Significance of incidental desmoids identified during surgery for familial adenomatous polyposis

The behavior of intra-abdominal desmoids in familial adenomatous polyposis is incompletely understood. Findings range from typical mass lesions to flat sheets, termed the desmoid reaction or desmoid precursor lesion. The latter often are incidental findings of uncertain significance. The study was designed to describe the natural history of incidental intra-abdominal desmoid tumors with particular reference to the desmoid reaction.

Patients who underwent laparotomy for familial adenomatous polyposis at the Cleveland Clinic Foundation were identified. The incidence of incidental intra-abdominal desmoid tumors was determined by review of operative records. Intra-abdominal desmoid tumors were classified as mass lesions if three-dimensional or desmoid reaction if two-dimensional. The incidence of clinically apparent intra-abdominal desmoid tumors (typical mass lesions on physical examination or cross-sectional imaging in symptomatic patients) was determined by chart review. The incidence of clinical intra-abdominal desmoid tumors between groups was compared by Fisher's exact test.

A total of 266 patients (153 females; median age, 26 (range, 9-63) years) underwent abdominal surgery for familial adenomatous polyposis. Incidental intra-abdominal desmoid tumors were identified in 34 patients: 8 at the index surgery and 26 at relaparotomy. These lesions influenced the planned procedure in eight cases (26 percent), including preventing ileoanal pouch in 3 of 19 patients in whom this was intended. The median follow-up from the time of identification of intra-abdominal desmoids was 42 (range, 2-178) months at which point four patients (11 percent) had developed clinical intra-abdominal desmoid tumors. There was no significant difference in incidence of clinical intra-abdominal desmoid tumors between mass and desmoid reaction groups ( P = 0.27).

Incidental intra-abdominal desmoid tumors are a common finding at relaparotomy in patients with familial adenomatous polyposis. These lesions influence planned surgery in a minority of cases. Desmoid reaction may have little bearing on the subsequent development of clinically significant intra-abdominal desmoid tumors.