Desmoid tumours are benign deep fibromatoses originating from fascia and muscle aponeurosis with an infiltrating growth.1 They are primarily located abdominally or intra abdominally,2 while only sporadically described within the thoracic wall3 or retroperitoneum4. The incidence of desmoid tumour is 2 to 4 per million population and of these, 8% are mesenteric.5 Desmoid tumours are the most common primary tumours of the mesentery, while majority of tumours of the mesentery represent secondary metastases from abdominal organs such as intestine or rarely from the breast and lung. The most common site for mesenteric desmoid is at the base of small bowel mesentery. Desmoids may compress or displace adjacent bowel loops or ureters leading to intestinal obstruction or hydronephrosis. Treatment modality is primarily surgical while radiotherapy, chemotherapy, anti-inflammatory treatment and hormone therapy have also been tried with variable results.

A 49 year old male presented with a six month history of lump in the central part of abdomen with mild, dull aching, continuous pain for about a week. There was no history of fever, vomiting, altered bowel or bladder habits. He also gave no history of trauma, surgery or drugs consumed in the past. On examination, there was a 10x10 cm, hard, non tender, mobile intraperitoneal lump with no organomegaly or free fluid in the abdomen. On investigation, haematological profile, laboratory values and X-rays were found to be normal. Ultrasound and CT scan showed a large solid intra abdominal mass probably arising from the mesentery with no involvement of the adjacent bowel loops. There was no evidence of ascites or lymphadenopathy while liver and spleen were normal. FNAC showed evidence of fibromatoses. An exploratory laparotomy was performed which showed a large solid mass in the mesentery near the jejunum with common blood supply, but free from the abdominal wall and bowel loops. Wide excision of the mass was performed with resection of the local loop of jejunum. Histopathology showed evidence of interwoven bundles of spindle cells with collagen with few mitoses and absence of nucleus separations indicating a mesenteric desmoid tumour with free resection margins. The patient had an uneventful postoperative course and is asymptomatic over the past 18 months.

Fig. 1 : External appearance of resected mesenteric desmoid with adjacent loop of jejunum.	Fig. 2 : Cut surface of mesenteric desmoid tumour.

Desmoid tumours are benign deep fibromatoses originating from fascia and muscle aponeurosis with an infiltrating growth.1 The term ‘desmoid’ is derived from Greek and means ‘band like appearance’. The most common primary tumours of the mesentery, desmoid tumours were first described in 1832.6 Desmoid tumours are classified as extra abdominal, intra abdominal or located in the abdominal wall. Abdominal wall desmoids are mostly located within the rectus muscle sheath with or without intra abdominal extension. Intra abdominal desmoids arise from the mesentery, retroperitoneum or pelvis. The most common site for mesenteric desmoid is at the base of small bowel mesentery.

Incidence of desmoid tumour is 2 to 4 per million population and of these, 8% are mesenteric5. There appears to be four peaks of age: 5 years (juvenile), 27 years (fertile), 44 years (middle age) and 68 years (old age). Of these the first two groups are seen predominantly in females, while the last two have an equal sex distribution.

Desmoids are often associated with female gender and estrogen is thought to act as a growth factor with endogenous estrogen levels having a close correlation with tumour growth rate, which is slowest in young girls and reaches maximum at menopause. Patients who develop desmoid are believed to have a genetic predisposition and is often seen with FAP.7 They have a disorder similar to Gardener’s syndrome with a variable autosomal dominant inheritance. Trauma, especially operative trauma may also contribute to formation of desmoid tumour, which usually develops within four years following the incident.

Fig. 3 : CT scan showing the tumour mass.

Majority of the patients present with a non-tender mass, but pain may be associated if the tumour grows into the surrounding structures. They may compress or displace adjacent bowel loops or ureters leading to intestinal obstruction or hydronephrosis. Despite their benign appearance, desmoid tumours are locally aggressive and tend to recur in 25% to 65% of cases, but without distant metastases.

On ultrasound, it is seen as a non specific hypoechogenic mass with poor enhancement, which is indistinguishable from rhabdomyosarcoma, haematoma, abscess or metastatic disease. CT and MRI are the most useful radiological investigation and they help in localizing the tumour and ruling out metastases. Histology is the only evidential method, which demonstrates long fascicles of spindle cells of variable cell density with few mitoses and absence of atypical nucleus separations. Characteristically, there is a diffuse cell infiltration of adjacent tissue structures. Immunohistochemical response for actin can be partially positive and immunohistochemical muscle cell markers delimit desmoid tumours from fibrosarcoma.8

The therapy of choice is still controversial9. Treatment is primarily surgical which aims at radical tumour resection with free margins. Radiotherapy is successful in inducing initial regression, however excision is often necessary. A significantly better local recurrence control was described with radiation and combined surgical resection in comparison to resection only.10 Anti-inflammatory treatment with sulindac, indomethacin; hormone therapy with tamoxifen and chemotherapy have also been described, but were not found to be effective. Nonsurgical treatment has an unpredictable outcome and might be considered in patients with unresectable lesions or for adjuvant treatment. Radical resection with clear margins remains the principal determinant of outcome with risk of local recurrence.