Lipoid proteinosis (LP) is a rare, autosomal recessive disorder due to a loss-of-function mutation of the gene coding for the extracellular matrix protein 1 (ECM1). Mutations in ECM1 are thought to cause extensive deposition of noncollagenous proteins and glycoproteins in the skin, oral mucosa, larynx, and brain. Those of European ancestry are most often affected, with no predilection between the sexes.

The disorder presents early in life and is slowly progressive. The first clinical sign is often a weak cry or hoarseness, with the hoarseness persisting throughout life. Skin changes consisting of vesicles and hemorrhagic crusts on the face and extremities with resultant scarring generally appear during the first 2 years of life. Subsequent skin changes include the formation of infiltrated papules, plaques, and nodules on the face, axillae, and scrotum with verrucous lesions on the elbows, hands, and knees. There can be diffuse infiltration of the tongue, frenulum, and oropharynx along with dental anomalies. Neurologic manifestations include behavioral or learning difficulties and seizures. Mortality is usually related to laryngeal obstruction in infancy or to associated epilepsy.