F-18 FDG PET/CT Findings of Spontaneous Mesenteric Fibromatosis in a Patient with Gardner’s Syndrome

Gardner’s syndrome (GS), a variant of familial adenomatous polyposis, is an autosomal dominant disease. Originally, Gardner described a syndrome consisting of hereditary intestinal polyposis with osteomas and multiple cutaneous and subcutaneous lesions [1] (Figs. 1 and 2). The syndrome was later modified by the addition of other features, such as dental abnormalities, abdominal fibromatosis, and a number of malignant tumors. The principal cutaneous lesions that have been described in GS are epidermoid cysts. Other cutaneous lesions include fibromas, lipomas, leiomyomas, neurofibromas, and pigmented skin lesions [2]. Fibromatoses are histologically benign, but locally aggressive fibrous tumors consisting of mature fibroblasts within an extensive collagen matrix. Most cases are sporadic, but there is a clear association with familial adenomatous polyposis and GS, suggesting a link with a mutation of the APC gene on chromosome 5q22 [3]. Fibromatosis occurs in 3.5%–29% of patients with GS, and is more likely to be multiple and to involve the mesentery and abdominal wall rather than being an isolated form [4, 5]. Clinically, fibromatosis presents as a painless firm soft tissue mass. Most cases of fibromatosis are believed to be precipitated by surgical trauma; however, a few cases of spontaneous occurrence have been reported [6]. In our patient, no history of abdominal surgery or trauma was present. In addition, an abdominal CT obtained 2 years ago revealed no abnormality.

Fig. 1.

A 20-year-old man was admitted to oral surgery with a dental problem. A panoramic radiograph showed multiple osteomas in the right angle and anterior portion of the mandible with dental abnormalities (impacted or unerupted teeth, and supernumerary teeth). Surgery was performed, and a biopsy confirmed osteomas

Fig. 2.

The patient had a history of excision of a mass on the back 4 years previously. (a–c) Transverse MR images showed low-signal intensity on T1-weighted image (WI), heterogenous high-signial intensity on T2WI, and marked enhancement on contrast-enhanced T1WI. Biopsy confirmed a neurofibroma

Although the radiological features of fibromatosis on CT or MR have been described in the literature, F-18 FDG-PET or PET/CT findings are rarely reported [7–10]. The F-18 FDG uptake in patients with fibromatosis ranged from low to moderate grade and was generally heterogenous with a few tiny foci of relatively intense uptake or relatively homogenous. The areas of higher FDG metabolism are likely to represent more cellular and mitotically active areas [7]. Mesenteric fibromatosis has similar findings to extra-abdominal lesions [7, 9] (Fig. 3).

Fig. 3.

Routine laboratory studies for dental surgery showed abnormal liver function tests. The patient was referred to the Gastroenterology Service. Computed tomography (CT) of the abdomen demonstrated a large soft tissue mass in the right lower quadrant (RLQ), suggesting a small bowel lymphoma with intussusception. A F-18 FDG PET/CT was performed to assess the tumor extent and determine the appropriate site of biopsy. (a) A maximum-intensity-projection (MIP) image showed an oval-shaped, moderate-grade FDG uptake interspersed with a few tiny foci of relatively intense uptake in the RLQ of the abdomen (arrow; SUVmax, 5.6). (b, c) Coronal (fused PET/CT) and transverse (upper image, fused PET/CT; middle image, contrast enhanced-CT; low image, PET) images through the mass revealed an 8 × 6-cm, enhanced, soft tissue mass with moderate-grade FDG accumulation in the RLQ. Upper and lower gastrointestinal endoscopy revealed multiple adenomatous polyps in the colon. Laparotomy revealed a firm mass in the mesentery. Biopsy confirmed a fibromatosis (also known as a desmoid tumor). The patient was diagnosed with Gardner’s syndrome, with multiple osteomas in the mandible, dental abnormalities, mesenteric fibromatosis, multiple colonic polyps, and neurofibroma