Cutaneous mucinosis of infancy (CMI), also known as papular mucinosis of infancy, is a subtype of localized lichen myxedematosus. This primary dermal mucinosis is a very rare disorder observed in young children. In cases reported in the literature, lesions may be observed at birth or shortly thereafter. CMI appears to affect boys and girls equally.

Clinically, CMI presents as asymptomatic and variably sized skin-colored to erythematous papules and/or dermal plaques. They are most commonly found on the trunk and proximal extremities, and less frequently on the neck, hands, and digits.

As a subtype of localized lichen myxedematosus, CMI does not involve visceral organs. The disease course is variable and may be self-limited or progressive. CMI is typically not associated with rheumatologic disease, and the presence of thyroid disease and monoclonal gammopathy should be excluded.