Collision Tumor in the Stomach: Tubular Gastric Adenocarcinoma With Metastatic Adrenocortical Carcinoma-A Rare Encounter on an Endoscopic Biopsy.
Palak Arora, Md Ali Osama, Rajni Yadav et al.
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Case in brief
A gastric lesion was found to contain two distinct malignancies: primary tubular gastric adenocarcinoma and metastatic adrenocortical carcinoma. The tumors met at an abrupt interface without transitional morphology, supporting a collision tumor rather than a single neoplasm with mixed differentiation. The report emphasizes that endoscopic, histopathological, and immunohistochemical assessment was needed to distinguish the two components. Recognizing the metastatic component was clinically important because it affects staging, management, and prognosis.
What made this case unusual
The collision involved a primary gastric carcinoma and metastatic adrenocortical carcinoma. Gastric metastasis from adrenocortical carcinoma is very rare, and the report states that this combination had not previously been described.
Diagnostic / clinical pearl
When a gastric lesion has discordant morphologic features, consider the possibility of a collision tumor and use histopathology and immunohistochemistry to identify distinct primary and metastatic components.
Why it matters
Correctly identifying a metastatic component, rather than classifying the lesion as solely a primary gastric cancer, can alter staging, management, and prognosis.