Rare pancreatic metastasis of undifferentiated pleomorphic sarcoma originating from the pelvis: A case report

INTRODUCTION: Undifferentiated pleomorphic sarcoma (UPS) is a reclassification of malignant fibrous histiocytoma by the World Health Organization in 2002. UPS, the most common soft tissue sarcoma reported in adults, mostly recurs as lung disease. Pancreatic metastasis of UPS is extremely rare. We present a rare case of pelvic UPS with pancreatic metastasis. PRESENTATION OF CASE: A 69-year-old man was identified as having mediastinal lymphadenopathy on follow-up computed tomography (CT), 2 years after undergoing surgery for gastric adenocarcinoma (pT4aN3M0/IIIC). Subsequent positron emission tomography–CT (PET/CT) indicated pelvic lesions and magnetic resonance imaging (MRI) showed multiple tumors of the left pubis and femur. Histopathology of diagnostic thoracoscopic lymph node dissection and CT-guided needle biopsy of the left pubic lesion showed UPS. Systemic chemotherapy and targeted molecular therapy reduced multiple pelvic and metastatic tumors. Left pubic primary lesion contraction was achieved with intensity-modulated radiation therapy. CT performed 4 years after treatment initiation showed a 40-mm pancreatic head mass. Lesions other than the pancreatic tumor were in remission, and a pancreatoduodenectomy was performed. Histological analysis confirmed pancreatic metastasis of anaplastic pleomorphic sarcoma. DISCUSSION: Reports of pelvic UPS with pancreatic metastasis, as that of the present case, are extremely rare. UPS is malignant potential tumor, and complete excision is the first treatment option, while the usefulness of chemotherapy or radiation therapy remains uncertain. CONCLUSIONS: Complete resection is vital for local control in pancreatic metastasis of UPS. Sites of recurrence are rare; hence, patients must be carefully followed up.