Mesenteric Fibromatosis: A Rare Cause of Acute Abdominal Pain

Abstract

A 45-year-old man, with a previous history of astrocytoma, presented with diffuse abdominal pain. A CT scan was non-specific and the pain worsened; his abdomen became peritonitic on examination. An exploratory laparotomy was performed, and a large small bowel mesenteric mass was found together with an associated haematoma. Subsequent histology showed the tumour to be a benign fibromatosis, and the patient recovered uneventfully. There were no reports in the literature of any association between astrocytomas and fibromatosis. Mesenteric fibromatosis is a rare tumour often associated with Gardner's syndrome. It can present in a multitude of ways and the only definite treatment is surgical resection.

Case report

A 45-year-old man presented with a 2-week history of worsening, non-specific, abdominal pain. Two years before, he had a grade II astrocytoma debulked. He was given steroids postoperatively and developed steroid-induced pancreatitis, which was severe enough to require an intensive-care admission. He had another debulking of the tumour a year later and, unusually, the histology was the same and had not progressed.

On admission, his baseline observations were normal, except a mild tachycardia. Abdominal examination revealed two 10-cm masses in his lower abdomen that were mildly tender. His C-reactive protein was significantly raised (270 mg/l), his white cell count was mildly elevated (11.8 × 10⁹/l), but the rest of the blood tests were normal. A CT-scan was performed and showed two abdominal masses of indeterminable cause.

After a day in hospital, his abdominal pain worsened and he became peritonitic on clinical examination. An emergency, exploratory, laparotomy was performed. A mass measuring 8 cm by 10 cm was found in the terminal ileum, together with a large haematoma in the left colonic mesentery: 28 cm of small bowel was excised, and the haematoma removed. Histology showed a benign mesenteric fibromatosis. The architecture was mostly composed of spindle cells, but there were also areas with dense strands of collagen similar to what is seen in keloid scars (Fig. 1). The patient recovered well and was discharged after a week. At a 3-month follow-up appointment, no further problems were reported.

Figure 1.

Mesenteric fibromatosis, showing keloidal-like features.

Discussion

Fibromatosis (also known as desmoid) is a benign tumour that occurs most commonly in the abdominal wall or extremities. Very rarely, as in this case, it can occur from the mesentery. In many cases the tumours are related to Gardner's syndrome;¹ when they are not, they most commonly occur in young women during or after pregnancy. The aetiology is unknown but an endocrine cause is suggested by: (i) the relative prevalence in perinatal women; (ii) tumour regression after the menopause; and (iii) regression with tamoxifen therapy.

Mesenteric fibromatosis is sufficiently rare for no clear data of incidence and presented features to be known. Case reports show that it can present as pyrexia of unknown origin (with a raised C-reactive protein),² ileus,³ and as a mass.¹ There are no reports in the literature of acute abdominal pain as the presenting feature. An interesting feature in this case was the association with astrocytoma. There are no reported cases of mesenteric fibromatosis, or associated tumours, having any relation to astrocytoma. One case report⁴ describes an intra-abdominal lymphoma (which presented with acute abdominal pain, as in our case) being associated with astrocytoma in a young male with the p53 gene mutation (Li-Fraumeni syndrome). However, in our case report, the association is almost certainly a co-incidence. Of note, the C-reactive protein was significantly elevated and this may have been induced by inflammatory factors produced by the tumour, such as those produced in inflammatory fibrous histiocytoma.²

The management of mesenteric fibromatosis can be difficult. Although they are benign, they can become large and so there is a significant morbidity associated with surgical resection; however, there is no other definitive treatment available. One study⁵ showed no survival difference between resected and unresected patients, noting that some tumours have prolonged periods of stability or even regression. As imaging cannot give a definite diagnosis, an operation will always be required to establish the histology; this could just be a laparoscopic biopsy, full resection being reserved for symptomatic control.

Our case illustrates another possible cause of acute abdominal pain. Although rare, mesenteric fibromatosis should form part of the list of differentials for abdominal masses and pain, particularly in the presence of a raised C-reactive protein. Once the diagnosis has been made, the only current treatment option is surgical resection.