Introduction

Intussusception, although common in the pediatric population, rarely occurs in adults. Furthermore, patients often show nonspecific symptoms. Most adult patients with intussusception have a surgical lead point, a well-defined pathological abnormality, often accurately diagnosed after surgery. A low-grade appendiceal mucinous neoplasm (LAMN), often misdiagnosed as acute appendicitis, is rarely associated with the development of intussusception. Here we report a case of LAMN-related ileocolic intussusception that was histologically diagnosed after laparoscopic right hemicolectomy.

Case presentation

A 58-year-old woman visited our emergency department because of intermittent episodes of epigastric pain with periumbilical tenderness. These symptoms persisted intermittently for 2 weeks. The pain was moderate in severity, colicky in nature, and sometimes shifted to the lower abdominal region. Abdominal computed tomography indicated intussusception with ileocecal and mesenteric telescoping into the transverse colon. Complete colonoscopy with reduction of intussusception was performed, revealing a ball-like mass protruding and occupying the entire cecum lumen. Laparoscopic right hemicolectomy was then performed. Macroscopically, a dilated appendix was revealed with mucin content, along with hyalinization and fibrosis of the appendiceal wall. Microscopically, a tumor exhibiting villous and flat proliferation of mucinous epithelial cells with low-grade nuclear atypia was seen. However, there was no infiltration growth of the tumor cells, thereby demonstrating LAMN. Postoperative recovery was uneventful, and the patient was discharged on the 8th postoperative day without surgical complications.

Conclusion

The differential diagnoses of chronic and colicky abdominal pain should be expanded to include intussusceptions as they can be severe, although cases in adults are rare.

Intussusception is most commonly observed in early childhood with idiopathic causes. In contrast, it rarely occurs in adults, and almost 90% of the incidence results from a pathologic condition that acts as a lead point.1  Computed tomography (CT) of the abdomen is the most practical imaging tool for the diagnosis of an intussusception. As adult intussusceptions have a higher risk of malignancy, an aggressive surgical approach is suggested. Low-grade appendiceal mucinous neoplasm (LAMN) is often misdiagnosed as acute appendicitis and is mostly revealed pathologically after an appendectomy following multiple investigations. LAMN-induced intussusception is extremely rare.

Herein, we describe a rare case involving a 58-year-old woman who presented with intermittent episodes of colicky abdominal pain that occurred intermittently for 2 weeks, resulting from an ileocolic intussusception of the transverse colon secondary to an LAMN that was histologically diagnosed after a successful laparoscopic right hemicolectomy.

Informed consent was obtained from the patient for the purpose of publication.

Chief complaints

A 58-year-old, nonsmoking, multiparous woman presented to our emergency department complaining of intermittent episodes of epigastric pain with periumbilical tenderness that occurred intermittently for 2 weeks.

History of present illness

The patient's abdominal pain had occurred intermittently for the last 2 weeks; the pain was moderate in severity, colicky in nature, and sometimes shifted to the lower abdominal region. She did not report any symptoms of nausea, vomiting, or melena. She had visited the outpatient department several times for further examinations during this period, but no specific findings or obvious symptomatic relief was noticed.

History of illness

She had no history of previous abdominal surgery or allergies but had a history of iron-deficiency anemia that was managed with ferrous fumarate supplements.

Personal and family history

The patient did not have a history of tobacco smoking or alcohol consumption. There was no noteworthy family medical history, including that of cancer or abdominal diseases.

Physical examination on admission

The patient's height and weight were 157 cm and 52 kg, respectively. The patient had a clear sensorium but was ill looking, with a body temperature of 36.7°C, a blood pressure of 110/57 mm Hg, and a pulse rate of 77 beats/min. An abdominal examination revealed normal results, including normal bowel gurgling sounds and no tympanic percussion sounds, and there was no palpable mass. However, moderate tenderness was present over the right lower quadrant of the abdomen.

Diagnostic assessments

An abdominal X-ray (Fig. 1) was performed first, which revealed moderate ileus and increased soft tissue density in the right lower quadrant of the abdomen. Owing to the long-lasting unspecified chronic abdominal pain, we then performed abdominal CT scans (Fig. 2), which showed characteristics of adult intussusception with ileocecal and mesenteric telescoping into the transverse colon, with the leading point below the umbilicus. Total colonoscopy (Fig. 3) was performed, revealing a ball-like mass with a regular surface protruding into the ileocecal valve region, which was occupying the entire lumen. Reduction was performed, and biopsies were taken from the mass lesion. Chest radiography was performed, and no tumors were noted in the lungs.

