Mesonephric Remnants of the Diaphragm: A Major Pitfall in a Patient with Oesophageal Carcinoma

Abstract

Mesonephric remnants represent a benign epithelial glandular proliferation derived from the lack of complete regression of the mesonephric ducts in embryogenesis. They are usually incidental findings and can cause confusion and diagnostic failures since they appear as glands outside the context of a glandular organ. Here we introduce the case of an 80-year-old man presented to the Chirurgical Department due to oesophageal stenosis in a context of a signet-ring cell carcinoma of the gastroesophageal junction. The CT-scan study demonstrated liquid retention in the esophagus and peritoneal carcinomatosis was suspected. Laparoscopy revealed multiple white spots on the peritoneal oesophageal hiatus which were biopsied. On microscopic examination, tubular formations with a monomorphic, cubic epithelial lining were seen which showed immunohistochemically a strong reactivity of CK-7 and Ber-EP4 and negativity for TTF-1, WT1, Calretinin, PAX-8, and CDX2 (Figure 2). A local metastasis of the oesophageal carcinoma was excluded based on morphology and immunohistochemistry and the diagnosis of mesonephric remnants was made. Here we present a rare but potentially grave pitfall and to our best knowledge the first case of mesonephric remnants within the diaphragm.