Case ReportRapid progression of a pregnancy-associated intra-abdominal desmoid tumor in the post-partum period: A case report

•Desmoid tumors are rare neoplasms with unpredictable clinical behavior.•Intra-abdominal desmoid tumors are uncommon in pregnancy.•Spontaneous regression of pregnancy-associated desmoid tumors may occur post-partum.•Desmoid tumors may be initially managed with observation alone.•Surgical resection may be required for large, symptomatic tumors.

IntroductionThe clinical behavior of desmoid tumors can be unpredictable, particularly when they arise in the ante-partum or post-partum period. We present a case of an intra-abdominal desmoid tumor that was identified in the ante-partum period, progressed rapidly in the post-partum period, and was subsequently resected.Presentation of caseThe patient is a 19 year-old female who was found to have a 12 cm intra-abdominal mass on a fetal assessment ultrasound. The decision was made to observe the patient and monitor the mass for growth. However, the mass rapidly grew in the post-partum period. The patient was transferred to our institution after an exploratory laparotomy revealed a large intra-abdominal mass emanating from the small bowel mesentery. The 30 cm × 24 cm × 16 cm mass was successfully resected with negative margins, and the pathologic diagnosis of desmoid tumor was confirmed. The patient had an uncomplicated post-operative course and was discharged on post-operative day 6.DiscussionThe majority of pregnancy-associated desmoid tumors are in the abdominal wall, arising from the rectus abdominus muscle or from previous Cesarean section scars. These tumors may spontaneously regress in the post-partum period and therefore, patients with these tumors are often observed. Close follow-up is important so that rapid tumor progression, which may lead to unresectability, can be identified and managed appropriately.ConclusionA patient with a rare case of a giant pregnancy-associated, intra-abdominal desmoid tumor that rapidly progressed in the post-partum period and was successfully treated with surgical resection with negative margins.