Fig. 1

Radiography of the abdomen showing a moderate ileus without definite mechanical obstruction (arrow); in addition, increased soft-tissue density in the right lower quadrant of the abdomen was also observed (arrowhead).

Fig. 1

Radiography of the abdomen showing a moderate ileus without definite mechanical obstruction (arrow); in addition, increased soft-tissue density in the right lower quadrant of the abdomen was also observed (arrowhead).

Close modal
Fig. 2

An abdominal CT scan showing in axial view: (a) invaginated mesenteric fat and vessels telescoping into the transverse colon and (b) the target sign of the ileocolic intussusception due to change in edema with mural thickness. The coronal view (c) demonstrates an ileocolic intussusception with a lead point (d) ileocolic intussusception of the transverse colon (arrow).

Fig. 2

An abdominal CT scan showing in axial view: (a) invaginated mesenteric fat and vessels telescoping into the transverse colon and (b) the target sign of the ileocolic intussusception due to change in edema with mural thickness. The coronal view (c) demonstrates an ileocolic intussusception with a lead point (d) ileocolic intussusception of the transverse colon (arrow).

Close modal
Fig. 3

A colonoscopic picture showing (a) a ball-like mass with regular surface. (b) Sample extraction for a biopsy.

Fig. 3

A colonoscopic picture showing (a) a ball-like mass with regular surface. (b) Sample extraction for a biopsy.

Close modal

Therapeutic interventions

Surgery

The biopsied specimen from the colonoscopy revealed proliferative glandular cells with preserved polarity and nonwhole layered stratification, suggesting low-grade dysplasia along with focal necrosis. The tentative diagnosis was a tumor-leading-point-related ileocolic intussusception. We then performed a laparoscopic right hemicolectomy, followed by anastomosis of the ileum and transverse colon.

Pathologic findings

Macroscopically (Fig. 4), the specimen consisted of a segment from the right hemicolectomy measuring 13 cm in length, including the ileocecal valve containing 9.8 cm of cecum and 3.2 cm of the terminal ileum; a dilated appendix with mucin content measuring 5 × 3.5 cm in dimension; hyalinization and fibrosis of the appendiceal wall; and pericolonic fat of the cecal region. Histologically (Fig. 5), the LAMN showed villous and flat proliferation of mucinous epithelial cells with low-grade nuclear atypia associated with atrophy of the underlying lymphoid tissue without infiltrating growth of the tumor cells. The tumor cells were immunoreactive for cytokeratin 20 (CK20) and caudal type homeobox 2 (CDX2). No regional lymph nodes were observed.

Fig. 4

Specimen: A macroscopic view showing a dilated appendix with mucin content in the cecal region.

Fig. 4

Specimen: A macroscopic view showing a dilated appendix with mucin content in the cecal region.

Close modal
Fig. 5

Histopathologic report. (a) Replacement of the normal appendiceal mucosa with abundant mucin and villous mucinous epithelial proliferation with atrophy of the underlying lymphoid tissue, H&E 40×. (b) Slender villi lined by tall mucinous epithelial cells with low-grade cytologic atypia and remaining cell polarity, H&E 400×.

Fig. 5

Histopathologic report. (a) Replacement of the normal appendiceal mucosa with abundant mucin and villous mucinous epithelial proliferation with atrophy of the underlying lymphoid tissue, H&E 40×. (b) Slender villi lined by tall mucinous epithelial cells with low-grade cytologic atypia and remaining cell polarity, H&E 400×.

Close modal

Final diagnosis

The final diagnosis of the resected tumor lesion was an LAMN.

Follow-up and outcomes

Postoperative recovery was smooth, and the patient was discharged on the 8th postoperative day without surgical complications. Biannual follow-up examinations with imaging, including CT scans of the abdomen and pelvis, were scheduled to be performed within 2 years after the surgery.

Intussusception can occur at any age, but it is most commonly observed in children. Approximately 5% of intussusceptions present in adults,2  and approximately 90% of adult intussusceptions occur in the small or large bowel. Based on the position in which it occurs, intussusceptions are classified into 4 categories: entero-enteric; colo-colic; ileo-colic, in which the terminal ileum may telescope within the ascending colon; and ileo-cecal, where the ileo-cecal valve is the most common leading point.3  The most common type is entero-enteric, followed by the colo-colic, ileo-cecal, and ileocolic types.46  The prevalence is nearly equal between the sexes in adults.7  The highest occurrence rate is in the 30- to 50-year-old age range.2,8  The overall incidence of intussusception in adults is approximately 2 to 3 cases per 1,000,000 in the general population annually.9  Our patient was a 58-year-old female with ileocolic intussusception of the transverse colon.

