Leptomeningeal metastases of a well-differentiated neuroendocrine tumour: a rare entity.

A 73-year-old man, without any medical history, had presented with dark urine and pale stool without pain. Diagnostic imaging revealed a tumour in the pancreas with liver metastases. Histopathological examination showed a well-differentiated pancreatic neuroendocrine tumour. After a stable 2.5 years on everolimus, progression of the liver metastases was seen and a switch was made to chemotherapy. Three months later, he developed progressive spinal neurological symptoms. MRI of the spine and brain revealed leptomeningeal contrast-enhancing lesions. Cytopathological examination of the cerebrospinal fluid showed malignant epithelial cells compatible with well-differentiated neuroendocrine tumour. Epithelial cell-adhesion molecule-based flow cytometry of the cerebrospinal fluid confirmed the presence of epithelial tumour cells. Based on these results, the diagnosis of leptomeningeal metastases of an originally well-differentiated neuroendocrine tumour of the pancreas was made.