Metastatic Malignant Extra-renal Rhabdoid Tumor (MERT) of the Esophagus

Abstract

Purpose: We report a 61-year-old female who presented with a 5-month history of intermittent dysphagia to solids and an 8-pound weight loss. She underwent a barium swallow that revealed a partially obstructing distal esophageal lesion suspicious for malignancy. She was referred to an outside gastroenterologist for an upper endoscopy (EGD). EGD demonstrated a large, partially obstructing fungating mass in the esophagus from 33 cm to 40 cm. Cold forceps biopsies were performed revealing poorly differentiated non-small cell carcinoma. Immunohistochemistry (IHC) staining was performed for epithelial markers and was positive for epithelial membrane antigen (EMA), cytokeratin AE1/3, and CAM 5.2. The impression was that of an esophageal non-small cell carcinoma. Staging CT scan of the chest, abdomen, and pelvis showed marked concentric wall thickening of the distal esophagus with extensive mediastinal lymphadenopathy and porta caval/hepatis lymph nodes. Subsequent PET scan demonstrated uptake in the distal esophagus and adjacent lymph nodes. She was then referred to us for staging via endoscopic ultrasound (EUS). EUS revealed the partially obstructing fungating mass in the distal esophagus with poorly defined borders and evidence of extension beyond the adventitia. Malignant appearing lymph nodes were seen in the paraesophageal region, gastrohepatic ligament, and the celiac axis. The left adrenal gland also appeared enlarged. EUS-guided fine needle aspiration (EUS-FNA) was performed of a celiac lymph node and the left adrenal gland. Immediate cytological evaluation (ICE) of the celiac lymph node aspirate was positive for malignant cells. Cell block of the celiac lymph node revealed large, poorly cohesive cells with vesicular chromatin, eccentric nuclei with prominent nucleoli, and dense eosinophilic cytoplasmic inclusions. IHC staining for vimentin was performed and was positive; this confirmed a diagnosis of metastatic malignant rhabdoid tumor. Recuts of the outside slides also stained positive for vimentin-consistent with malignant extra-renal rhabdoid tumor (MERT) of the esophagus. MERT of the esophagus is rare and carries a poor prognosis with a 1-year survival of approximately 30%. MERT is defined by the presence of large, poorly cohesive cells with vesicular chromatin, eccentric nuclei with prominent nucleoli, and eosinophilic cytoplasmic inclusions. Co-expression of vimentin and epithelial cytokeratin can assist in confirming the diagnosis. Our patient with metastatic MERT was subsequently referred to an oncologist for chemotherapy (cisplatin and 5-fluorouracil). This rare case demonstrates the importance of maintaining a high suspicion of MERT in patients with esophageal non-small cell carcinoma.