MELANOMA OF THE ENCEPHALON.
Black pigment tumors have been found in connection with the brain and especially the meninges, varying in size from a pea to a walnut, and as a rule, secondary to similar formations elsewhere. They are most common in gray horses which have turned white, and may give rise to gradually advancing nervous disorder. Bouley and Goubaux record a case of this kind attended with general paralysis. W. Williams reports the case of an aged gray stallion with melanomata on the meninges and in the brain substance which were associated with stringhalt of old standing. Mollereau in a vertiginous horse found a pigmented sarcoma in the right hemisphere between the gray and white matter, and like an olive in size and shape. There were melanomata around the anus. (Annales de Medecine Veterinaire, 1889). So far as such have been examined they follow the usual rule in melanomata in having a sarcomatous structure.
While it is impossible to make a certain diagnosis without opening the cranium, the condition may be suspected, in gray horses, when melanotic tumors are abundant in the usual external situations (anus, vulva, tail, mammæ, sheath, lips, eyelids, etc.), and when brain symptoms set in and progress slowly in such a way as to suggest the gradual growth of a tumor.
Treatment is hopeless, since if they have invaded the brain, the tumors are likely to be multiple in the organ, and numerous and widely scattered elsewhere.