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Gardner syndrome (GS) is a genetic disease characterized by polyps of the colon, multiple osteomas, multiple dense bone islands, multiple impacted teeth, and skin and soft tissue tumors.

https://doi.org/10.1007/s11282-016-0235-y

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Gardner syndrome is a variant of familial adenomatous polyposis (FAP), characterized by the triad of colonic adenomatous polyps, extracolonic tumors and soft tissue lesions.

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It is a heritable cancer predisposition syndrome with autosomal dominant inheritance, caused by mutations in the APC gene on chromosome 5q21.

Etiology

Feature	Description
Gene	APC (adenomatous polyposis coli)
Chromosome	5q21
Inheritance	Autosomal dominant
Penetrance	Nearly complete (variable expressivity)

Clinical Features

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Characteristic triad of colonic adenomatous polyps, extracolonic tumors and soft tissue lesions.

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I. Gastrointestinal Findings

Hundreds to thousands of adenomatous colorectal polyps
- Onset: Teen years
- Cancer risk: ~100% without colectomy
Small bowel polyps, especially in duodenum and jejunum
Gastric fundic gland polyps

II. Extracolonic Manifestations

Category	Findings
Desmoid tumors	Aggressive fibrous tumors (mesentery, abdominal wall)
Osteomas	Most commonly in mandible, skull, long bones
Epidermoid cysts	Face, scalp, and extremities
Dental anomalies	Supernumerary teeth, impacted teeth
‣	Congenital hypertrophy of the retinal pigment epithelium (seen on fundoscopy)
Thyroid carcinoma	Particularly papillary subtype
Liver tumors	Hepatoblastoma (especially in children)

Diagnostic criteria

Diagnostic criteria:

Gardner syndrome is clinically diagnosed when:

There are multiple colorectal adenomatous polyps AND