Definition:

Lipoid proteinosis (LP) is a rare autosomal recessive disorder characterized histologically by infiltration of periodic acid Schiff-positive hyaline material into the skin, upper aerodigestive tract, and internal organs. Infantile hoarseness is a common presenting feature of the disease due to infiltration of larynx. In two-thirds of the cases, voice changes are present at birth or in early infancy as the first manifestation. The disorder has been shown to result from loss-of-function mutations in the extracellular matrix protein 1 gene. The function of the protein extracellular matrix protein 1 gene is still unclear.