Bannayan-Riley-Ruvalcaba syndrome (BRRS) is a rare autosomal dominantly inherited PTEN hamartoma-tumor syndrome. Patients often demonstrate the triad of macrocephaly, genital lentiginosis, and intestinal polyposis.

Characteristic mucocutaneous signs include, in decreasing frequency, vascular malformations, lipomas, genital lentiginosis, facial verrucae-like or acanthosis nigricans-like lesions, and multiple acrochordons of the neck, axilla, and groin.

BRRS typically presents at birth or in early childhood. Affected neonates often have a head circumference, birth weight, and birth length above the 97th percentile for their gestational age. Developmentally, children may have intellectual disability, mild psychomotor delay, hypotonia, seizures, and proximal muscle weakness.

Almost half of patients develop intestinal hamartomatous polyposis, which is associated with rectal bleeding, diarrhea, intussusception, and/or anemia. These polyps are believed to have no associated increased risk of gastrointestinal malignancy.

Musculoskeletal abnormalities consisting of joint hyperextensibility, scoliosis, and pectus excavatum are common, along with ocular findings comprising prominent Schwalbe's lines and corneal nerves.

BRRS and Cowden disease both involve germline mutations in the PTEN tumor suppressor gene and share similar clinical features, including a predisposition to developing thyroid, endometrial, breast, and renal cancer.