CT APPEARANCES OF DESMOID TUMORS IN FAMILIAL ADENOMATOUS POLYPOSIS - FURTHER OBSERVATIONS

Intra-abdominal desmoid tumours represent a major cause of morbidity a nd mortality in patients with familial adenomatous polyposis (FAP), an d such patients are also liable to develop musculoskeletal desmoids. W e have reviewed the CT appearances of 44 desmoid lesions (28 intra-abd ominal and 16 musculoskeletal) in 20 patients with FAP. We found a con siderable heterogeneity in the CT appearance of musculoskeletal and in traabdominal desmoids, with respect to their density, definition and c hange in size or density on follow-up, not only between different pati ents but also in patients with multiple lesions, who rarely showed ide ntical appearances of all lesions. In some cases, mesenteric tumours m ay initially present as ill-defined soft tissue infiltration of mesent eric fat, becoming larger and more mass-like with time. On medical tre atment, shrinkage was seen infrequently in musculoskeletal desmoids, a nd not at ah with mesenteric lesions. CT evidence of bowel involvement by intra-abdominal lesions was frequent, most commonly appearing as ' tethering' or encasement of bowel loops. The presence of a large mesen teric mass (>10 cm diam.), multiple mesenteric masses, extensive small bowel involvement and/or bilateral hydronephrosis were associated wit h ultimate death.