Aims:

Desmoid-type fibromatosis is a rare monoclonal, fibroblastic proliferation characterised by a variable and unpredictable clinical course. Surgery remains the treatment of reference but local relapses are common. Intra-abdominal desmoid tumours are often surgically challenging due to involvement of mesentery, encasement of vessels and visceral organs. Systemic treatment options include tamoxifen, nonsteroidal anti-inflammatory drugs and Imatinib, a selective tyrosine kinase inhibitor with reported objective response rates of only 6%. We present a case of a 28 years old gentleman who was diagnosed with a large inoperable mesenteric desmoid tumour who has excellent response to second line treatment with Imatinib.

Methods:

Patient presented with cachexia and increased abdominal pain over several months in May 2014. Biopsy of intra-abdominal mass confirmed mesenteric fibromatosis. Mutational analysis was negative for KIT and PDGFRα mutation. There were no reported familial hereditary syndromes.  As he was deemed inoperable due to size and high vascularity of lesion, he was commenced on systemic therapy with Tamoxifen and Sulindac. This was poorly tolerated with evidence of disease progression. He received second line treatment with Imatinib in December 2014 with significant clinical and radiological response.

Results:

Initial computed tomographic (CT) scan in May 2014 revealed a large, solid hypervascular mass in the abdomen arising from the mesentery measuring 23x12x21cm. Following commencement of Imatinib in Dec 2014, there has been an extraordinary reduction in tumour bulk from 30x17x30cm  to  8.7x5.2cm over 6 months period and can now be considered for curative surgical resection.

Conclusions:

Imatinib should still be considered in patients with refractory desmoid tumours, regardless of their receptor tyrosine kinases mutation status. Further studies should be considered to assess long term efficacy of Imatinib and sequencing in the treatment paradigm of desmoid tumours.