Masquerading Meckelʼs? Gastrointestinal PEComa Causing Hematochezia in 9-Year-Old Girl

Abstract

Background: Perivascular endothelial cell neoplasms (PEComas) are rare mesenchymal tumors that occur in variety of anatomic locations including abdominopelvic and retroperitoneal sites, visceral organs and soft tissues of extremities, skin and bones. Coined in 1996, PEComas are smooth muscle and melanocytic marker positive (smooth muscle actin, HMB45, Melan-A, MiTF) and are part of a family of tumors which include angiomyolipomas, lymphangioleiomyomatosis, clear cell “sugar” tumor of the lung, extrapulmonary clear cell “sugar” tumor, and clear cell myomelanocytic tumor. Most recent reviews estimate pediatric PEComa cases involving the GI tract to be under 20. Due to their relative rarity, no formal system currently exists regarding classification, associated prognostic factors, and treatment. Case: A 9 year old previously healthy female presented with 2 episodes of hematochezia. Her hemoglobin decreased from 12.7 (g/dL) to 9.5 in the first 35 hours then down to 6.9 in the following 24 hours. Presentation of massive painless rectal bleeding with currant jelly stools appeared classic for Meckel's diverticulum and patient was taken to the OR without Meckel's scan. Surgical evaluation did not note the presence of a diverticulum; appendix was removed per parents request. Patient hemoglobin continued downtrending post-operation and tagged red blood cell scan was performed, revealing physiologic distribution of tracer and no abnormal radiotracer pooling consistent with no active gastrointestinal bleeding. Decision was made for an esophagogastroduodenoscopy and colonoscopy; colonoscopy revealed a 2.5 cm multilobulated polyp at the hepatic flexure. Location of the polyp was tattooed endoscopically and later removed surgically. Histopathology was consistent with PEComa with no features of malignancy, confirmed from several independent histopathology labs. Although patient's PEComa showed no features of malignancy the margins were not clear; a repeat colonoscopy was performed 6 months postresection did not reveal recurrence of the lesion and her hemoglobin has since been stable. Conclusion: Although rare in presentation, diagnosis of gastrointestinal PEComa should be entertained in cases of hematochezia without an obvious source of bleeding. Patients with a negative Meckel's scan or seemingly atypical presentation of a Meckel's diverticulum may warrant additional workup.