Treatment of the cutaneous manifestations of Gardner syndrome depends on the symptomatic or cosmetic nature and the location of the cysts. Treatment is similar to that used for ordinary cysts and involves excision  or use of intralesional steroids if the cysts are inflamed.
Antiestrogens and anthracycline-containing regimens may have a favorable radiological response rate against desmoid tumors and may be a viable option in some patients. 
Colectomy  is recommended for Gardner syndrome patients if 30 or more polyps are detected on colonoscopy or if biopsy results reveal dysplasia or malignant degeneration. Preserving the rectum results in a 25-59% chance of rectal carcinoma occurring in Gardner syndrome patients; therefore, rectal mucosal resection is recommended. Total gastroduodenectomy with pancreatic preservation may be desirable in some settings. 
Generally, cutaneous findings do not require treatment. Osteomas may require excision if they are severely deforming or if they interfere with function.
Also see the General Surgery article Gardner Syndrome.
In Gardner syndrome, polyps have a 100% risk of undergoing malignant transformation; therefore, surgical transection is indicated.
Females are at higher risk for thyroid carcinoma than males. Other neoplasms possible with Gardner syndrome include periampullary carcinoma, CNS tumors, osteosarcoma, chondrosarcoma, hepatoblastoma, and liposarcoma.
Desmoid tumors are a significant cause of the morbidity and mortality in those with Gardner syndrome; surgical procedures to excise them are complex.