Caecal desmoid tumour: a rare tumour at uncommon location and review of literature

Abstract

A 49-year-old woman presented to surgery outpatient clinic with the awareness of a right lower abdomen asymptomatic lump for one week. Contrast-enhanced CT of the abdomen demonstrated a 10×11×15 cm heterogeneous lesion anterior to the ileocecal junction with the possibility of leiomyosarcoma. The patient was prepared for laparotomy and intraoperative there was a large tumour arising from the medial wall of cecum. Right haemicolectomy was performed, and histopathology came as a desmoid tumour of the cecum. The patient had an uneventful postoperative course and is well on 1-year follow-up.

Background

Desmoid tumour (DT) is a benign tumour, and it arises from musculoaponeurotic structures with an estimated incidence of 0.03% of all malignancies and less than 3% of all soft tissue tumours.¹ Only about 12%–18% of DTs are intra-abdominal, and they commonly arise from the mesentery.² Although benign it is a slow-growing locally aggressive tumour with no metastatic potential. DT arising from the caecum is a very rare presentation. There is one case report cecal fibromatosis mimicking periappendicular abscess.³ Herein, we report a case of a 49-year-old woman who presented with an asymptomatic abdominal lump mimicking gastrointestinal stromal tumour on imaging and was managed surgically by en bloc excision. The final diagnosis of histopathology came as a caecal DT.

Case presentation

A 49-year-old woman with no known comorbidities presented to surgery outpatient clinic with an awareness of lump in the right lower abdomen for 1 week. The lump was not associated with pain or symptoms suggestive of intestinal obstruction or gastrointestinal bleed. She had normal appetite and no history of weight loss or recent change in bowel habits. She was an averagely built and nourished woman. Her general physical examination was unremarkable. On per abdominal examination, there was a 10×10 cm well-defined firm mass in right iliac fossa with a smooth surface and with limited mobility both in the transverse and longitudinal plane. Colonoscopy and blood investigations, including carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) were normal. On Contrast-enhanced CT (CECT) of the abdomen, there was a 10×11×15 cm homogeneous mass lesion with mild enhancement anterior to ileocecal junction (ICJ) (figure 1). Cecum was not seen distinctly, and the appendix was normal. A provisional diagnosis of a caecal mass likely leiomyosarcoma was made.

Figure 1.

(A) Coronal image showing a well-defined homogeneously enhancing soft-tissue lesion in the right lumbar region, the caecum is not seen separately from the lesion suggesting the likely origin. (B) Axial image depicting the lesion with displacement of the ileal loops.

The patient was prepared for surgery, and on exploration, there was about 17×10 cm tumour arising from the medial wall of the caecum and adjoining mesentery (figure 2). Liver, small and large bowel, appendix, peritoneum and ovaries were normal. Right haemicolectomy with ileocolic anastomosis was performed. On gross examination, the caecum on its serosal aspect showed a large encapsulated mass measuring 16.5×12×9 cm. There was a solid, homogeneous, shiny, mucinous tumour with fibrous streaks with no definite areas of necrosis on cut section. Tumour was strictly restricted to submucosa grossly with no capsular breach. Microscopic examination revealed a tumour from the serosal aspect, composed of spindle cells arranged in interlacing fascicles. The tumour cells had a bland nuclear morphology with wavy to oval nucleoli and moderate eosinophilic cytoplasm, with no mitosis (figure 3). On immunohistochemistry, beta-catenin positivity and negative staining for c-kit and DOG-1 helped clinching the diagnosis of a DT.

Figure 2.

Intraoperative view: (A) A desmoid tumour (DT) arising from the medial wall of the caecum (C). (B) Right haemicolectomy specimen. a, appendix; AC, ascending colon; C, caecum.

Figure 3.

Tumour composed of spindle cells arranged in interlacing fascicles (A) H&E stain, magnification ×100; (B) H&E stain, magnification ×400), Immunohistochemistry reveals tumour cells show nuclear positive (C) immunoperoxidase stain, magnification ×400) and cytoplasmic positivity (D) immunoperoxidase stain, magnification ×400) for beta-catenin.

The postoperative course was uneventful and patient was discharged on postoperative day 7 in a stable condition. She is well after 1 year of surgery without any evidence of clinical or radiological recurrence.

Outcome and follow-up

At 6 months postright haemicolectomy for caecal DT, the patient was doing well. Patients under regular follow-up, planning for colonoscopy after 1 year.

