Primary intramural fibromatosis of the small bowel: An uncommon cause of intestinal obstruction

Maggie J Lin; Richard P Sharpe; Stanislaw P Stawicki; Santo Longo; Lisa Stoll

doi:10.4103/2455-5568.222474

CASE REPORT

Year : 2017 | Volume : 3 | Issue : 2 | Page : 280-284

Primary intramural fibromatosis of the small bowel: An uncommon cause of intestinal obstruction

Maggie J Lin¹, Richard P Sharpe¹, Stanislaw P Stawicki², Santo Longo³, Lisa Stoll³
¹ Department of Surgery, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA
² Department of Research and Innovation, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA
³ Department of Pathology, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA

Date of Web Publication

9-Jan-2018

Correspondence Address:
Dr. Stanislaw P Stawicki
Department of Research and Innovation, St. Luke's University Health Network, EW2 Research Administration, 801 Ostrum Street, Bethlehem, Pennsylvania 18015
USA

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/2455-5568.222474

Abstract

Small bowel obstruction is a commonly encountered surgical diagnosis, most frequently attributed to hernias, adhesions, or malignancy. Intra-abdominal fibromatoses are rare tumors with heterogeneous clinical manifestations. Infrequently, acute presentation of bowel obstruction may be associated with intra-abdominal fibromatosis – also referred to as “desmoid tumor” – a benign proliferation of myofibroblasts which most often arise from the mesentery or retroperitoneum and are nonmalignant in character. Here, we describe a case of an isolated abdominal fibromatosis with primary involvement of the intestinal wall and the clinical presentation of bowel obstruction. The patient was managed by surgical resection and had complete recovery. As demonstrated in the current case, physically small, relatively isolated desmoid tumors have the potential to significantly impact the patient. Individualized treatment approaches produce good clinical outcomes in most cases.
The following core competencies are addressed in this article: Medical knowledge, Patient care.

Keywords: Desmoid tumor, primary intramural fibromatosis, small bowel obstruction

How to cite this article:
Lin MJ, Sharpe RP, Stawicki SP, Longo S, Stoll L. Primary intramural fibromatosis of the small bowel: An uncommon cause of intestinal obstruction. Int J Acad Med 2017;3:280-4

How to cite this URL:
Lin MJ, Sharpe RP, Stawicki SP, Longo S, Stoll L. Primary intramural fibromatosis of the small bowel: An uncommon cause of intestinal obstruction. Int J Acad Med [serial online] 2017 [cited 2020 Dec 3];3:280-4. Available from: https://www.ijam-web.org/text.asp?2017/3/2/280/222474

Introduction

Small bowel obstruction is a commonly encountered surgical diagnosis, most frequently attributed to hernias, adhesions, or malignancy.^[1] Among less common causes is intra-abdominal fibromatosis, also referred to as “desmoid tumor,” a benign proliferation of myofibroblasts which typically arise from the mesentery and retroperitoneum. These lesions have a propensity to involve bowel and have no malignant potential.^[2],[3] Although majority of reported cases are spontaneous in character, some occurrences may present in the setting of Gardner's syndrome or familial adenomatous polyposis.^[3] Other associated diagnostic entities include trauma, surgical scars, and high estrogen states.^[4] Desmoids can also mimic gastrointestinal stromal tumors (GIST), particularly in elderly patients.^[5] Here, we present a case of high-grade small bowel obstruction secondary to a primary intramural small bowel fibromatosis.

Case Report

A 67-year-old female with past surgical history of gallstone pancreatitis and laparoscopic cholecystectomy several years ago presented with a 6-month history of vague abdominal pain, nausea, and irregular bowel movements. Her symptoms worsened significantly several days prior to the current evaluation.