Pediatric intussusceptions often present acutely with the classic triad of a painful sensation in the abdomen, stools mixed with blood and mucus (often referred to as “currant-jelly” stools), and a palpable tender abdominal mass.10  Adult intussusceptions often present variably and have nonspecific symptoms similar to those of intestinal obstruction. The most common symptom of an adult intussusception is an initial sensation of pain in the abdomen, followed by nausea and vomiting.2,7,11  The presentation of pain is often chronic, intermittent or periodic, posing a challenge in terms of diagnosis. Only slightly more than half of all cases are diagnosed before surgery.7,12 

Approximately 90% of cases of adult intussusception have a lead point, which is a well-defined pathologic abnormality. A significant proportion of these lead points are malignant neoplasms, and, of these, 66% are colonic cases and 30% are small intestine cases.10  According to the data reported, the most common malignant lead point in the colon is an adenocarcinoma, and the most common malignant lead point in the small intestine is a metastasis.10,13  In our case, a malignant etiology was detected for the ileocolic intussusception.

Laboratory tests are nonspecific for cases of adult intussusception, but bowel perforation or compromise may occur. A plain abdominal radiograph is the first diagnostic tool for examining signs of intestinal obstruction, providing information on the site of obstruction.14  A flexible colonoscopy is a valuable tool for the evaluation of patients with intussusceptions that present with signs of large bowel obstruction, which can be either subacute or chronic in nature. The main advantages of a colonoscopy are the diagnosis of intussusception, its ability to pinpoint the site of localization, and its ability to assist with treatment. The treatment is often preoperative reduction based on the underlying lesion serving as a lead point.11 

An abdominal CT scan is at present widely regarded as the most essential tool for diagnosing adult intussusceptions, which often appear as a complex target-like soft tissue mass.15,16  The mass consists of a central intussusceptum and outer intussuscipiens, separated by mesenteric fat that appears as a low-attenuation layer.17  The image impression varies because of the location, section axis, bowel wall thickness, and lumen patency. An intussusception with a lead point demonstrates an abnormal target-like mass with a cross-sectional diameter greater than the normal bowel size. Proximal bowel obstruction may also be present.17,18  However, although an abdominal CT scan has been viewed as the foremost diagnostic tool for an intussusception, distinguishing between the distinct anatomic features of the leading mass is not easy because of poor discrimination from the edematous intestinal wall.

The traditional management of symptomatic adult intussusceptions involves an exploratory laparotomy or laparoscopy with resection of the lead point masses or areas of ischemia.10  Considering the theoretical risks of perforation and the potential seeding of malignant tumor cells during manipulation, preoperative reduction is generally not recommended.13,19  However, the optimal choice of surgery remains controversial. A systematic review and meta-analysis consisting of 40 retrospective cases that included 1229 eligible patients concluded that the management of intussusceptions can differ because of the location of the leading mass point and the specific clinical presentations.7  For instance, an obvious case of colo-colic intussusception and an inflamed, friable, or ischemic bowel should undergo resection without attempting reduction because of its high potential of malignancy and emergency events, such as hallow organ perforation.2,7,11  Several studies recommend that a reduction should be tried before resection in the absence of ischemic changes and primary malignant lesions.7,20,21  With respect to our patient, she presented with a prolonged duration of chronic abdominal pain. Additionally, although clinical findings revealed that ileocecal and mesenteric fat and vessels had telescoped into the transverse colon, the precise location of the leading mass point could not be accurately identified. In addition, radiography is restricted in its use as it is unable to distinguish between malignant and benign leading points. Because there were no indications of an overt bowel obstruction or ischemia, we performed a colonoscopy for reduction. It also localized the leading point of the tumor and enabled the retrieval of a specimen for biopsy. In our case, because the tumor was first noticed over the cecal region, a laparoscopic right hemicolectomy was considered the first priority compared with the standard treatment of colon cancer.

