Since we’re apparently going to ignore the opthalmologists and LP everyone anyway…
Study design: CSF samples were obtained from 7 patients with VKH as well as controls with PD, motor neuron disease, viral and bacterial meningitis and HSV encephalitis, for cytology and immunocytochemistry.
Results: samples from 6 of 7 patients with VKH, but not controls, had macrophages with basophilic granules in their cytoplasm, and these cells were recognized by a monoclonal mouse ab to human melanoma cells. But, these cells were very rare (4-5 per 10k CSF cells).
So, it would probably be a bit tedious to look for these melanin-staining cells for diagnostic purposes. On the other hand, that’s why I didn’t go into path, so maybe it just requires the proper motivation.
Bonus fun fact: why are there melanocytes in the meninges, anyway? They appear to scavenge dangerous free radicals away from the brain. They’re mostly located over the ventrolateral pons and medulla.