A case of desmoid tumour

Clinical History

A 30-year-old woman came to our department because of the presence of a bulge in the anterior part of the inguinal region. The mass had grown substantially in the preceding weeks, but pain was not noted.

Imaging Findings

CT showed a swelling in the left inguinal region originating from the iliopsoas muscle and involving the iliopsoas (Fig. 1) and sartorius muscles (Fig. 2).
These findings were confirmed by ultrasound. Examination of a biopsy of the lesion resulted in the diagnosis of a desmoid tumour.
As a result of tumour's evolution, a pelvi-ureteric stent was placed on the left side. In a follow-up CT the stent was clearly visible and mild dilatation of the calyco-pelvic cavity was noted due to the expansion of the tumour (Fig. 3).

Discussion

A desmoid tumour, also called aggressive fibromatosis, is a rare type of cancer that arises from fibroblasts. Usually, this lesion develops in tendons and ligaments but it can grow in virtually any part of the body. It is a rare neoplasm accounting for 3% of soft tissue tumours and 0.03% of all neoplasms. These tumours often occur in women between 30 and 40 years, but can occur in anyone at any age without significant racial or ethnic distribution [1].
The pathogenesis of desmoid tumours is unknown but some risk factors including genetic abnormalities (2% originate from an alteration of the gene APC and represent an element of Gardner's syndrome with familial adenomatous polyposis and multiple osteomas), trauma [2] and pregnancy [3] are recognised.
A desmoid tumour is characterised by invasive growth but it does not metastasise. These tumours have a tendency to recur even after (apparently) complete resection. The symptoms are highly variable and depend on the site of the tumour. When present in the limbs, a desmoid tumour may present as a painless swelling while when the tumour is inside the abdomen it can cause pain, nausea, anaemia, vomiting, diarrhoea or fever.
Complications include compression of organs like the small bowel, ureters or vessels such as the mesenteric vessels or vena cava [4].
Ultrasound is often the first method of examination for diagnosis. Also necessary for a correct diagnosis are CT, MRI and biopsy. The desmoid tumour presents as a mass with density of the parenchyma (40-60 HU) circumscribed by a pseudocapsule but with irregular margins because of its invasive nature. On CT it appears hypodense because of its fibrous origin and after injection of contrast agents they present a high contrast enhancement during the interstitial phase. In MRI it presents hypointense in T1-T2 wt sequences [7]. CT or MRI is used also to determine whether it adheres to any nearby structure. The treatment of desmoid tumours is extremely difficult: complete resection is usually the first choice of therapy for this type of tumours but for patients who cannot have surgery radiation therapy is an effective option. Radiation can be used also as an adjunct to surgery or chemotherapy [5]. In the case of unresectable or recurrent lesions, additional treatments options (which are at best modestly effective), may be considered, including hormone therapy, chemotherapy, immunotherapy and anti-inflammatory therapy [6].

Differential Diagnosis List

Final Diagnosis

Desmoid tumour

URL:	https://eurorad.org/case/10898
DOI:	10.1594/EURORAD/CASE.10898
ISSN:	1563-4086