Gastric Signet-Ring-Cell Adenocarcinoma with Delayed Retroperitoneal Metastasis and Fibrosis.

Gastric signet-ring-cell adenocarcinoma (SRCC) is a rare disease entity, often characterized by early age of the onset and sometimes attributable to heritable genetic mutations. Overall prognosis is usually poor due to diagnosis at late stages. There are a handful of case reports that describe patient presentation with retroperitoneal fibrosis secondary to malignancy from a concurrent gastric SRCC found on the workup. No information exists on timing from primary tumor development to retroperitoneal disease. Further, there is speculation that gastric SRCC may have an indolent phase prior to symptomatic disease, but its natural history is essentially entirely unknown. In this case report, we describe a 39-year-old male with an incidentally discovered gastric SRCC who then underwent multimodality treatment with curative intent. No evidence of recurrence was documented on interval surveillance scans for 4.5 years, at which point, he rapidly developed a large retroperitoneal mass that was biopsied for metastatic disease. He succumbed to his pathology within 6 months. This presentation suggests that gastric SRCC could have both a relatively long indolent phase and an unpredictable propensity for explosive metastatic progression. Tumor biology factors that affect this balance are not understood.