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Mesenteric desmoid tumordeveloping on the site of an excised gastrointestinalstromal tumorMohammad Khan,1 George Bozas,1Justin Cooke,2 Kevin Wedgwood,3Anthony Maraveyas1

1Academic Department of Oncology,Queen’s Cancer Centre, Castle HillHospital, Cottingham, UK;2Department of Pathology, Hull and EastYorkshire Hospitals NHS Trust, Hull, UK;3Department of Surgery, Hull and EastYorkshire Hospitals NHS Trust, Castle HillHospital, Cottingham, UK

Abstract

We present a case of a rare and unusualoccurrence of a desmoid tumor at the site of aresected gastrointestinal stromal tumor andmimicking a recurrence, with a brief discus-sion of the management of desmoid tumors.

Introduction

Desmoid tumors, also known as deep oraggressive fibromatoses, are rare with anannual incidence of two to four cases per mil-lion.1 The term desmoid, coined by Muller in1838, is derived from the Greek word desmos,which means tendon-like.2 They represent low-grade mesenchymal neoplasms, originatingfrom musculo-aponeurotic stromal elements.They do not metastasize but tend to exhibit ahigh degree of local infiltration and invasion,thus becoming lethal in some cases, depend-ing on their anatomical localization.3 Desmoidtumor development has been associated withgenetic predisposition in patients with familialadenomatous polyposis (FAP)4 and previoustrauma of the area.5,6 Dysregulation of the Wntsignaling pathway, which is involved in thepathogenesis of FAP and also in the process ofwound healing, may be a critical underlyingmolecular mechanism in FAP-associated casesand possibly in sporadic ones as well.7 In onethird of sporadic cases, chromosomal changessuch as trisomy-20 or -8 have been identified.8

An association with the female gender andpregnancy9 suggests a pathogenetic role forestrogenic influence; nevertheless, relativedata are observational. We report here a rare and unusual case of

desmoid tumor developing at the site of a gastrointestinal stromal tumor (GIST) resec-

tion. This created the impression of GISTrecurrence. Surgical excision of the lesion wasa difficult decision owing to the suspicion ofmetastatic disease. We present a discussion onthe basis of this case for the management ofboth desmoid tumors and GIST.

Case Report

A 37-year-old IT engineer with an otherwiseunremarkable medical history was admitted tothe acute assessment unit with acute uppergastrointestinal bleeding. An ultrasound scanof the abdomen performed as part of the work-up for this condition revealed a large gastricmass and liver lesions consistent with metas-tases. Contrast-enhanced computed tomog -raphy (CT) of the abdomen showed a 15 cmexophytic mass originating from the gastricwall (Figure 1A) and four enhancing liverlesions of 19 mm maximum diameter (Figure1C). Endoscopy revealed a single gastric fundalmass with a large ulcer that was biopsied.Histological diagnosis was of a GIST, stainingpositively for C-KIT and CD34 and with a highmitotic rate. PET imaging showed a markedlyincreased uptake in the gastric mass (SUV15). The larger of the imaged liver lesions didnot show any significant FDG uptake while thesmaller lesions were not assessable.Treatment with imatinib mesylate (400 mg

daily) was initiated, and the first assessmentCT scan performed three months later showeda partial response of the gastric tumor (Figure1B), according to the RECIST (ResponseEvaluation Criteria in Solid Tumors) criteria.10

In addition, the liver lesions were reduced insize uniformly. This treatment was continuedand further scans over the next five monthsshowed stable disease. Subsequent scans weredone as magnetic resonance imaging (MRI) toassess the extent of the hepatic lesions, fromwhich it was concluded that they were notmetastatic in nature. In light of a goodresponse to treatment the patient underwent atotal abdominal gastrectomy. The procedureachieved excision of the tumor together withan intraoperatively detected omental second-ary lesion (Figures 1C). Pathological findingsreported positive margins (microscopic-R1resection) at the splenic and pancreaticaspects. Imatinib was continued postoperative-ly. Plans for surgical removal of the liverlesions were abandoned when the MRI scan ofthe liver revealed multiple nonspecific tinylesions widespread throughout the liverparenchyma.The patient remained asymptomatic and

well on imatinib treatment for another 11months, when a repeat MRI scan of theabdomen revealed a new mesenteric mass 3cm in diameter (Figure 1D), while the appear-

ance of the liver lesions remained unchanged.A multidisciplinary team meeting decision wasmade to resect the lesion surgically. Theexcised lesion represented a firm nodularmass with a thin connective tissue capsule,measuring 6.0¥4.0¥4.5 cm (Figure 2). Amesenteric and an anterior abdominal wallnodule were also removed. Microscopically thelarger mass appeared as a circumcised unen-capsulated tumor of varying cellularity. Towardthe periphery it was composed of spindle cellswith elongated nuclei and a small amount ofpale eosinophilic cytoplasm arranged betweenbroad sweeping fascicles (Figure 3A). Nonuclear atypia was noted. Toward the center ofthe lesion there was pronounced keloidal colla-gen deposition (Figure 3B). The tumor showedweak staining for desmin and was negative forCD34 and C-KIT. The pattern was typical of anintra-abdominal desmoid tumor. The other twonodules turned out to be a mesenteric lymphnode with sinus histiocytosis and a pseudo-cyst with no evidence of malignancy. Thepatient continued on imatinib (400 mg OD)treatment and follow-up MRI scans did notshow any recurrence of the desmoid tumorover the next eight months.

