, persistent, skin-colored or red-brown papules that display prominent mucin histopathologically. Fewer than 20 cases of HPMH have been described to date. Prior to 2010, it was only seen in females, but recently, cases in males have been reported. Cases have been reported from the United States, Germany, Japan, Australia, Mexico, and France.

Onset of lesions is typically in childhood or adolescence. The papules progress in size and number throughout life. They are usually asymptomatic. Sites of predilection include hands and forearms, thighs, and face. While spontaneous resolution of nodules has been reported in the first few years of life, lesions of older children and adults do not spontaneously resolve.

HPMH is presumed to be inherited in an autosomal dominant manner. The genes and mechanisms involved are not well understood; however, the histiocytes of HPMH are thought to be of the monocyte / macrophage subset.