Pachymeningeal en plaque metastasis from gastric cancer mimicking subdural hematoma: illustrative case

BACKGROUND: Pachymeningeal metastasis associated with gastric cancer, especially in its early stages, is extremely rare. OBSERVATIONS: The authors describe a 77-year-old man with a past medical history of lung cancer and previously treated chronic subdural hematoma who was admitted to their hospital because of hematemesis and newly diagnosed gastric cancer. He became unconscious during the hospitalization. The preoperative brain imaging studies had the appearance of recurrent subdural hematoma and extracranial tumor with skull invasion. Craniotomy revealed pachymeningeal carcinomatosis and en plaque metastasis of tumor. The histopathology of the tumors was consistent with metastatic gastric adenocarcinoma. LESSONS: This is the first reported case of metastatic gastric cancer as a pachymeninges-based en plaque entity. This report highlights the rare radiological presentation and operative findings in this case. The authors also summarize those case reports associated with dural metastasis arising from gastric cancer.