Diagnosis and management of high risk gastrointestinal stromal tumor in first trimester pregnancy: A case report and review of the literature.

Objective: There are less than 20 reported cases of gastrointestinal stromal tumors in pregnancy. Of these reported cases, there are only two that detail GIST in the first trimester. We report our experience with the third known GIST diagnosis in the first trimester of pregnancy. Notably, our case report highlights the earliest known gestational age at time of GIST diagnosis. Methods: We conducted a literature review of GIST diagnosis in pregnancy via PUBMED, using a combination of the following terms: (pregnancy or gestation) and (GIST). We utilized Epic for chart review of our patient's case report. Results: A 24 year old G3P1011 presented to the Emergency Department at 4w6d by last menstrual period (LMP) with worsening abdominal cramping, bloating, and associated nausea. Physical exam revealed a large, mobile, nontender mass palpated in the right lower abdomen. Transvagianl ultrasound noted the presence of a large pelvic mass of unknown etiology. Pelvic magnetic resonance imaging (MRI) was obtained for further characterization, revealing a 7.3× 12.4 × 12.2 cm mass with multiple fluid levels, centered in the anterior mesentery. Exploratory laparotomy was performed with en bloc resection of small bowel and pelvic mass, with pathology demonstrating a 12.8 cm spindle cell neoplasm compatible with GIST and notable for a mitotic rate of 40 mitoses/50 high power field (HPF). Next generation sequencing (NGS) was pursued in order to predict tumor responsiveness to Imatinib, which revealed a mutation at KIT exon 11, suggesting a response to tyrosine kinase inhibitor therapy. The patient's multidisciplinary treatment team, consisting of medical oncologists, surgical oncologists, and maternal fetal medicine specialists, made the recommendation for adjuvant Imatinib therapy. The patient was offered termination of pregnancy with immediate initiation of Imatinib, as well as continuation of pregnancy with either immediate or delayed treatment. Interdisciplinary counseling focused on both the maternal and fetal implications of each proposed management plan. She ultimately elected termination of pregnancy, and underwent an uncomplicated dilation and evacuation. Conclusions: GIST diagnosis in pregnancy is exceedingly rare. Patients with high-grade disease encounter a multitude of decision-making dilemmas, often with competing maternal and fetal interests. As additional cases of GIST in pregnancy are added to the literature, clinicians will be able to implement evidence-based options counseling for their patients. Shared decision-making is contingent upon patient understanding of diagnosis, risk of recurrence, available treatment options, and the treatment-related implications on maternal and fetal outcomes. A multidisciplinary approach is crucial for optimization of patient-centered care.