Discussion:
fibromatoses (Desmoid-type) tumour is rare benign fibrous tumours account approximately for 0.03% of all neoplasms in USA. Pancreas is even more rarely reported subset with approximately 5% of all desmoid-type fibromatoses [8–10].
The unique aggressive local invasion is characteristic of DT that render the tumour unresectacble or with high local recurrence, but not unknown to case distant metastases as thesis a benign tumour.
These tumours are more commonly present in young adolescent patient [5, 11]. intraabdominally DT, occurs in around 8% of all DT and more likely to be in adults than paediatric age groups, affecting any part of the gastrointestinal and genitourinary tracts [12] the comments origin of intraabdominal DT are of mesenteric or retro peritoneum connective tissue. the pancreatic origin DT remain an extremely rare subset of DTs. The English literature from the 1980s report 27 pancreatic DT, therefor our case is the 28th case [1, 2, 4, 5, 10, 13–18].
clinical presentation of intraabdominal DTs is none specific in symptoms and signs. In general symptoms and signs are related anatomical location of the DT mass and/ or invasion of nearby structures causing bowel obstruction, ischemia, fistulas, gastrointestinal bleeding or perforation an ureteric obstruction. Pancreatic-origin DT behave like pancreatic cancer in presentation as asymptomatic mass or with nonspecific mild epigastric pain or painless jaundice if the tumor location is in the head or the uncinate process. [1, 5]. Our patient presented with mild to moderated abdominal pain associated with nausea, weight loss and splenic mass for investigation. and possible complications [19].
Imagining is valuable especially CT scans and/ or MRI to determine invasiveness, aid in biopsy approach and to assess resectability but not diagnostic [1, 4, 5].
In FNA histopathology as in our case the presence of spindle cells is common but not pathognomonic for DT. The Immunohistochemistry feature of intraabdominal DT characterize by a positive vimentin and β-catenin and as importantly negative for S100, CD34, and CD117 for the SMA [5]. Our case confirmed typical DT Immunohistochemistry criteria (Fig 3).
the immunohistochemistry is the mainstay of confirming DT with characteristic negative S100 protein, in most of the case with rare exceptions [20]. the presence of positive nuclear β-catenin staining is important diagnostic feature present in around 80% of the cases but not specific only for this tumour.
Unequally DT can be further confirmed by demonstrating mutations of β-catenin gene in exon 3 which is positive in 85% of the case [11,13].
Favourable prognosis reported by Jia et al. with overall survival of 100% and disease-free survival of more than 80% [5]. however, accurate prognosis is not well reported and in sporadic cases reported high postoperative recurrence rate around 19-77%, especially when associated with Gardner syndrome and FAP with recurrence rate up to 90% [5, 16].
To date there we lack consensus or guidelines for management of DT. The first-line management of DT was and remain wide free margin complete resection (radical resection) given the aggressive nature and excessive local invasive behaviour of the tumour with the guidance of frozen section support considering the locally invasive behaviour of this tumour. Observation without surgical resection also called wait-and-see approach mainly in static tumour were recommended by some expert to avid morbidity and the possible high recurrence associated with surgery especially in asymptomatic cases with mild manageable symptoms.
As a possible second line of management and specifically in case of high-risk patients for surgical intervention or in advance stages an adjuvant systemic chemotherapy based mostly in combination of methotrexate, vinblastine, doxorubicin, and dacarbazine and /or radio- or molecular target therapy as Tamoxifen. The use of COX2 inhibitors e.g., NSAID and celecoxib demonstrated promising successes in some studies, however, the mechanism by which it achieves regression is not clearly reported [4, 5, 16, 19].