The patient had a negative esophagogastroduodenoscopy and colonoscopy during the preceding year to investigate her abdominal symptoms. Physical examination findings included mild abdominal distention and vague generalized tenderness. Her vital signs were normal and laboratory studies were unremarkable. Computed tomography (CT) scan of the abdomen demonstrated a segment of abnormal small bowel in the left mid-abdomen, with associated high-grade obstruction [Figure 1]. A nasogastric tube was placed, with large amount of immediate bilious output. A subsequent small bowel follow through contrast study demonstrated a near-obstructing intramural lesion in the area of distal jejunum or proximal ileum [Figure 2]. Given evidence of an “obstructing mass,” we proceeded to the operating room for an exploratory laparotomy with the intent to resect the involved bowel.

Figure 1: Contrast-enhanced computed tomography scan showing a high-grade bowel obstruction in the mid-abdomen

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Figure 2: Small bowel follow through examination showing a near-obstructing intraluminal lesion in the small intestine

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During laparotomy, a hard, tan-pink mass was found in the distal jejunum. It was approximately 4 cm in size, encompassing the circumference of the involved small bowel segment. There was an associated dilated proximal bowel and clearly decompressed distal bowel. The specimen removed included a segment of jejunum spanning between approximately 10 cm proximal and 10 cm distal to the area of obstruction. The resection also included the corresponding blood supply, down to the root of the mesentery [Figure 3].

Figure 3: An intraoperative photograph showing solid mass encasing the bowel wall, with involvement of the mesentery

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A hand-sewn, two-layer small bowel anastomosis was performed and the mesenteric defect closed. The patient's postoperative course was uneventful. She was discharged on the 6^th postoperative day after the return of bowel function and resumption of regular diet. She was doing well at the 1-year follow-up visit, and her initial abdominal symptoms had completely resolved. A 25 cm × 4 cm segment of small intestine was submitted for pathologic examination. In the center of the specimen, a 5–6 cm externally palpable mass was covered by intact serosa and abutted on grossly normal appearing mesentery. On sectioning, constrictions of the bowel wall were present around a 3.7 cm × 2.6 cm × 2.4 cm intramural tumor. The entire periphery of the mass was sharply defined. Its cut surface was tan-pink, whorled, and rubbery. Microscopically, a benign fibromatosis formed the entire mass. This histological picture is akin to benign desmoid tumors, which have been well defined in the gastrointestinal tract.^[5],[6] There were no histological features of dysplasia or malignancy. The fibrocystic origin of the excised lesion was confirmed by subsequent histology and immunohistochemistry determinations. The tumor cells were positive for beta-catenin [Figure 4], smooth muscle actin (SMA), vimentin, and negative for CD117, CD34, and “discovered on GIST,” which are positive in other tumors. The lesion did not directly involve the mesenteric fat but extended to the radial serosal surface, which is not a true resection margin. All true surgical margins were negative for tumor. See [Figure 5] and [Figure 6] for additional histological characteristics of the resected lesion.

Figure 4: Up-regulated production of beta-catenin protein demonstrated by prominent intranuclear accumulation of protein on the anti-beta-catenin stain (×400)

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Figure 5: Finely fibrillar pink collagen containing numerous translucent light blue, slender fusiform nuclei on (H and E, ×100)

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Figure 6: Nuclei containing a single central nucleolus with very rare mitoses, devoid of atypia, or pleomorphism on (H and E, ×400)

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Discussion

Although small bowel obstruction has an extensive list of potential causes, it is rarely described as a consequence of intra-abdominal fibromatosis. Even more unusual is fibromatosis arising primarily within the intestinal wall. The list of diagnoses that may overlap in clinical presentation with intra-abdominal fibromatosis includes sclerosing mesenteritis, lymphoma, carcinoid tumor, carcinomatosis, and primary mesenteric mesothelioma.^[7] The pathogenesis of intra-abdominal fibromatosis is not well understood. Patients usually are asymptomatic but may develop a bowel obstruction. Less commonly, presentation may include gastrointestinal bleeding, fistula formation, or bowel perforation.^[4],[8] The majority of intra-abdominal fibromatoses arise from the mesentery or retroperitoneum with frequent involvement of the small bowel wall. Although benign, these lesions have a high rate of recurrence and local extension.^[8] Abdominal fibromatosis may be more likely to affect young adult females between the ages of 20–30 years.^[9]

