Clinicopathologic findings in a cohort of metastases to the stomach.

Aims: Metastatic tumors to the stomach can mimic primary gastric adenocarcinoma or be subtle and difficult to identify. The current study aimed to characterize the clinicopathology of metastases to the stomach to aid in diagnosis.

Methods And Results: Forty-three metastatic tumors and 30 primary gastric adenocarcinoma cases were reviewed. Metastases originated from numerous primaries with the most common being mammary (n = 17) or melanoma (n = 9). The gastric metastasis represented the initial diagnosis for 9 (21%) cases without previous history of malignancy. The median age at diagnosis was similar (metastatic 66 years; primary 67.5 years; P = 0.42). The most common indication for procedure was abdominal pain (23%; P = 0.95) in metastases and melena (43%; P < 0.01) in primaries. Procedural findings suggestive of metastasis over primary adenocarcinoma were multiple lesions (23% versus 0%; P = 0.01), non-mass forming mucosal changes (30% versus 0%; P < 0.01), submucosal nodularity (14% versus 0%; P = 0.09), and absence of ulceration (9% versus 53%; P < 0.01). Histologic findings less commonly seen in metastasis were mucosal layer involvement (86% versus 100%; P = 0.09), ulceration (40% versus 70%; P = 0.02), surface epithelial involvement/colonization by tumor (12% versus 60%; P < 0.01), intestinal metaplasia (9% versus 53%; P < 0.01), background dysplasia (0% versus 30%; P < 0.01), and Helicobacter pylori infection (0% versus 20%; P < 0.01). Lymphovascular invasion had similar prevalence (metastatic 23%; primary 20%; P = 0.70).

Conclusions: Metastasis to the stomach included a variety of primary sites and was not infrequently the initial diagnosis. Patient demographics were similar to primary adenocarcinoma. Multiple lesions, non-mass forming mucosal changes, and/or submucosal nodularity were more common in metastasis. Histologically, the absence of surface epithelial involvement, ulceration, intestinal metaplasia, background dysplasia, or H. pylori infection can raise suspicion for metastasis.