Rapamycin Treatment for Benign Multicystic Peritoneal Mesothelioma: A Rare Disease with a Difficult Management.

BACKGROUND Benign multicystic peritoneal mesothelioma (BMPM) is a rare intra-abdominal tumor. Although considered by many to be benign, this tumor has a high local recurrence rate. Because of its rarity, preoperative diagnosis is difficult and its origin and pathogenesis are uncertain. There are no evidence-based treatment strategies for BMPM. It is agreed that the best treatment strategy for BMPM is the combination of surgical cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). An increasing body of evidence supports a pivotal role of the cytoplasmic serine/threonine kinase mTOR in the development and progression of several neoplastic diseases and specific mTOR inhibitors, including rapamycin, have been suggested as potential therapeutic options for different cancers. CASE REPORT A 65-year-old male with end-stage renal disease on hemodialysis for seven years presented with BMPM. He underwent surgery to remove multiple peritoneal cysts, but four months later he experienced a recurrence of the disease. Immunohistochemistry of the cysts demonstrated a high level of phosphorylation of p70S6 kinase, a downstream mTOR target, and since a target therapy that blocks PI3K/Akt/mTOR pathway has been shown to have a scientific and logical rationale to treat this rare intra-abdominal neoplasia, we started the patient on low dose rapamycin therapy, an mTOR inhibitor. Long-term mTOR inhibition resulted in a complete and stable remission of BMPM. CONCLUSIONS The current case is the first report of BMPM successfully treated with rapamycin, which resulted in a long-lasting response to mTOR inhibition.

Background

Colorectal cancer is one of three most common cancers in men and women worldwide [1]. The rectum is the second most common site for gastrointestinal neuroendocrine tumor (NET); however, it only accounts for 1–2% of all rectal tumors [2]. Although higher stage metastatic carcinoid tumor prognosis is poor and requires molecularly targeted therapies, local stage carcinoid tumor treatment is considered curative after resection, with excellent prognosis. The current literature revealed several cases of concurrent carcinoid tumor and colorectal adenocarcinoma. Here, we report our two cases of synchronous rectal carcinoid and sigmoid colon adenocarcinoma that were diagnosed by colonoscopy. In addition, we conducted a review of the current literature for similar dual gastrointestinal carcinoid and colorectal cancer occurrences.

Case Report

Case #1

A 40-year-old white male presented to the emergency department with a history of hematochezia and abdominal pain for one year. A computerized tomography (CT) scan of abdomen and pelvis was obtained which revealed a focal segment of the sigmoid colon with wall thickening and surrounding prominent lymph nodes. The patient was discharged home on ciprofloxacin and metronidazole therapy. He underwent a colonoscopy one week later. The colonoscopy revealed a 6 cm circumferential, friable, and ulcerated sigmoid colon mass; biopsy revealed moderately differentiated adenocarcinoma. In addition, a 12 mm rectal polyp was also identified and removed with a cold snare. Pathology of this polyp revealed well-differentiated neuroendocrine tumor with free margins (carcinoid tumor; Figure 1A). A CT of the chest was obtained and this was negative for distant metastasis. The patient underwent laparoscopic sigmoidectomy. Pathology was reported as moderately differentiated adenocarcinoma (Figure 1B) invading the peri-colonic fat with eight microscopic adenocarcinoma tumor deposits. Adjuvant chemotherapy, with leucovorin calcium, 5-fluorouracil, and oxaliplatin-6, was started 4-weeks postoperatively.

Figure 1.

(A) Well differentiated neuroendocrine tumor, grade 1 (carcinoid tumor), synaptophysin immunostain at 400× magnification. (B) Moderately differentiated invasive adenocarcinoma, H&E stain at 200× magnification.

Case #2

A 70-year-old male with a history of bright red blood per rectum (BRBPR) underwent CT scan of abdomen and colonoscopy procedures. Stage III adenocarcinoma of the sigmoid colon was detected. Also, a 10 mm rectal polyp was snared and its pathology was consistent with carcinoid tumor with free margins (Figure 2). The patient underwent laparoscopic sigmoidectomy and received adjuvant chemotherapy with 5-fluorouracil and leucovorin. Recent follow-up colonoscopy was negative.

Figure 2.

(A) Well differentiated neuroendocrine tumor (carcinoid tumor), H&E stain at 200× magnification. (B) Moderately differentiated invasive adenocarcinoma, H&E stain at 100× magnification.

Discussion

While colorectal adenocarcinoma is one of the three most common newly diagnosed internal malignancies in the USA, neuroendocrine tumors are rare and only represent 0.5% of all newly diagnosed cancers with the most common site being the gastrointestinal tract [1]. Dual gastrointestinal carcinoid and colorectal cancer can occur. We conducted a review of the literature and summarized the reported cases with both dual gastrointestinal carcinoid tumor and colorectal adenocarcinoma in Table 1. The first reported case of synchronous carcinoids with non-carcinoid gastrointestinal tract neoplasm was documented in 1949 by Pearson and Fitzgerald [3]. A literature review conducted by Wohaldo et al. in 2010 includes seven presentations of co-existent carcinoid and adenocarcinoma of the gastrointestinal tract [4]. In a study by Cokmert et al. in 2013, there was a report of a high-grade neuroendocrine carcinoma located in the ampulla of Vater with synchronous sigmoid colon adenocarcinoma [5]. Data collected by Zhu et al. in 2015 includes a case of synchronous collision neuroendocrine and adenocarcinoma of the rectum [6] and most recently there was a case report of synchronous sigmoid adenocarcinoma and NET of the descending colon [7].

Table 1.

