Skeletal muscle metastasis from signet ring cell esophageal adenocarcinoma

Symptomatic skeletal muscle metastasis from esophageal adenocarcinoma is rare. Here we report the case of a 49-year-old man who presented with right thigh pain, and was found to have symptomatic psoas muscle metastasis as the presentation of esophageal adenocarcinoma. The primary tumor was notable for signet ring cells (SRC), a poor prognostic indicator as well as a predictor of biologic aggressiveness. The patient passed away within 1 month of diagnosis due to disease progression, supporting the aggressiveness of such SRC esophageal lesions. Lastly, a literature review reveals a differential pattern of metastatic spread between esophageal adenocarcinomas and squamous cell carcinomas as regards muscle metastases. Skeletal muscle metastases are more likely to be due to esophageal adenocarcinoma, whereas myocardial metastases are almost exclusively due to esophageal squamous cell carcinoma (ESCC). These differences may represent an example of the ‘seed and soil’ hypothesis of metastasis.