MR imaging findings in a dog with intravascular lymphoma in the brain.

Intravascular lymphoma (malignant angioendotheliomatosis, angiotrophic lymphoma) is a rare neoplastic disorder in dogs. The literature contains few reports in dogs and a single report in a cat. Intravascular lymphoma is characterized by an intravascular proliferation of malignant lymphocytes. This unique angiocentric distribution of neoplastic cells leads to the characteristic clinicopathologic feature of thromboses and infarctions. In people, intravascular lymphoma has a predilection for vessels in the central nervous system (CNS) and skin. Typically, affected patients have episodic symptoms that coincide with the timing of infarctions. This report details the clinicopathologic description and magnetic resonance (MR) images of a dog with intravascular lymphoma that resulted in multiple CNS infarctions. Abnormalities identified with MR imaging consisted of multifocal hyperintensities observed in pre-contrast T1-weighted, T2-weighted, intermediate-weighted, and FLAIR pulse sequences. Lesions were most conspicuous on the FLAIR images. In addition, there was mild enhancement of the lesions seen in post-contrast T1 weighted images.