Background: Undifferentiated pleomorphic sarcoma (UPS) is a high-grade neoplasm typically diagnosed in older adults and localized to the extremities or retroperitoneum. Because of poor response to therapy and high rates of recurrence, this neoplasm is associated with a poor prognosis. Case Report: A 12-year-old female presented with weight loss, abdominal pain, fatigue, and diarrhea. She was profoundly anemic with occult blood-positive stools. On endoscopy, a fungating cecal mass was biopsied and diagnosed as malignant sarcomatoid neoplasm. The neoplasm was resected with clear margins during subsequent surgery, and on final pathology was diagnosed as UPS. A suspicious lung nodule was also removed via video-assisted thoracoscopic surgery and found to be a granuloma positive for Histoplasma capsulatum for which the patient received antifungal therapy. The patient did not receive additional chemotherapy or radiotherapy and was doing well without signs of recurrence at 12 months postresection. Conclusion: This report of cecal UPS in a 12-year-old is rare because of the patient's age and tumor location. We have identified only 2 other case reports of pediatric gastrointestinal UPS. This case illustrates the need for a broad differential and prompt workup in pediatric patients presenting with weight loss and abdominal complaints. More information regarding the management and outcomes in cases of gastrointestinal UPS is needed to assist providers in determining the best treatment course and to allow for better prognostication.