Small bowel obstruction from multifocal infiltrative mesenterial desmoid tumours in Gardner syndrome

Clinical History

Young adult female with history of previous subtotal colectomy for familial adenomatous polyposis (Gardner syndrome) 5 years earlier, hospitalised due to intestinal subocclusion including ingravescent abdominal pain, nausea and vomiting. Moderate pain evoked during abdominal palpation without signs of peritonism. Mild anaemia (Hb 10, 1 g/dL).

Imaging Findings

Plain abdominal radiographs (Fig. 1) obtained during Emergency Department stay showed fluid-filled overdistended stomach and moderately distended jejunal loops with air-fluid levels consistent with proximal small bowel obstruction.
Following gastric emptying by means of nasogastric tube placement, contrast-enhanced MDCT was requested to investigate entity and underlying cause of intestinal obstruction [Fig. 2).
At least two distinct infiltrative soft-tissue masses with ill-defined margins were detected, respectively at the mesenteric root and in the distal mesentery towards the right iliac fossa. The largest, proximal lesion encased the patent mesenterial vessels causing a “sandwich sign” CT appearance; furthermore, jejunal tethering causing upstream small bowel obstructive dilatation with air-fluid levels was observed. Minimal peritoneal fluid was present. Radiologic diagnosis was enteric subocclusion from multiple, infiltrative mesenterial desmoid tumours in Gardner syndrome.
Surgical consultation excluded operative treatment options. Long-term medical treatment including Tamoxifen was prescribed.

Discussion

Familial adenomatous polyposis (FAP) and its variant Gardner syndrome (GS) including extracolonic manifestations such as osteomas, epidermoid cysts, dental and retinal abnormalities, are well-known autosomal-dominant inherited conditions characterised by innumerable colorectal adenomas with inevitable malignant transformation [1, 2]. Prophylactic subtotal colectomy or proctocolectomy is the treatment of choice and eliminates the risk of colorectal adenocarcinomas. [3].
Affecting 10-30% of GS/FAP patients, desmoid tumours (DTs) constitute the major cause of morbidity and mortality, usually developing 2-5 years following restorative proctocolectomy [2-6].
Histologically, DTs (also termed aggressive fibromatosis) are benign mesenchymal proliferations of fibroblastic cells and abundant collagen. DTs in FAP/GS may develop extra-abdominally, within the abdominal wall or most commonly in the mesentery or retroperitoneum, are locally aggressive proliferations with an unpredictable behaviour, invade contiguous structures and usually recur postoperatively, without distant metastatisation [3, 6, 7].
Presentation includes abdominal pain, sometimes diarrhoea, rarely a palpable mass; variable small-bowel obstruction is present in 60% of cases [7, 8].
Cross-sectional multiplanar modalities allow accurate definition of size, extent and relationship with adjacent structures. CT features show considerable heterogeneity regarding density, margins and modifications over time, even between different lesions in the same patients. Often multiple (up to 3 lesions) and largely variable in size, mesenteric DTs may appear are large demarcated soft tissue masses; conversely other lesions (such as in our patient) appear as infiltrative, poorly defined “whorled” fibrotic thickening within the mesenteric fat, isoattenuating to muscle. Smaller lesions are subtle and best appreciable with bowel opacification. Contrast enhancement is variable, usually poor. DTs often compress or infiltrate adjacent enteric loops or ureters, leading to intestinal obstruction or hydronephrosis. Differential diagnosis includes other causes of mesenterial soft tissue masses [5, 6, 8, 9].
Large size, multiplicity, extensive bowel or ureteral involvement, growth on serial scans represent poor prognostic signs [6-8].
At MRI, DTs appear as mass-like or ill-defined T1-hypointense, heterogeneously T2 hyperintense soft tissue masses, sometimes with low signal intensity internal areas reflecting abundant collagen or myxoid stroma and variable contrast enhancement [7-9].
These benign but aggressive, tumours deserve conservative approach: first-line therapy with tamoxifen or sulindac restrains their growth in 30-50% of patients [2, 3]. Surgery for intra-abdominal DTs may be hazardous involving major enteric resection, with a very high (75-85%) recurrence rate after debulking, therefore should be reserved to selected patients is used to manage obstructive complications [4, 9].

Differential Diagnosis List

Final Diagnosis

Multiple infiltrative mesenterial desmoid tumours causing bowel obstruction

URL:	https://www.eurorad.org/case/9588
DOI:	10.1594/EURORAD/CASE.9588
ISSN:	1563-4086