Calcified mucinous adenocarcinoma of the stomach metastatic to the iris: a case report

BACKGROUND: Gastric cancer has a wide spectrum of clinical features, imaging manifestations, and pathology. Punctate calcifications in gastric cancer are infrequent but are usually found in mucinous adenocarcinoma. However, there have only been a few autopsy case reports describing the correlation between the radiology and pathology findings of calcified mucinous adenocarcinoma of the stomach. We present an autopsy case of mucinous gastric adenocarcinoma with iris metastases as the initial symptom. CASE PRESENTATION: A 74-year-old Japanese woman presented with blurred vision. Her treating ophthalmologist diagnosed acute iritis with secondary glaucoma. The histopathological and immunohistochemical features of a trabeculectomy specimen favored metastatic carcinoma, most likely of gastrointestinal tract origin. Esophagogastroduodenoscopy revealed multiple irregularly shaped ulcerative lesions, multiple erosions, and thickened folds in the corpus of her stomach. Histologic examination of a gastric tissue specimen obtained by endoscopic biopsy revealed poorly differentiated carcinoma with signet ring cell features. Computed tomography revealed a tumor with multiple punctate calcifications in the thickened gastric wall with diffuse low attenuation and multiple lymph node metastases, including the para-aortic lymph nodes, and peritoneal dissemination. She was diagnosed with stage IV gastric cancer (T4N3M1) and underwent seven cycles of 5-weekly TS-1, a novel oral fluoropyrimidine derivative, plus cisplatin therapy. Serial follow-up computed tomography revealed successive increases in the gastric wall calcifications. Her disease stabilized, but she died of aspiration pneumonia 8 months after the first visit. Autopsy tissue specimens had miliary, punctate calcifications present in abundant extracellular mucin pools in the submucosa, corresponding to the thickened low-attenuating middle layer on computed tomography. The final diagnosis was mucinous gastric adenocarcinoma because mucinous adenocarcinoma is diagnosed when more than half of the tumor area contains extracellular mucin pools. CONCLUSIONS: We report the pathology and computed tomography imaging characteristics of a case of calcified mucinous adenocarcinoma of the stomach metastatic to the iris, including findings at autopsy. Metastatic carcinomas in the iris originating in the stomach are exceedingly rare. Multiple punctate calcifications were present in pools of extracellular mucin, a diagnostic clue for mucinous adenocarcinoma. Possible mechanisms underlying scattered punctuate calcifications in gastric mucinous adenocarcinoma warrant further investigation.