Discussion

DTs are sporadic (80%), and only 20% are associated with familial adenomatous polyposis syndrome or Gardner syndrome.¹ They may be associated with trauma, pregnancy and use of oral contraceptive pills; and can present at any age but more commonly seen between 25 and 35 years with a slight female preponderance.⁴ As intra-abdominal DTs are slow-growing and locally infiltrative; the patient may be asymptomatic, to begin with and diagnosed incidentally on imaging performed otherwise. When they attain a large size or because of inherent infiltrative nature they may cause obstructive or compressive symptoms; and present with vague abdominal complaints, abdominal pain or lump, intestinal obstruction or perforation and bleeding secondary to compromise of blood supply and submucosal ischaemia. They may also present with compression of ureter causing hydroureteronephrosis and splenic vein compression leading to portal hypertension.³

Diagnosis of intra-abdominal DTs is tough due to its rarity and resemblance to other mesenchymal tumours. CECT abdomen aids in defining tumour size, location, invasion of adjacent structures and resectability. Most DTs on CECT scan appear as well defined or poorly defined homogeneous tumour which may be iso or hyperdense compared with muscle.⁵

Mesenteric tumours may have strands radiating into adjacent fat or as a whorled appearance of fibrosis. MRI is another modality to diagnose DTs. MRI characteristics of DTs depend on the histological component of the tumour. A fibrotic and collagenous portion of DT has shown low signal intensity on T2-weighted images and mild enhancement on the delayed phase of post contrast images; cellular stroma and myxoid matrix manifest as hyperintense areas on T2 images. Presence of T1 and T2 hypointense bands are seen within the tumour is reported to be a characteristic MRI finding of DTs (band sign), and is present in about 60%–90% of DTs.⁶

The role of fluorodeoxyglucose-positron emission tomography (FDG-PET is not fully defined for diagnosis and treatment, but can be used to estimate the response to chemotherapy.⁷ On histopathological examination, these are characterised by proliferative spindle cells in the background of abundant collagen.⁸

Mesenteric desmoid has large amount of myxoid stroma compare to intrabdominal DTs. Typical morphological features of DT include the presence of proliferative, involutional and residual phase simultaneously with positive staining for nuclear b-catenin, vimentin and smooth muscle actin. They rarely stain positive for cyclooxygenase 2, tyrosine kinase, androgen and oestrogen receptors but are always negative for desmin, S-100, CD34 and c-KIT.⁹

As most of these tumours occur sporadically, these tumours must be identified and operated owing to their locally aggressive nature and potential complications of perforation, obstruction and abscess formation. Delay in surgery may lead to need for more radical procedures due to extensive infiltration and increased morbidity to the patient. There are no definite guidelines available for the management of DTs. However, asymptomatic patients in the absence of biological prognostic factors (initial tumour size, growth rate) which are capable of predicting the natural history of the disease, watchful waiting is a reasonable approach to minimise overtreatment and unnecessary morbidity in a subset of patients.¹⁰ Also, in familial cases, the patient should be kept under a follow-up and to be operated only if indicated as in these cases recurrence rate up to 75% has been reported after surgery.¹¹ Surgery aims at complete resection of the tumour so as to achieve negative margins. Patients with involved resection margins experience recurrence within 15–24 months.¹² Therefore, adjuvant treatment should be given in cases of incomplete resection. When the tumour is locally advanced involving vital structures and surgery is not feasible, options of radiotherapy, chemotherapy and systemic hormone therapy should be considered. Thus, a stepwise multidisciplinary approach with the involvement of medical oncologist may lead to a better outcome. Systemic treatment includes non-steroidal anti-inflammatory drugs (sulindac and celecoxib), tamoxifen (suppresses DT growth due to the presence of oestrogen receptor on tumour cells), tyrosine kinase inhibitors (imatinib, sunitinib, sorafenib) and chemotherapy (doxorubicin and methotrexate with vinca alkaloids) which can be used as adjuvant or neoadjuvant treatment with or without radiotherapy.^{13 14}

The patient should be followed up regularly to detect early recurrence or relapse even after achieving R-0 resection. NCCN guidelines recommend 3–6 monthly follow-up for 2–3 years and annually thereafter.¹⁵

Conclusion

DTs are rare and locally aggressive with a variable clinical presentation. Therefore, a high level of clinical suspicion is required for its diagnosis. Resection with negative margin is the gold standard treatment for sporadic tumours. However, radiation and systemic treatment may be required in cases of residual tumour or recurrence.

Learning points.

• Intrabdominal desmoid tumours are rare and characterised by infiltrative nature; however, they never have metastasis.

• Majority (80%) are sporadic, and only 20% have an association with familial adenomatous polyposis.

• Commonly these tumours are asymptomatic; however, they can present with complication because of its infiltrative nature.

• En bloc resection with negative margins offers excellent prognosis.

• A multidisciplinary approach is required in patients with familial lesions, inoperable tumour or in patients with negative margins in view of high recurrence.