Primary gastric yolk tumours are extremely rare. We report a 52-year-old male who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in 2017 after having undergone a gastrectomy abroad due to a suspected poorly-differentiated adenocarcinoma. The patient subsequently returned to Oman to receive chemotherapy. However, while undergoing chemotherapy, an abdominal computed tomography scan revealed a lobulated mesenteric mass. Microscopic examination of the resected lesion confirmed a diagnosis of a yolk sac tumour. The mass was diffusely positive for α-fetoprotein (AFP) and a gastric carcinoma stain was negative. Gastrectomy slides from the patient’s previous surgery were examined retrospectively. The morphology was typical for a yolk sac tumour and was negative for epithelial markers. An AFP stain showed diffuse immunoreactivity. Thus, the patient was deemed to have had a primary gastric yolk sac tumour which had later metastasised to the mesocolon. Germ cell tumour protocols were initiated and the patient responded well to treatment.

Primary gastric yolk tumours are extremely rare. We report a 52-year-old male who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in 2017 after having undergone a gastrectomy abroad due to a suspected poorly-differentiated adenocarcinoma. The patient subsequently returned to Oman...