General characteristics

Melanocytic lesions are diffuse or circumscribed, benign, or malignant tumors arising from melanocytes of the leptomeninges (Jellinger et al. 2000).

They include:

  • diffuse melanocytosis (diffuse melanosis) and
  • neurocutaneous melanosis,
  • melanocytoma,
  • malignant melanoma. Intermediate or mixed cases may occur.

Imaging and Location

Melanocytoma accounts for 0.06–0.1% of brain tumors; the other melanocytic lesions are rarer. These lesions typically occur in the fifth decade of life with a femaleto-male ratio of 2:1. Diffuse melanocytosis involves the supratentorial and infratentorial leptomeninges; melanocytomas occur as solid masses in the cranial and spinal compartments.

On both CT and MRI, the features of melanocytic lesions are similar to those of meningiomas


  1. M.F. Reiser, W. Semmler, H. Hricak (Eds.) "Magnetic Resonance Tomography", Springer 2008