Cronkhite-Canada syndrome (CCS) is a rare acquired syndrome of diffuse gastrointestinal polyposis, diarrhea, cutaneous pigmentation, alopecia, and onychodystrophy. Although CCS has been recognized worldwide, the majority of reported cases have been from Japan. While it can occur in both children and adults, CCS is usually seen in adults in the sixth decade of life. Males are more frequently affected than females.
 
CCS is characterized by chronic diarrhea that may be watery and intermittently bloody. It is accompanied by a protein-losing enteropathy, significant weight loss, iron deficiency anemia, and vitamin deficiencies. Other gastrointestinal symptoms include nausea, vomiting, and abdominal pain. Taste disturbances including dysgeusia or ageusia may occur. Polyps (hamartomatous and less frequently, inflammatory, hyperplastic, and adenomatous) may occur anywhere in the gastrointestinal tract, except for the esophagus.

Integumentary changes include lentigo-like or more diffuse hyperpigmentation (sometimes with hypopigmentation), nail dystrophy, and rapid-onset alopecia. While acute telogen effluvium has been implicated, recent evidence points to alopecia areata incognita (diffuse variant of alopecia areata) as being causative. These changes may worsen or improve with underlying disease activity.

The etiopathogenesis of CCS is unknown. Some cases have occurred in the setting of autoimmune diseases such systemic lupus erythematosus or rheumatoid arthritis, prompting inference of autoimmunity.

Untreated disease has a high mortality rate. Acute complications include gastrointestinal bleeding, intussusception, and sepsis. Chronically, CCS may predispose to osteoporosis. Malignant transformation of polyps in the colon (especially sigmoid and rectum) and stomach has been reported in a minority of cases.