P2.K220: Constipation in a Three Year Old: Common Symptom, Uncommon Disease

Introduction: Constipation is a common chief complaint among children. Outside of the neonatal period, constipation in children is typically functional. Some red flag symptoms that prompt further workup include failure to thrive, severe abdominal distension, vomiting, and fever. Rhabdomyosarcoma is a common soft tissue malignancy found in the pediatric population. Embryonal rhabdomyosarcoma frequently presents in the head and neck region and genito-urinary tract, whereas alveolar rhabdomyosarcoma often presents in the extremities and trunk. The presenting symptoms are variable and contingent upon the location of the mass. We present a case of a three-year-old who presented to the emergency department with constipation and was subsequently found to have abdominal embryonal rhabdomyosarcoma.

Case Description: A 3-year-old female with no past medical history presented to the emergency department with four days of constipation, subjective fevers, three days of abdominal distension and one day of loss of appetite. The symptoms started two weeks prior with non-radiating abdominal pain that progressively worsened. Vitals on admission were notable for fever and mild tachycardia. Exam was significant for diffuse abdominal distension with tenderness to palpation. Additionally, labs showed a microcytic anemia and leukocytosis. While admitted, the patient had persistent fevers. Abdominal US demonstrated a complex abdominal mass measuring up to 16 centimeters (Figure 1). MRI was obtained and demonstrated a large solid and cystic mass extending from lower pelvis into the upper abdomen (Figure 2). The patient then underwent ultrasound guided biopsy, which revealed a small round blue cell tumor, favoring embryonal rhabdomyosarcoma. She was determined to be Low Risk (subset 2, stage 3, clinical group II) and began treatment with four cycles of vincristine, actinomycin, and cyclophosphamide (VAC), one cycle of vincristine, ifosfamide and etoposide (VIE), with subsequent surgical resection of the abdominal mass. Pathology confirmed embryonal rhabdomyosarcoma and she underwent an additional 6 cycles of VIE, with imaging after cycle 11 demonstrating no evidence of disease.

Discussion: Constipation is an exceedingly common reason among the pediatric population for presentation to the emergency department and is associated with significant cost burden for both the hospital and patients. It is important, however, to consider key red flag signs when evaluating constipation in order to detect potential rare underlying causes such as mass effect from malignancy as in this case. In this case, the fevers and leukocytosis were key clues, suggesting a more insidious cause of this presentation, that prompted further evaluation. This case also highlights a unique presentation of embryonal rhabdomyosarcoma in the abdomen, as it is typically found in the head and neck region or the genito-urinary tract.

Conclusion: Overall, this case report presents a unique presentation of embryonal rhabdomyosarcoma within the abdomen, while underscoring the importance of working up constipation when other red flag symptoms are present.