Early gastric cancer with diffuse heterotopic gastric glands and granular cell tumors mimicking advanced gastric cancer

INTRODUCTION: Heterotopic gastric grands (HGGs) are gastric grands that are observed in the submucosa and are considered to be paracancerous lesions or precursors of gastric cancer (GC). Granular cell tumors (GCTs) are benign neural origin tumors. Gastrointestinal GCTs are rare and gastric GCTs are seldom seen. We report the case of a patient who was diagnosed with early GC with diffuse HGGs affecting the whole stomach and two GCTs mimicking advanced GC. PRESENTATION OF CASE: The patient is a 71-year-old male with epigastric discomfort. Gastrointestinal endoscopy revealed an ulcerated lesion at the mid-gastric body. A biopsy specimen indicated adenocarcinoma. Moreover, gastrointestinal endoscopy revealed a submucosal tumor at the posterior wall and multiple transparent protuberances across the entire stomach. Computed tomography demonstrated diffuse gastric wall thickening with lymphadenopathies. Total gastrectomy was performed under the preoperative diagnosis of advanced GC with lymph node metastases. The pathological diagnosis was adenocarcinoma invading submucosal stroma without lymph node metastasis, two GCTs, and diffuse HGGs affecting whole stomach. DISCUSSION: Preoperative diagnosis of GC depth or range associated with HGGs is often difficult. Although diffuse HGGs are sometimes observed, there is no previous report of a case of HGGs with whole gastric wall thickening observed by computed tomography. As a result, this case was overdiagnosed as advanced GC. Although the relationship between GCTs and HGGs or GC is unclear, there is no case report of GCTs accompanied by HGGs or GC. CONCLUSION: This case report suggested that cautious preoperative assessment for GC co-occurring with HGGs is required.