PriMera Scientific Medicine and Public Health (ISSN: 2833-5627)

Case Report

Volume 7 Issue 3

Adenocarcinoma Arising from A Gastric Duplication Cyst in a Pregnant Patient: A Case Report

Jose Luis R Luzung, Azenith May H Rafanan and Katrina Jezzela M Dela Pena*

August 31, 2025

Abstract

Objective: To report a rare case of Poorly Differentiated Adenocarcinoma Arising from a Non-Communicating Gastric Duplication Cyst (GDC) in a 25-year old pregnant patient diagnosed by routine Hematoxylin-Eosin and panel of Immunohistochemistry (IHC) stains. Clinical Feature: An incidental finding of a cystic mass measuring 21.0 cm in widest dimension located superior to the uterus and within the omentum was noted on her prenatal ultrasound at 32 weeks of AOG. INTERVENTION AND OUTCOME. Exploratory laparotomy and excision done with intraoperative findings of mass closely adherent to the transverse colon and mesocolon, posterior to pancreas and first part of the duodenum with normal bilateral adnexa. Histopathologic findings of the mass show multiple cystic structures with gastric mucosa, well-circumscribed smooth muscle layer and ectopic pancreatic tissues. The malignant transformation shows undifferentiated neoplastic cells in tight clusters and immunohistochemical staining with Cytokeratin, CAM 5.2 and Carcinoembryonic Antigen shows positive reactivity. Ki-67 proliferation index is high with 30 – 40% positivity. No reactivity in the neoplastic cells with Smooth Muscle Actin, p63, Chromogranin, DOG-1, LCA, PLAP and S-100. Two weeks post-excision, patient’s condition deteriorated and eventually went to Cardiopulmonary Arrest secondary to Multiorgan Failure; Malignancy Stage IV. Clinico-radiologic, histopathologic and immunohistochemical findings is consistent with a Poorly Differentiated Adenocarcinoma Arising from a Non-Communicating Gastric Duplication Cyst.

Conclusion: GDC is a rare malformation with malignant transformation arising from it is extremely rare. Non-specific clinical presentation may not lead to a prompt diagnosis, especially in the patient where symptoms was masked by pregnancy. A high index of suspicion coupled with radiologic, histopathology correlation, with the aid of immunohistochemistry is important for early diagnosis and treatment.

Keywords: Gastric Duplication Cyst; Malignant Transformation; Poorly Differentiated Adenocarcinoma; Immunohistochemistry (IHC) stains

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