Schwannosis in the brain of a neonatal calf.

Schwannosis is a rare, non-neoplastic, perivascular proliferation of aberrant Schwann cells within the CNS with simultaneous partial myelination of axons. A single report exists in veterinary medicine of schwannosis in the spinal cord of 3 foals and 1 calf. Here we describe a case of schwannosis in the brain of a 1-d-old Holstein-Friesian calf, submitted for autopsy due to arthrogryposis and premature death, with no other gross abnormalities observed. Histologically, the brain had multifocal, mainly perivascular, spindle-cell proliferations within the white matter of the medulla oblongata and focally within the gray matter of the midbrain. These cells immunolabeled with periaxin, myelin protein zero, SOX10, S100, and equivocally for vimentin, indicating Schwann cell origin. No changes were identified within other organs. Ancillary tests did not support an infectious etiology. Schwannosis should be considered as a differential diagnosis when investigating cases of arthrogryposis in calves with negative ancillary tests for infectious conditions.