Multiple non-polypoid mucosal Schwann cell hamartomas presenting as edematous and submucosal tumor-like lesions: a case report

Abstract

Background Mucosal Schwann cell hamartomas are rare neurogenic tumors which present most commonly in the distal colon. They are usually discovered as small, single polyps in asymptomatic patients. Case presentation An asymptomatic 64-year-old man was referred to us after a 12 mm subepithelial lesion was discovered incidentally on screening colonoscopy. Follow-up colonoscopy conducted 2 months later revealed that the tumor had disappeared, leaving multiple edematous, submucosal tumor-like elevations presenting as skip lesions throughout the sigmoid colon. Lesions had elongated pits on magnifying endoscopy and were limited to the first layer on endoscopic ultrasound. Biopsies revealed unclearly delineated foci of spindle-shaped cells limited to the lamina propria. On immunohistochemistry, all lesions were positive for S-100 protein and negative for CD34, CD56, and neurofilament protein. The patient was diagnosed with multiple mucosal Schwann cell hamartomas of the sigmoid colon. He remains asymptomatic after 18 months of follow-up, but the lesions have also remained unchanged. Conclusion We report a case of multiple non-polypoid mucosal Schwann cell hamartomas. Endoscopic findings may assist in the differential diagnosis, particularly when presenting as non-polypoid, submucosal tumor-like lesions.

A Rare Case of Schwann Cell Hamartoma in the Duodenum

“…With narrow band imaging, granular white opacities were highlighted on the mucosal surface and endoscopic ultrasound highlighted that the lesion was present only in the superficial mucosa. 14…”

Nonpolypous Hamartomas of the Gastrointestinal Tract: An Updated Review on Classification, Denominations, and Clinical Management

“…It is an uncommon sessile lesion of the GI tract mucosa characterized by ill-defined proliferation of Schwann cells in the lamina propria, without whorls, palisading, fasciculation, or necrosis [ 34 , 42 ]. These S100-positive elongated spindle cells have tapering small nuclei and well-defined eosinophilic cytoplasm and are usually negative for neurofilament protein (NFP) [ 34 , 43 , 44 ]. In the past, these lesions were known as neuroma [ 45 ].…”

“…Between 2008 and 2021, other 60 cases were reported. The 86 cases of the appendix ( n = 3), proximal colon ( n 16), distal colon ( n = 57), and rectum ( n = 10) occurred in males and females with a median age of 60.2 years [ 43 , 44 ]. Although Schwann cell hamartoma was considered as exclusively occurring in the colon, a series of 6 cases of gastroesophageal junction was published in 2020 by Li et al [ 45 ].…”

“…As mucosal Schwann cell hamartomas can be multiple (4/86 cases), differential diagnosis includes von Recklinghausen's (type 1) neurofibromatosis, in which the mucosal crypts are not affected, and multiple neuromas from patients with multiple endocrine neoplasia type 2B (MEN 2B) [ 42 – 44 ]. As opposite, schwannoma is well circumscribed but not capsulated, is surrounded by a lymphoid peripheral cuff and is usually a solitary tumor [ 42 , 43 ].…”

“…As opposite, schwannoma is well circumscribed but not capsulated, is surrounded by a lymphoid peripheral cuff and is usually a solitary tumor [ 42 , 43 ]. Schwannoma is more frequent in the distal colon followed by stomach and gastroesophageal junction [ 42 – 44 ]. Solitary ganglioneuroma, neurofibroma (ganglion cells are positive for CD34), leiomyoma (positive for smooth muscle actin), gastrointestinal stromal tumor (GIST), and perineuroma (formerly known as “benign fibroblastic polyp”) should also be excluded [ 34 , 41 , 45 ].…”