Malignant Extra-renal Rhabdoid Tumor (MERT) of the Gastrointestinal Tract: A Systematic Review

Abstract

Purpose: A 61-year-old female presented to us with metastatic Malignant Extra-renal Rhabdoid Tumor (MERT) of the gastrointestinal tract, which prompted us to conduct a systematic review of the literature. MERT is a rare entity that carries a poor prognosis due to its features of early metastasis and rapid growth. Methods: A systematic search and review of the literature was performed (1966-2013) utilizing MED-LINE (Pubmed), Cochrane Library, and a review of references within review articles. The search was not restricted by date or language. Only cases of rhabdoid tumor of the gastrointestinal tract in adults were included. Results: Our search resulted 19 published cases of MERT of the gastrointestinal tract reported between 1993 to 2005: seven gastric, five esophageal, four small intestinal and three colonic. The mean age of presentation was 63 years (range 52-84). The gender distribution was 74% male (14/19) and 26% female (5/19). The mean tumor size as measured on post-operative pathology was 8.8 cm (range 3.8 cm-16 cm). On gross examination, MERT can appear fungating or ulcerated with hemorrhagic necrosis. The characteristic histology of rhabdoid tumor reveals large, poorly cohesive cells with vesicular chromatin, eccentric nuclei with prominent nucleoli, and dense eosinophilic cytoplasmic inclusions. Immunohistochemical (IHC) staining was used in 100% (19/19) of patients to confirm a diagnosis. MERT stains positive for vimentin and cytokeratin- although other epithelial markers such as Neuron Specific Enolase (NSE) and Epithelial Membrane Antigen (EMA) can also be utilized. In our review, 100% of (19/19) tumors were positive for vimentin, 95% (18/19) were positive for cytokeratin or EMA, and 5% (1/19) were positive for NSE. Forty-seven percent (9/19) of patients had local lymph node metastases and 53% (10/19) had distant metastases at presentation. Eighty-four percent (16/19) of patients had a surgical resection, 5% (1/19) underwent radiation therapy and 5% (1/19) underwent chemotherapy. Sixteen percent (3/19) either died before treatment could be initiated or had no treatment information available. Sixty-eight percent (13/19) of patients died within 1 year of diagnosis, and 16% (3/19) were alive at 1-year follow up. Follow up information was not available for 16% (3/19) of patients. The mainstay of treatment remains surgical resection with limited literature on the use of chemotherapy or radiation therapy. Conclusion: MERT is a rare entity that carries a poor prognosis with a high mortality rate. As such, it is an important entity to consider as it requires IHC staining to confirm the diagnosis.