Pineal Gland Metastasis from Gallbladder Adenocarcinoma with Leptomeningeal Dissemination: A Rare Radiological Presentation

Background: Metastatic lesions of the pineal gland are rare and account for a small percentage of intracranial secondary tumors. The most common primary sources include lung and breast carcinoma. Metastasis from gallbladder adenocarcinoma to the pineal region is exceptionally uncommon. When associated with leptomeningeal dissemination, it reflects advanced systemic spread and carries a poor prognosis. Case Presentation: A 64-year-old male with a history of moderately differentiated gallbladder adenocarcinoma presented with diplopia, dizziness, upper limb paresthesias, and progressive weakness. MRI brain with contrast revealed a well-defined 10 × 10 mm homogeneously enhancing pineal mass (Figure 1A and 1B) with associated cerebellar folial and upper cervical leptomeningeal enhancement (Figure 1C). MR spectroscopy demonstrated elevated choline and reduced N-acetylaspartate peaks, supporting a malignant neoplasm (Figure 1D). No obstructive hydrocephalus was observed. Based on imaging characteristics and oncologic history, pineal metastasis with leptomeningeal carcinomatosis was strongly suspected. Conclusion: Enhancing pineal lesions in elderly patients with known malignancy should raise suspicion for metastatic disease, particularly when accompanied by leptomeningeal enhancement. MR spectroscopy provides supportive metabolic evidence of malignancy. Early recognition of this rare metastatic pattern is essential for appropriate oncologic management.