Multiphasic CT findings of gastric adenosquamous carcinoma with prominent necrosis: A case report

Gastric adenosquamous carcinoma is a rare primary gastric malignancy composed of both adenocarcinoma and squamous cell carcinoma components. Published descriptions of its imaging features remain limited, and its appearance may overlap with that of other gastric tumors. A 70-year-old man presented with a 2-month history of epigastric pain, acid regurgitation, and heartburn, accompanied by an unintentional weight loss of approximately 10 kg. Serum tumor markers were within normal limits. Multiphasic contrast-enhanced computed tomography demonstrated irregular focal thickening and an ill-defined mass along the lesser curvature of the distal stomach. The lesion showed a shaggy serosal contour, a large central low-enhancing necrotic component, mild heterogeneous arterial-phase enhancement with gradual enhancement on portal venous and delayed images, and multiple small regional lymph nodes. The patient underwent laparoscopic-assisted distal subtotal gastrectomy, partial transverse mesocolon resection, and regional lymphadenectomy. Histopathologic examination confirmed gastric adenosquamous carcinoma with extensive necrosis, comprising approximately 60% adenocarcinoma and 40% squamous cell carcinoma. The tumor invaded the full thickness of the gastric wall and demonstrated perineural and vascular invasion, with negative surgical margins and metastases in 4 of 21 regional lymph nodes. A review of the literature indicates that gastric adenosquamous carcinoma is generally aggressive and frequently presents with deep wall invasion and nodal or distant metastasis, although its imaging features remain nonspecific. This case provides a detailed multiphasic computed tomography-pathology correlation of gastric adenosquamous carcinoma; the observed imaging findings are nonspecific and should not be regarded as a characteristic diagnostic pattern. Definitive diagnosis requires histopathologic and immunohistochemical confirmation.