Table 2.

Differential diagnosis table of T1 hyperintense lesions of central nervous system

	MRI	CT
Neurocutaneous melanosis	T1 hyperintensity lesions in amygdalae. Other involving sites: cerebellum and thalami. Dura is usually spared.	Usually not helpful tool in diagnosis. No calcification Hydrocephalus or Dandy-Walker malformation findings, if any.
Primary/secondary central nervous system melanoma	Melanocytic deposits in the central nervous system; if associated cutaneous lesions are malignant. T1 hyperintensity lesions in any parenchymal region. No predilection. Differentiation is difficult with NCM.	Lesions may be mild/moderate hyperdense on noncontrast images. No calcification on CT.
Leptomeningeal melanomatosis	Diffuse leptomeningeal hyperintensity is typical on precontrast T1W images. No amygdalar predilection. The parenchymal involvement is secondary and rare.	CT is usually unremarkable. No calcification. Hydrocephalus or diffuse leptomeningeal contrast enhancement may be shown if any.
Urbach–Wiethe disease (lipoid proteinosis)	Hypointense on T2W images, hypo- or hyperintense on T1W images in the amygdala, hippocampus.	Calcifications are the hallmark findings, mostly occurring in the amygdala, hippocampus, parahippocampal gyrus, striatum.