It has been suggested that contrast-enhanced CT and magnetic resonance imaging (MRI) may offer some correlation with histological findings, but there are no specific radiologic features to diagnose fibromatosis.^[10] Desmoid tumors typically appear as well-circumscribed masses with features corresponding to mesenteric fat and vessels on both ultrasound and CT.^[2] On CT and MRI, desmoid tumor typically appears as a soft tissue mass displacing surrounding structures, with increased collagen content and vascularity.^[11] However, desmoids can resemble other solid tumors, making specific radiologic diagnosis difficult.^[8],[10] Still, some CT criteria suggestive of intra-abdominal fibromatosis have been described, including ovoid or irregular contour, homogenous enhancement, absence of intralesional necrosis, and a degree of enhancement <40.5 Hounsfield units (HUs) in the arterial phase versus 46.5 HU in the portal venous phase.^[12]

On pathologic evaluation, desmoid tumors appear as homogenous proliferations of wavy spindle cells without atypia or necrosis, separated by large amounts of collagen and dilated thin-walled vessels in a parallel pattern.^[13] The lack of mitotic activity and pleomorphism characterizes fibromatosis. Grossly, these tumors appear firm, large, and poorly defined.^[8] All of these characteristics were present in our patient's resected specimen. Distinguishing intra-abdominal fibromatosis from GIST and malignancies such as sarcomas is critical so that treatment can be directed appropriately. The clinical course and pathophysiology of GIST and fibromatosis may be difficult to differentiate once there is involvement of the bowel wall.^[6] In the current case, GIST was initially suspected given the patient's age and the gross tumor characteristics. However, GIST tumors tend to be soft, “fleshy,” contain areas of necrosis/hemorrhage on cross-sectional analysis, and typically stain positive for CD117.^[14] Vimentin, SMA, and CD117 staining are found in many soft tissue tumors including desmoid tumors, but nuclear β-catenin expression and negative CD34 immunostain have been identified primarily in deep fibromatoses.^[13],[15]

Standard therapeutic approach includes wide surgical excision, with primary aim of achieving negative resection margins.^[16] Current treatment strategies are generally based on fragmentary evidence, primarily from cases and case series. Treatment modalities including radiotherapy, chemotherapy, nonsteroidal anti-inflammatory drugs, interferon, and antiestrogen agents are being investigated, but the efficacy of these alternatives continues to be poorly defined.^{[8],[17],[18]} In the setting of intra-abdominal tumors involving small bowel, radiation therapy may lead to subsequent enteritis and should be used with caution.^[19] In most instances, management is multimodal and tends to be highly individualized. In the current case, resection of involved bowel and the associated mesentery was successfully performed with negative margins. There was no indication for additional therapy and there has been no evidence of recurrence after 1 year of close follow-up. The optimal length of clinical monitoring in cases of mesenteric fibromatosis is not well defined. The threat of relapse in high-risk patients can persist for as long as 2-3 years,^[20] with some recurrences reported 3–5 years after the initial resection.^[21] In general, prognosis is good after complete excision. If local recurrences are identified, excision with curative intent is indicated whenever possible.^[17] Not unexpectedly, mortality and morbidity both increase with each subsequent operative intervention.^[22] In refractory cases, death may occur within years, and is usually associated with extensive, progressive involvement of abdominal organs.^[22]

Conclusions

Intra-abdominal fibromatoses are benign tumors with a heterogeneous spectrum of presentations. In the current case, the clinical appearance of abdominal fibromatosis mimicked that of GIST due to the primary involvement of the intestinal wall and the associated bowel obstruction. Our case demonstrates that even relatively isolated, physically small desmoid tumors can have a significant impact on the patient. If treated appropriately, good clinical outcomes can be expected.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical conduct of research

The authors attest that this scholarly work was conducted in accordance with the recommendations of The International Committee of Medical Journal Editors. Patient consent was obtained prior to the submission of this manuscript for publication in the International Journal of Academic Medicine.

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