Cecal schwannoma: A case report and literature review

Abstract

Schwannomas are slow-growing tumors originating from Schwann cells and are rarely found in the gastrointestinal tract, particularly in the cecum. We report the case of a 59-year-old man who had recurrent diarrhea and was found to have a mass in the cecum during endoscopic examination. Contrast-enhanced abdominal computed tomography revealed a slightly hypodense, homogeneous mass in the cecum with moderate enhancement. The tumor was laparoscopically resected. Histopathological examination indicated spindle-shaped tumor cells arranged in a fascicular or palisading pattern, with minimal cellular atypia and rare mitotic figures. Immunohistochemical staining was positive for S100 and SOX10. The final pathological diagnosis was schwannoma. The patient was followed up for 34 months postoperatively without recurrence or metastasis. Cecal schwannoma is a rare benign neoplasm. We present this case and review the clinical and imaging features of previously reported cases of cecal schwannoma to enhance diagnostic accuracy and improve clinicians’ understanding of this uncommon tumor.

Introduction

Schwannomas are slow-growing tumors derived from Schwann cells and most commonly occur in the head, neck, and extremities. However, schwannomas have been reported in less common sites, including the retroperitoneum, ¹ pelvis, ² right ventricle, ³ scrotum, ⁴ seminal vesicle, ⁵ and bronchi. ⁶ Gastrointestinal schwannomas are rare, accounting for approximately 2%–6% of all schwannomas, ⁷ with the majority occurring in the stomach and only a small proportion arising in the cecum. ⁷ The imaging manifestations of gastrointestinal schwannomas often resemble those of other mesenchymal tumors, making preoperative diagnosis challenging. Nonetheless, most schwannomas are benign with good prognosis. Therefore, improving the diagnostic accuracy of schwannomas is essential for guiding appropriate clinical management.

In this study, we report the case of cecal schwannoma in a 59-year-old man that was initially misdiagnosed as a mucinous tumor or carcinoid. Additionally, we analyzed and summarized the clinical and imaging characteristics of previously reported cases to enhance preoperative diagnostic precision for intestinal schwannomas and avoid unnecessary surgical interventions. This case is reported in accordance with the Case Report (CARE) guidelines. ⁸

Case presentation

A 59-year-old male patient was admitted to the hospital with recurrent diarrhea that had persisted for 4 months. The patient’s medical history showed that the patient had been diagnosed with colonic polyps by colonoscopy at another hospital in February 2022, with pathological findings indicating tubular adenoma with low-grade dysplasia in the ascending colon. In June 2022, the patient underwent endoscopic polypectomy at our hospital, and a lesion was discovered in the cecum. This lesion lacked a stalk and was considered to represent an extrinsic compression. A computed tomography (CT) scan was subsequently recommended for further evaluation. Laboratory tests and tumor marker levels were within the normal limits. Contrast-enhanced abdominal CT demonstrated a well-circumscribed, homogenous, slightly hypodense mass in the cecum with a size of 5.0 × 4.3 cm. The CT attenuation values were 38 Hounsfield units (HUs) on plain scan, 51 HUs in the arterial phase, and 69 HUs in the venous phase, indicating moderate enhancement (Figure 1(a) to (c)). Based on imaging features, a mucinous neoplasm or carcinoid tumor was suspected preoperatively. The patient underwent a laparoscopic right hemicolectomy. Intraoperative exploration revealed a mass located in the cecum, exhibiting an intact capsule protruding outward. The tumor measured approximately 5.0 × 4.0 cm and had mild adhesion to adjacent tissues without infiltration; no enlarged lymph nodes were palpated in the mesentery. No obvious metastatic nodules were present in the liver, small intestine, peritoneum, or pelvic cavity. The tumor was completely resected.

Figure 1.

CT and pathological features of schwannoma of the cecum. (a) Plain scan (axial) showed a well-circumscribed cecal mass. (b and c) Arterial and venous phases. The mass shows moderate enhancement. (d) H&E staining (×100). (e) Immunohistochemical staining showed positivity for S100 (×100) and (f) immunohistochemical staining showed positivity for SOX10 (×100). CT: computed tomography; H&E, hematoxylin–eosin.

Histopathological examination (Figure 1(d) to (f)) revealed spindle-shaped tumor cells arranged in fascicular or palisading patterns, with minimal cytologic atypia and rare mitotic figures. The surgical margins were negative, and none of the 16 examined lymph nodes showed tumor involvement. Immunohistochemistry was negative for Desmin, smooth muscle actin, DOG1, CD34, CD117, and epithelial membrane antigen but diffusely positive for CD68, S100, and SOX10. The Ki-67 proliferation index was low (2%). These findings were consistent with a diagnosis of schwannoma.

