Small Bowel Intussusception Secondary to Metastatic Spindle Cell Sarcoma: A Case Report and Review of the Literature

Intussusception of the small or large intestine is defined
by the telescoping of a segment of bowel on itself.


Introduction
Intussusception of the small or large intestine is defined by the telescoping of a segment of bowel on itself, with the "donor" invaginated segment termed "intussusceptum" and the "recipient" segment termed "intussuscipien" [1]. The majority of intussusception is associated with a lead point from which the telescoping begins, such as enlarged mesenteric lymph nodes or tumor. While intussusception is a common phenomenon in the pediatric population and most often of benign etiology, its occurrence in the adult may be the first sign of malignancy and warrants further investigation [1][2][3]. Here we describe a 270 case of a recurrent spindle cell sarcoma with metastases to the gastrointestinal tract, resulting in jejunal intussusception 3 years after initial treatment of the primary lesion. A 50-year-old man presented to the Emergency Department with acute-onset severe left-sided abdominal pain and associated bloating. On examination, his abdomen was moderately distended and tender to palpation in the setting of normal vital signs. The patient's past medical history was significant for spindle cell sarcoma of the frontal scalp diagnosed and excised three years prior.

Case Presentation
Pathology of the excised scalp mass was consistent with high-grade spindle cell sarcoma with a high mitotic rate and tumor extension to <1mm from the surgical margin. The patient thus underwent re-resection of the close margin followed by adjuvant radiation therapy. Two years later, the patient was noted to have a progressive growth around the surgical scar. Excisional biopsy confirmed recurrent spindle cell sarcoma with positive margins. Subsequent re-excision was performed without further adjuvant treatment. In the Emergency Department, a complete blood count and metabolic panel were normal. A computed tomography (CT) of the chest, abdomen, and pelvis with contrast revealed two segments of jejunal intussusception resulting in small bowel obstruction, in addition to several lung nodules concerning for metastatic disease (Figure 1).
Surgical consultation was obtained, and the patient was taken for exploratory laparotomy and small bowel resection with primary anastomoses of the two separate segments of intussuscepted small bowel. The patient's hospital course was uncomplicated, and he was discharged home on postoperative day 3. At his 2-week follow-up in surgery clinic, the patient was found to be recovering well. By that time, surgical pathology was finalized, after thorough analysis and expert consultation. The     can be classified based on the cell-lineage they resemble (e.g., smooth muscle, fibroblast, adipocyte, bone, etc.). Not uncommonly, however, the irregularity and degree of dedifferentiation of the tumor cells make determination of cell-lineage impossible; these tumors are thus named based on their morphologic appearance [4]. Spindle cell sarcoma, for example, is characterized by its long, narrow, spindle-like appearance microscopically.
Soft tissue sarcomas, including spindle cell sarcomas, are typically diagnosed at an early stage, with less than 15% with metastatic disease at presentation [5]. However, given the aggressive nature of these tumors, approximately one-third of patients with localized soft tissue sarcoma will develop metastatic disease within 5 years, despite adequate initial treatment. Overall survival in patients with soft tissue sarcoma correlates with the stage of the disease, with an approximately 60% 5-year survival rate for localized disease but only 15% for those with distant metastases [6]. Lung is the primary site for distant metastases, but other common sites of metastases include bone, liver, brain, and lymph nodes [5]. The small intestine is an extremely rare location for sarcoma metastasis. Review of the literature reveals only 46 case reports of various subtypes of bone or soft tissue sarcoma with metastases to the small bowel. Of these, 30 patients presented with small bowel intussusception (with or without obstruction) secondary to the metastatic lesion . Other clinical findings that led to the diagnosis of metastatic sarcoma have included obstruction without intussusception (n=6) [37][38][39][40][41][42] gastrointestinal bleeding (n=10) , and bowel perforation (n=6) [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. In one report, metastatic sarcoma to small bowel was found incidentally on imaging in an asymptomatic patient [52].
The most common types of sarcoma reported to have metastasized to the small bowel include osteosarcoma (n=12), angiosarcoma (n=5), rhabdomyosarcoma (n=5), liposarcoma (n=4), and leiomyosarcoma (n=4) ( Table 1).Overall, neoplasms of the small bowel are rare, with the majority being benign lesions (e.g. lipoma, leiomyoma, fibroma, hamartoma, or ectopic gastric or pancreatic tissue). Of all the cancers of the gastrointestinal tract, those found within the small bowel account for only 1-3% [53,54]. Malignancies of the small bowel are most often primary (e.g. adenocarcinoma, gastrointestinal stromal tumors (GIST), neuroendocrine tumor (NET), or non-Hodgkin's lymphoma) [55]; however, metastases from extra-abdominal sites have also been reported. Melanoma represents the most common metastatic tumor to the small bowel, accounting for over 50% [53]. Other cancers with a propensity for small bowel metastases include invasive lobular carcinoma of the breast, adenocarcinoma of the lung, and clear cell carcinoma of the kidney. As demonstrated in our case, metastases from a primary cutaneous spindle cell sarcoma to the small bowel can occur and cause intussusception, but our literature review shows that it is an exceedingly rare problem.  Close attention should be paid to patients with a personal history or extensive family history of malignancy. As illustrated in this case, expert pathologic analysis is integral to establishing an accurate diagnosis and prognosis. Early involvement of the appropriate specialists is recommended whenever cancer is suspected, to help achieve the best possible outcomes for patients via a multidisciplinary approach.