Discussion
UPS is a diagnosis of exclusion reserved for sarcomas with a distinct combination of immunohistochemical and microscopic features, made only after careful consideration of other differential diagnoses. This case is unique both for being localized to the gastrointestinal tract, with only 14 cases reported of cecal or ascending colon UPS, as well as the young age of the patient. Only 2 other cases of gastrointestinal UPS have been reported in the pediatric population12, 13.
This patient developed a non-obstructing right sided colonic mass, with systemic features of disease including elevated inflammatory markers, anemia, and weight loss, which are consistent with the presentation of UPS. In spite of the tumor’s large size at diagnosis (7cm), the tumor was excised with clear margins, no positive lymph nodes, and no signs of metastasis. A lung lesion that was initially suspicious was resected and found to be Histoplasmosis.
Chemotherapy was not given in this case as the tumor was resected with clear margins and there was no lymph node involvement or metastatic disease. She will be followed by oncology to monitor for recurrence through periodic imaging and labs. Additional research into the role of radiation and chemotherapy for abdominal UPS is needed, especially for cases where surgical resection is not possible. Continued monitoring and close follow-up are essential to a good long term outcome due to a relatively high recurrence rate.
Conflict of Interest statement: no conflicts of interest reported.