Appendix neoplasms are rare and are found in lower than 2% of surgically removed appendices.22  Appendiceal mucinous neoplasm is a rare and heterogeneous disease accounting for lesser than 1% of all cancer cases.23  LAMN is a confined appendiceal neoplasm characterized by noninvasive mucinous epithelial proliferation with extracellular mucin in the absence of infiltrative growth. Furthermore, LAMNs have an excellent prognosis because these tumors are restricted. However, an LAMN may develop malignant potential once the tumors penetrate the appendicular wall, thereby spreading in the peritoneal cavity with gelatinous deposits and contributing to pseudomyxoma peritonei (PMP).22,23  An LAMN is often initially misdiagnosed as acute appendicitis, retroperitoneal tumors in the right iliac fossa, or adnexal mass24  and is mostly revealed pathologically after an appendectomy.25  Patients with LAMNs at presentation tend to be in the 6th decade of life, and there is no clear sex predilection.26  Complications of LAMN include intussusception, ureteral obstruction, volvulus, small bowel obstruction, rupture, and PMP.24  Elevation of carcinoembryonic antigen, carbohydrate antigen 19-9, and carbohydrate antigen 125 levels are noted in 56.1% to 67.1% of patients with LAMN.27,28  Owing to its low incidence, with no more than 2% cases of nodal spread in well-differentiated localized appendiceal tumors, a simple appendectomy is mostly suggested for tumors exhibiting only local disease.23,26,28,29  Right hemicolectomy is considered for tumors involving the peri-appendiceal area, those with sizes larger than 2 cm, those with high-grade histology, and those that invade through the muscularis propria.30,31  Statistics have shown that the 5-year survival rate associated with a localized LAMN is 95%.28  Adjuvant chemotherapy is not advised for low-grade well-differentiated mucinous tumors, unless specific situations related to invasive features arise, for instance, lymph node involvement.23  Radiographic imaging every 6 months after surgery for 2 years should be considered as the optimum monitoring standard for patients with LAMN to adequately monitor tumor recurrence and complications associated with PMP.28,32 

In our case, laparoscopic right hemicolectomy was performed first based on the suspicion of high-risk malignancy of the colon leading to colic intussusception, and an LAMN was pathologically diagnosed after the surgery. However, for the treatment of the LAMN, because the tumor size was larger than 2 cm and it involved the peri-appendiceal lumen, a laparoscopic right hemicolectomy was the appropriate surgical choice. Conclusive treatment was completed in this case, and pathologic confirmation was obtained. Follow-up continued for 2 to 5 years after surgery was suggested to the patient; also, physical examinations, a biannual CT scan of the abdomen and pelvis, and monitoring of tumor markers were recommended.

An intussusception in adults is difficult to diagnose preoperatively because of nonspecific symptoms. The exact cause of an intussusception is often accurately diagnosed after surgery. A flexible colonoscopy is a valuable tool for the evaluation of patients with intussusceptions present with signs of large bowel obstruction, with advantages of diagnosis of intussusception, lesion site localization, and the ability to assist with treatment, such as preoperative reduction. However, because high potential of malignancy and emergency events such as hallow organ perforation were alert, only in the absence of ischemic changes and primary malignant lesions should colonoscopy-assisted reduction be tried. An aggressively cautious approach is suggested for colonic intussusceptions because of the high incidence of malignancy. An LAMN is often initially misdiagnosed as acute appendicitis and mostly revealed pathologically after an appendectomy; LAMN-induced intussusception is relatively rare. A simple appendectomy is originally recommended if an LAMN is revealed before the surgery in cases with no documented metastatic involvement of the appendiceal or distal ileocolic lymph nodes. However, for tumors larger than 2 cm, for those involving the peri-appendiceal area, or for those invading through the muscularis propria, a right hemicolectomy should be considered. This was an extremely rare case of ileocolic intussusception of the transverse colon caused by a 5-cm LAMN that protruded into the lumen of the cecum. A laparoscopic right hemicolectomy was performed on account of the initial clinical presentation of colic intussusception. The treatment in this case was completed, and pathologic confirmation was obtained.

G-HL and T-WP performed the surgery, reviewed the literature, and contributed to manuscript drafting; Y-CL performed the histopathologic analyses and interpretation and contributed to manuscript drafting; C-YC performed the oncologic diseases consultation, reviewed the literature, and contributed to manuscript drafting; Y-JC, J-CK, C-WH, C-YC, and J-MH were responsible for the revision of the manuscript for important intellectual content; and all authors issued final approval for the version to be submitted. The authors thank the patient for allowing us to share her details. Informed consent was obtained from the patient for the purpose of publication.

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