Discussion

Desmoid tumors usually manifest as slow-growing, deep-seated, painless or slightlypainful masses and can develop at virtually anyanatomical site.11 Typically three localizationsare described: trunk/extremity, abdominal wall,and intra-abdominal region. Usually FAP-asso-ciated cases occur in the abdomen, while non-FAP-associated cases present in the shoulderor hip regions and in the extremities.5 Theycan be multifocal on an extremity, but differentanatomical regions rarely are affected in thesame patient. Inside the abdomen they can

Rare Tumors 2010; volume 2:e33

Correspondence: Mohammad Muneeb Khan,Queen’s Cancer Centre, Castle Hill Hospital,Castle Road, Cottingham, HU16 5JQ, UK.E-mail: mmkhan_261@yahoo.com

Key words: mesenteric desmoid tumor, gastro -intestinal stromal tumor.

Received for publication: 27 September 2009.Revision received: 23 March 2010.Accepted for publication: 25 March 2010.

This work is licensed under a Creative CommonsAttribution 3.0 License (by-nc 3.0).

©Copyright M. Khan et al., 2010Licensee PAGEPress, ItalyRare Tumors 2010; 2:e33doi:10.4081/rt.2010.e33

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cause changes in bowel habits, pain, obstruc-tion, ischemia, rectal bleeding, or a dysfunc-tional anastomosis, and are a significant causeof mortality for FAP patients. Non-intra-abdom-inal desmoids have a better prognosis.7,12

Complete surgical resection remains thecornerstone of management of desmoidtumors, while unresectable or residual diseasecan be treated with radical radiotherapy.11

Depending on tumor size, type of treatment,and negative margins post-resection, recur-rences occur in up to 45% of treated adultcases, usually within three years from diagno-sis.13 Systemic treatments with NSAIDs, anti -

estrogens or androgens, chemotherapy (dox-orubicin-based, methotrexate, vinblastine,vinorelbine), and lately imatinib have beenused for unresectable or relapsed desmoids,often resulting in long-lasting responses.14 Inselected asymptomatic patients, a period ofwatchful waiting is recommended.15

Prior trauma is identified in 30% of patientswho develop desmoid tumors, and is typicallyabdominal surgery for FAP.4 In addition, spor -adic cases of intra-abdominal desmoid tumorshave been observed in sites of previous abdom-inal surgery.12,16,17 Our literature search yieldedone previous report of a desmoid tumor arisingin the site of a previously excised GIST.18 GISTsand desmoid tumors share a common stromalorigin but are diverse histologically, genetical-ly, and biologically. Nevertheless, surgical trau-ma at the GIST excision site may predispose tothe development of the desmoid tumor. Anaccurate diagnosis is possible only after surgi-cal removal and pathological exam ination, asthere are no typical imaging findings to sug-gest a desmoid tumor. Excluding recurrence ofthe GIST was crucial for the further manage-ment of our patient; he remained on imatinibfor the metastatic GIST; therefore he contin-ued to benefit from first-line treatment andremains progression-free after eight months.

References

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Case Report

Figure 1. A contrast-enhanced computed tomography scan of the abdomen showing: a15-cm exophytic mass originating from the gastric wall (arrow) (A); and four enhancingliver lesions of maximal diameter of 19 mm (C). A three-month follow-up abdominal CTscan (B) demonstrated a partial response to treatment of the gastric tumor (arrow). Arepeat MRI scan of the abdomen after 11 months revealed a secondary mesenteric omen-tal mass, 3 cm in diameter (D).

Figure 2. Macroscopic view of the second-ary mesenteric lesion, showing it as a firmnodular mass with a thin connective tissuecapsule, measuring 6.0¥4.0¥4.5 cm.

Figure 3. A histological section of the larg-er mass illustrating: (A) toward the periph-ery of the tumor, spindle cells with elongat-ed nuclei and a small amount of paleeosinophilic cytoplasm, and (B) pro-nounced keloidal collagen depositiontoward the center of the lesion. No nuclearatypia was noted. (Hematoxylin and eosinstain; magnification 100X).

A

B

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Case Report