Melanocitoma y melanomatosis meníngea, lesiones similares pero diferentes

Meningeal melanomatosis is an extra-axial well-encapsulated malignant tumour with diffuse meningeal growth and dark coloration (due to high melanin contents), while meningeal melanocytoma is the focalized benign variant. Melanocytic lesions may be secondary to melanoma or be histologically benign, however, their diffuse nature makes them impossible to cure. Melanocytosis is a diffuse tumour that can form solitary extra-axial tumours, which invades the parenchyma and presents signs of malignancy with increased mitosis and Ki67, observed in 1 to 6% of immunopathological exams. Melanoma of the leptomeninges, presents signs of malignancy with anaplastic cells, which cluster in fascicles of melanin in the cytoplasm, with more than 3 atypical mitoses per field and Ki67 presenting in more than 6% of the immunopathological fields analysed.