No radiotherapy or chemotherapy was performed, and no recurrence or metastasis was observed after 34 months of follow-up with regular CT examinations.

Discussion

Gastrointestinal schwannomas originate from Schwann cells of the nerve sheath within the Auerbach plexus located between the muscular layers of the gastrointestinal wall. The first case was reported in 1988. ⁹ These schwannomas most commonly arise in the stomach, followed by the colon and rectum. ¹⁰ Schwannomas of the cecum are relatively rare, with only approximately 17 cases^7,10–19 reported in the literature (Table 1), primarily as case reports focusing on clinical features with limited imaging descriptions. Among these, imaging characteristics have been documented in only five cases (Table 2). The present study analyzed and summarized the clinical and imaging features of cecal schwannomas.

Table 1.

Clinical and histologic features and outcome of cecal schwannomas.

No.	Authors	Year	No.	Sex/Age (years)	Location	Symptom	Maximum diameter (cm)	Treatment	Follow up
1	Tomozawa et al. 11	1998	1	M/66	cecum	FOBT	3.5	Laparoscopic ileocecal resection	24 months
2	Miettinen et al. 12	2001	6	M/83	cecum near the ileocecal valve	N/A	2.3	Modified right hemicolectomy (13 cm)	28 months
				M/65	cecum 4 cm from the ileocecal valve	Asymptomatic	2.8	Modified right hemicolectomy with ileal resection	54 months
				F/71	cecum, near the ileocecal valve	Rectorrhagia	3.0	Modified right hemicolectomy with ileal resection	203 months
				F/84	cecum	Rectorrhagia	3.9	Enucleation, extramucosally	6 months
				F/18	cecum	Rectorrhagia	5.0	Modified right hemicolectomy with ileal resection	40 months
				M/72	cecum	N/A	5.5	Right hemicolectomy (30 cm)	128 months
3	Inagawa et al. 13	2001	1	M/44	cecum	FOB	1.0	Endoscopic tumor resection	9 months
4	Matsumoto et al. 14	2011	1	M/59	cecum	Asymptomatic	2	Laparoscopic wedge resection	8 months
5	Kanneganti et al. 15	2011	1	F/35	cecum	Melena	4	Right hemicolectomy	N/A
6	De Mesquita Neto et al. 16	2013	1	F/78	cecum	Weight loss	10	Laparotomy	N/A
7	Dickson-Lowe et al. 17	2014	1	M/72	cecum	Rectorrhagia	5	Right hemicolectomy	N/A
8	Turaihi et al. 18	2017	1	F/61	cecum	Rectorrhagia	4	Laparotomy	N/A
9	Bohlok et al. 7	2018	1	F/70	cecum	Asymptomatic	2	Mini-laparotomy	N/A
10	Shu et al. 19	2019	1	M/38	cecum	Abdominal pain	0.6	Endoscopic submucosal dissection	2 weeks
11	Yu et al. 10	2024	2	F/78	cecum	N/A	2.6	N/A	N/A
				M/58	cecum	N/A	1.0	N/A	N/A

F: female; M: male; FOB: fecal occult blood; FOBT: fecal occult blood test.

Table 2.

Imaging features of five cases pathologically proven cecal schwannomas.

No.	Authors	Year	No.	Sex/Age (years)	Growth pattern	Imaging features
1	Tomozawa et al. 11	2011	1	M/59	Mixed	Relatively homogeneous enhancement and well-circumscribed, homogenous enhancement
2	De Mesquita Neto et al. 16	2013	1	F/78	Intraluminal	Well-circumscribed, homogenous low enhancement
3	Dickson-Lowe et al. 17	2014	1	M/72	Intraluminal	Relatively homogeneous enhancement
4	Bohlok et al. 7	2018	1	F/70	N/A	Well-circumscribed, homogenous enhancement
5	Yu et al. 10	2024	1	F/78	Extraluminal	A slightly low-attenuation nodule with progressive obvious enhancement The CT values on the plain CT scan, in the arterial phase, and in the venous phase were 36.4 HUs, 93.6 HUs, and 117.5 HUs, respectively

CT: computed tomography; F: female; HU: Hounsfield unit; M: male.

