Diagnosis of meningeal melanomatosis in a dog using magnetic resonance imaging and cerebrospinal fluid findings

Abstract

A 13-year-old spayed female Labrador Retriever was presented with severe progressive tetraparesis. The neuroanatomic localization was the C1-C5 spinal cord segments with brainstem or cranial nerve involvement. Magnetic resonance imaging revealed diffuse T1weighted and T2-weighted hyperintense lesions with strong contrast enhancement spreading through meninges of the cervical spinal cord and the brain. Few small round areas showing T1weighted hyperintensity and T2-weighted hypointensity were scattered within the lesions. Cerebrospinal fluid analysis revealed neoplastic round cells and possible melanocytes. Malignant melanoma was suspected. At necropsy, the brain and the entire spinal cord were covered with thick, dark membranous tissue. Based on histopathologic findings, a positive response against Melan-A, and no melanoma identified outside the central nervous system, primary meningeal melanomatosis was diagnosed.

Case report: MRI and CT imaging features of a melanocytic tumour affecting a cervical vertebra in an adult dog, and review of differential diagnosis for T1W-hyperintense lesions

“…An example of this includes a recent case of an extradural melanoma affecting a thoracic vertebra in a dog, where the lesion was hyperintense on both T1W and T2W images (7). Similarly, a case of meningeal melanomatosis characterised by T1W hyperintensity and T2W hyperintensity with a few small areas demostrating T2W hypointensity has also been described in the literature (8). The cause of these atypical MRI findings is not completely understood.…”

Computed Tomographic and Magnetic Resonance Imaging Features of Oral Melanoma in a Dog

“…The MRI findings of the meningeal melanomatosis generally showed hyperintensity on the T1-and T2-weighted images and hypointense spots on the T2-weighted image in a few small areas (20). On post-contrast T1-weighted images, the lesion was strongly enhanced (20).…”

“…In the case of uveal melanocytoma, the lesion showed hyperintensity on the T1-weighted image and hypointensity on the T2-weighted image (21). The MRI findings of the meningeal melanomatosis generally showed hyperintensity on the T1-and T2-weighted images and hypointense spots on the T2-weighted image in a few small areas (20). On post-contrast T1-weighted images, the lesion was strongly enhanced (20).…”