To report a rare case of metastatic pancreatic adenocarcinoma presenting as a calcified, ring-enhancing brain mass with cystic features, highlighting atypical imaging findings and diagnostic challenges.

Pancreatic adenocarcinoma (PA) is a highly lethal malignancy with a poor prognosis, with less than 1% of cases exhibiting brain metastases. Typically, PA metastasizes to the liver, lungs, and peritoneum. The rarity of CNS involvement is due to factors such as the metastatic pattern favoring liver spread via the portal vein and the protective blood-brain barrier. Brain metastases from PA are associated with poor outcomes, with median survival of 2-6 months post-diagnosis. Imaging usually reveals ring-enhancing lesions with surrounding edema, while calcification in brain metastases is particularly rare, complicating diagnosis.

A 44-year-old African-American female with a BRCA1 mutation and stage IV pancreatic adenocarcinoma presented with new-onset left-sided weakness and multiple falls. She was undergoing palliative chemotherapy for hepatic and pulmonary metastases. Neurological examination revealed significant left-sided weakness with foot drop. MRI of the brain showed a 3.4 x 2.7 x 2.9 cm partially cystic and solid mass in the corpus callosum with irregular ring enhancement and internal calcification, consistent with metastatic disease. Differential diagnoses included primary brain tumors such as gliomas, metastases from more common cancers, and infectious lesions. A biopsy confirmed adenocarcinoma of pancreatic origin, with tumor cells positive for CA19-9 and CDX2. Despite the atypical calcification and unusual imaging, findings were consistent with metastatic PA. Unfortunately, the patient was lost to follow-up after the biopsy.

This case highlights a rare and atypical presentation of brain metastasis from PA, featuring calcified, ring-enhancing lesions rarely seen in this context. The patient's BRCA1 status may have influenced her cancer's metastatic behavior, underscoring the need for heightened awareness of such atypical presentations in pancreatic cancer patients with CNS symptoms.