Acute abdomen with a parasitic smooth muscle tumor of uncertain malignant potential (STUMP) in pregnancy; a unique case report

Introduction and importance: Diagnosis of a smooth muscle tumor of uncertain malignant potential (STUMP) during pregnancy is rare. Furthermore; the investigation of an intra-abdominal mass during pregnancy is clinically challenging due to anatomical changes and additional considerations of the developing fetus and radiation exposure. The unusual nature and diagnostic dilemma of such a case warrants a case report to serve as an educational prompt to clinicians who may encounter pregnant patients with undifferentiated intra-abdominal masses and/or suspecting of STUMP.Case presentation: We report a rare case of a parasitic STUMP diagnosed during pregnancy. The patient presented with a new umbilical hernia and deranged liver function tests (LFT's) during her third trimester. MRI reported a large mass in the left mid flank with intra-abdominal varices extending into the umbilical hernia. She went on to develop an acute abdomen requiring laparotomy where a parasitic fibroid adherent to the omentum was excised and a preterm infant was delivered via caesarean section. Histology was difficult due to pregnancy related changes but ultimately confirmed a diagnosis of STUMP.Clinical discussion: STUMP in pregnancy is rare and diagnosis is further complicated by histological challenges due to pregnancy related changes. Postoperative diagnosis is challenging due to lack of universally accepted diagnostic criteria and Uncertainty regarding prognostic factors makes management and follow-up of patients with STUMP challenging. Studies have shown that younger patients are more likely to demonstrate recurrence. Conclusion: Investigation and management of intra-abdominal masses in pregnancy is challenging. It requires timely multi-disciplinary team (MDT) input. Additional complications and considerations relate to the preterm fetus. Knowledge and understanding of these difficulties will better equip clinicians working with such patients to formulate a structured and well informed approach to the pregnant patient with a new intra-abdominal mass. Diagnosis of STUMP during pregnancy may be challenging for the pathologist and require further exert opinion.