# Benign yet deceptive: A rare spindle-cell neoplasm mimicking a cystic tumor - A case report on gastric schwannoma

## TL;DR

A rare benign stomach tumor called gastric schwannoma was diagnosed in a patient and successfully treated with surgery, highlighting the importance of accurate diagnosis to avoid mistaking it for a more serious tumor.

## Contribution

This case report emphasizes the diagnostic challenges of gastric schwannomas and the necessity of immunohistochemistry for differentiation from gastrointestinal stromal tumors.

## Key findings

- Gastric schwannomas are rare, benign tumors that can mimic gastrointestinal stromal tumors (GISTs) but are confirmed via immunohistochemistry.
- Complete surgical resection of gastric schwannomas is curative with no recurrence reported.
- Contrast CT and histopathological analysis are essential for accurate diagnosis and treatment planning.

## Abstract

Gastric schwannomas are uncommon, benign tumors originating from Schwann cells within the enteric nerve plexus, comprising 6.3 % of mesenchymal tumors in the stomach and 0.2 % of all gastric neoplasms. Due to their submucosal origin and spindle-cell structure, they can resemble gastrointestinal stromal tumors (GISTs), making immuno-histochemical analysis crucial for accurate diagnosis.

A 61-year-old woman presented with a progressively enlarging abdominal mass over the past five months, with no pain, nausea, or gastrointestinal bleeding. Physical examination revealed a firm, mobile mass measuring 8 × 7 cm2. Routine investigations were inconclusive. Upper gastrointestinal endoscopy showed gastric erosions but no concerning mass. A contrast-enhanced CT scan identified a well-defined, predominantly cystic mass arising from the greater curvature of the stomach.

The patient underwent laparoscopic wedge resection in which the tumor and a portion of the adjacent stomach were resected and histopathological examination confirmed a well-defined spindle-cell tumor with mild nuclear pleomorphism. Immunohistochemistry showed strong positivity for S-100 and Sox-10 proteins, confirming gastric schwannoma. The patient recovered well after surgery with no complications. She was discharged in stable condition, and follow-up evaluations were unremarkable in the short term.

Gastric schwannomas are slow-growing, benign tumors with an excellent prognosis. Differentiation from gastrointestinal stromal tumors is crucial for proper treatment planning. Complete surgical resection is curative, and recurrence is rare, emphasizing the importance of accurate diagnosis for optimal patient care.

•Rare, benign tumors originating from Schwann cells within the enteric nerve plexus•Tumors closely resemble gastrointestinal stromal tumors (GISTs), mandating immuno-histochemical analysis for accurate diagnosis•Contrast CT and histopathology are key to differentiating gastric schwannomas from other gastric tumors.•Surgical resection remains definitive treatment with a good prognosis and no reported cases of recurrence post complete tumor removal

Rare, benign tumors originating from Schwann cells within the enteric nerve plexus

Tumors closely resemble gastrointestinal stromal tumors (GISTs), mandating immuno-histochemical analysis for accurate diagnosis

Contrast CT and histopathology are key to differentiating gastric schwannomas from other gastric tumors.

Surgical resection remains definitive treatment with a good prognosis and no reported cases of recurrence post complete tumor removal