Malignant Extrarenal Rhabdoid Tumor in an Elderly Patient with Metastasis to the Pancreas

Abstract

Purpose: Malignant extrarenal rhabdoid tumors (MERT) are rare, aggressive soft tissue sarcomas of early childhood, that tend to be widely metastatic at diagnosis. Involvement of the gastrointestinal tract is extremely infrequent. We report the case of an elderly patient with tumor spread to the pancreas, presenting with abdominal pain. Case: 75 year old female was diagnosed with MERT this year following investigation of a solitary pulmonary nodule. Initial CT scan did not disclose any intra-abdominal pathology. Follow up PET scan three months later revealed extensive pulmonary, soft tissue and bony lesions, as well as a 3 cm mass of the pancreatic head. Biopsy of a soft tissue mass revealed immunohistochemical and cytogenetic features of MERT. The patient had recently completed radiation therapy to the lumbar spine, one week before admission. She presented with progressively severe upper abdominal pain, nausea and vomiting over the past week. There was no evidence of obstruction on imaging, and the onset was not consistent with radiation enteritis. Repeat CT scan showed increasing size of the tumor in the pancreatic head; which was considered the cause of her abdominal pain. Symptoms were controlled with supportive therapy, and the patient was discharged to follow up with oncology for initiation of chemotherapy. Discussion: Malignant rhabdoid tumors are extremely rare neoplasms, with only about fifteen cases reported annually. Occurrence in an elderly patient is highly unusual. They have described in a variety of anatomic locations, with case reports of occasional gastrointestinal involvement including the liver, pancreas, mesentery, ileum and colon. The pancreas may be the site of primary tumor, but is more frequently involved by metastatic disease. This was difficult to evaluate in our patient, since the PET scan was performed well into the disease course. The tumor has an extremely poor prognosis with five year survival rates of 15%, even with combined modality treatment regimens. Mortality associated with widely metastatic disease is significant, about 80% at one year. Hence, aggressive therapy with surgical resection when feasible, along with adjuvant chemoradiation, is recommended.