RESUMO
Infantile systemic hyalinosis (ISH) is a rare autosomal recessive disorder caused by a mutation in the ANTXR2 gene encoding a transmembranous protein involved in endothelial development. The ANTXR2 (also known as CMG2) locus is on chromosome 4q21. ISH is a common disorder in children of consanguineous parents in Arab countries. Symptoms of ISH manifest within the first months of life as progressive painful joint contractures and edema, hyperpigmentation of the skin, cutaneous nodules, persistent diarrhea with protein-losing enteropathy, and recurrent infections. Children affected by ISH often die undiagnosed in infancy. Histopathologic examination shows hyaline deposits in the skin, skeletal muscles, cardiac muscle, lymph nodes, adrenal glands, gastrointestinal tract, thyroid, and spleen. Hyaline deposits are the result of leakage of plasma components to the perivascular space owing to defective endothelial morphogenesis. ISH manifests most often in the facial region. Patients develop hypertrophy of labial and buccal tissues and massive gingival overgrowths, which impair oral food intake and maintenance of satisfactory oral hygiene. The differential diagnosis of ISH should consider juvenile systemic hyalinosis (an allelic variant of ISH), Winchester syndrome, systemic fibromatosis, stiff skin syndrome, lipoid proteinosis, mucopolysaccharidosis, sphingolipidosis, and mucolipidosis. This report describes a case of massive labial and gingival hypertrophy in a 6-year-old boy with ISH.