Previous studies have shown that gastrointestinal schwannomas are more prevalent in women, typically asymptomatic, and often discovered incidentally. Bohlok et al. ⁷ reviewed 70 publications including 95 cases of colorectal schwannomas, reporting a female predominance (58.3%) and an average age at occurrence of 61 years. Similarly, Singh et al. ²⁰ analyzed 44 cases of gastrointestinal schwannomas and found a female prevalence of 63.6% with a mean age at occurrence of 59 years. However, in our review of 17 cases of cecal schwannoma, the male-to-female ratio was approximately 1.1:1, suggesting a nearly equal sex distribution; the average age at occurrence was 62 years. The present case, involving a 59-year-old man, aligns with these findings in terms of age, although there are sex-based differences when compared with the broader literature (Table 1). Tumor sizes reported in gastrointestinal schwannomas vary widely, ranging from 0.3 to 28 cm. In cecal schwannomas, the limited available data suggest a size range of approximately 0.6–10 cm (mean 3.4 cm); the schwannoma in our case had a maximum diameter of 5.0 cm. Further, it was identified incidentally during a colonoscopy performed for diarrhea. Although most reported cases are asymptomatic, symptoms such as bleeding, positive fecal occult blood tests, and abdominal pain have also been described. Tumor-related bleeding could be associated with mucosal ulceration overlying the lesion.

Due to the rarity of cecal schwannomas, imaging features have been inadequately characterized, with only five cases reported in the literature. Most schwannomas appear as well-circumscribed soft tissue masses exhibiting homogeneous enhancement, although the degree of enhancement varies from mild to obvious (Table 2). In our case, the CT attenuation increased by 31 HUs, indicating moderate enhancement, which differs from that in reported cases of cecal schwannomas. Tao et al. ²¹ reported that 14 of the 16 (87.5%) colorectal schwannomas exhibited mild-to-moderate enhancement, whereas Yu et al. ¹⁰ found that 9 of the 11 (81.8%) showed marked enhancement, indicating variability in imaging findings. The enhancement pattern in our case aligns more closely with the findings of Tao et al. ²¹ Of the five reported cecal schwannomas with imaging data (Table 2), three showed intraluminal or mixed growth patterns. The tumor in our case also presented with an intraluminal growth pattern. Tao et al. ²¹ observed that 10 of the 16 (62.5%) colorectal schwannomas had intraluminal or mixed growth pattern. Similarly, Kang et al. ²² showed that 9 of the 13 (69.2%) tumors exhibited endophytic or dumbbell-shaped growth. Conversely, Yu et al. ¹⁰ described a different distribution, with 4 of the 11 (36.4%) demonstrating mixed growth and the rest showing predominantly extraluminal growth. These discrepancies may be attributable to the small number of cases and highlight the need for more comprehensive data for a better understanding of the growth patterns and imaging features. Notably, both our case and those reported in the literature consistently describe a homogeneous tumor appearance, which may reflect the slow growth and resistance of these tumors to necrosis and cystic degeneration.

Gastrointestinal schwannomas should be differentiated from the following tumors: 1. Gastrointestinal stromal tumors (GISTs), which are hypervascular tumors typically exhibiting marked enhancement, with predominantly intra-extraluminal or extraluminal growth patterns. Central hemorrhage and necrosis are common. Immunohistochemical analysis reveals positive expression of CD117 and CD34. In contrast, schwannomas generally demonstrate relatively homogeneous density with progressive enhancement and are immunopositive for S-100 protein. GISTs are potentially malignant; therefore, surgical resection is usually the preferred treatment, whereas schwannomas can be managed conservatively. Therefore, accurate preoperative differentiation between these two tumors is crucial for determining the appropriate treatment plan. Sawafta et al. ²³ reported the case of a schwannoma mimicking GIST growth; the resected specimen showed no necrosis or lymph node enlargement, consistent with typical schwannoma characteristics; 2. carcinoid tumors (neuroendocrine neoplasms) that are most commonly found in the cecum or ascending colon, manifesting as large masses with ulcerative or annular thickening. Although their imaging features resemble those of adenocarcinomas, they exhibit a higher propensity for hepatic metastasis; and 3. gastrointestinal lymphomas that often present with diffuse wall thickening, accompanied with enlarged and confluent adjacent lymph nodes. Intestinal lymphomas may exhibit an “aneurysmal dilatation sign.”

Most gastrointestinal schwannomas are benign, and currently, there are no reported cases of malignancy, recurrence, or metastasis in patients with cecal schwannomas. However, few cases of malignant gastrointestinal schwannomas have been reported. ²⁴ The longest disease-free follow-up period reported for cecal schwannomas is 203 months. ¹² In our case, the patient has remained free of recurrence or metastasis at 34 months of follow-up with CT examinations.

In conclusion, cecal schwannomas are rare and often indistinguishable preoperatively from other submucosal tumors. Based on reported clinical and imaging findings, a well-defined, homogeneous mass in the cecum of an elderly patient with moderate enhancement should raise the suspicion for schwannoma. These tumors typically exhibit benign behavior and slow growth, suggesting that asymptomatic patients may be appropriate candidates for surveillance, thereby avoiding unnecessary surgical intervention.