The literature review of cases with both gastrointestinal carcinoid tumor and colon adenocarcinoma.

No	Author (Reference #)	Age	Sex	Location of carcinoid	Location of colon adenocarcinoma	Treatment
1	Pearson and Fitzgerald [3]	88	M	Ileum	Descending colon	N/A
2	Pearson and Fitzgerald [3]	73	M	Stomach	Sigmoid colon	N/A
3	Pearson and Fitzgerald [3]	61	F	Ileum	Descending colon	N/A
4	Cokmert et al. [5]	63	F	Ampulla of vater	Sigmoid colon	Pancreato-duodenectomy, Left hemicolectomy
5	Zhu et al. [6]	64	F	Rectum	Rectum	Low anterior resection of rectum
6	Mohapatra et al. [7]	83	M	Descending colon	Sigmoid colon	Left hemicolectomy
7	Kucinski et al. [17]	72	F	Ileum	Transverse colon	Right hemicolectomy
8	Tse et al. [18]	72	N/A	Ileum	Hepatic flexure of colon	Right hemicolectomy
9	McHugh et al. [19]	74	F	Ileum	Rectum	Anterior rectal resection with segmental resection of the ileum
10	Khubchandani et al. [20]	53	F	Rectum	Rectum	Anterior rectal resection
11	Sacchi et al. [21]	57	N/A	Ileum	Ascending colon	Right hemicolectomy
12	Habal et al. [22]	52	N/A	Rectum	Sigmoid colon	Resection of the sigmoid colon and rectum
13	Cioffi et al. [23]	64	F	Ileum	Ileum	Resection of distal ileum and cecum
14	Aslam et al. [24]	67	F	ileocecal junction	Sigmoid colon	Subtotal colectomy & resection of terminal ileum
15	Vootla et al. [25]	46	F	Rectal	Hepatic flexure of colon	Right hemicolectomy and adjuvant chemotherapy
16	Present case 1	40	M	Rectum	Sigmoid colon	Snare resection of rectal carcinoid, sigmoid resection and adjuvant chemotherapy
17	Present case 2	70	M	Rectum	Sigmoid colon	Snare resection of rectal carcinoid, sigmoid resection and adjuvant chemotherapy

Including our two cases, of the total 17 synchronous carcinoid tumor and colon carcinoma cases reported, nine were females and five were males. The gender in three dual tumor cases was not reported. The median age of these 17 double primary malignant tumor cases was 64 years (range 40–88 years). Sixth decade and higher median age may increase the risk for both types of primary malignant tumors to occur. However, these synchronous tumors can occur even at “early age”, as one of our cases was the youngest case in the literature (Table 1).

Rectal carcinoids only account for 1–2% of all rectal tumors [8]. Tichansky et al. reported that 8% of patients with colorectal carcinoid also had synchronous cancer [9]. While rectal carcinoids are typically nonfunctioning and asymptomatic, their presence should raise awareness of a potential synchronous colorectal cancer [10] as observed in our cases. The rectum was the second most common location of carcinoid tumors (6/17) after the ileum (8/17) involvement in synchronous carcinoid and colon adenocarcinoma cases. Our two presented cases also had rectum carcinoid tumors. The most common adenocarcinoma location in these double primary malignant tumor cases was sigmoid colon (7/17) including our two cases (Table 1).

The pathogenesis of the association between colorectal adenocarcinoma and NET remains unclear. A theory proposed by Kato et al. suggests a common stem cell which may undergo similar genetic mutations and give rise to different types of gastrointestinal malignancies. It was reported that a CK20 positive NET was detected in a patient with a synchronous colorectal adenocarcinoma, which is a common marker detected in colorectal adenocarcinomas [11]. Another study by Reim et al. suggested roles of gastrin and cholecystokinin in tissue growth of NET in the gastrointestinal tract with subsequent transformation into colorectal and gastric cancers [12]. The relationship between NET and secondary gastrointestinal malignancies was also suggested in a study by Prommegger et al., who studied 96 patients with NET and found that 14 patients had NET and a second primary cancer [13]. Aoyagi et al. suggested a connection between NET and differentiated tubular adenocarcinoma [14].

The European Neuroendocrine Tumor Society (ENETS) provided the most recent colorectal NET guideline in 2016. Endoscopic resection by simple polypectomy or endoscopic mucosal re-section (EMR) with modified EMR band ligation were given as treatment options for NETs with no involvement of the muscularis propria. However, if a resection margin shows an incomplete border, then endoscopic submucosal dissection (ESD) and transanal endoscopic microsurgery (TEMS) would be indicated as adequate treatment. Simple polypectomy was enough for complete removal of NETs in both of our cases, as shown by free resection margins [15].

There are no current guidelines for an increased interval of surveillance colonoscopy after detection of gastrointestinal carcinoid [13,14] or gastrointestinal stromal tumor [16]. If a gastrointestinal carcinoid tumor is diagnosed through colonoscopy, timely management is necessary. However, there is no guideline for these synchronous tumors’ surveillance. We recommended a close surveillance follow-up given their potential synchronous relationship.

Conclusion

The coexistence of carcinoid tumor and colorectal adenocarcinoma is rare with a total of 17 cases, including our two cases, reported in the literature. We recommend that carcinoid tumor may be another colorectal cancer risk factor with the similar mutations and common genetic markers. Dual primary malignant tumors can be diagnosed by endoscopic procedures. We are hoping that our two cases serve as a simulative impulse for clinicians to do colonoscopy when or if they diagnose any gastrointestinal carcinoid tumor. Detection of any carcinoid warrants thorough evaluation of the whole colon for colorectal cancer and close surveillance so that timely management can be achieved.