Central neurologic involvement in mycosis fungoides: ten cases, actuarial risk assessment, and predictive factors

Neurologic involvement in mycosis fungoides is rare. Isolated case reports in the literature suggest the pattern and the natural history for such occurrences, while a literature summary can provide direction on diagnosis and management. Although case series may confirm such information, cohort data are required to establish an overall risk of occurrence and to evaluate possible predictive factors.

We presented a case of central nervous system involvement in mycosis fungoides from Haifa, Israel and tabulated a series of nine cases from Canada. To estimate the risk of neurologic involvement, a cohort of 680 consecutive patients with newly diagnosed mycosis fungoides, of which the nine cases of neurologic involvement emerged during follow up, was analyzed using the Kaplan-Meier method. The actuarial risk of developing neurologic involvement was related to the baseline tumor-node-metastasis-blood classification factors.

The pattern of disease in these 10 additional cases confirms the overall pattern in the approximately 40 patients described in the literature. The main symptoms are fluctuating higher cognitive functions and cranial nerve dysfunction, with fairly rapid clinical onset of symptoms. Most cases of central neurologic involvement with mycosis fungoides emerge within a setting of advanced disease. In patients with newly diagnosed mycosis fungoides, the greatest risk of developing neurologic involvement is within the first several years after diagnosis and is associated with the initial stage of disease. Patients with two or more of the T3-4, N3, M1, and B1 classification factors have a one in six chance of developing central neurologic involvement, while there is about a one in a hundred chance for the corresponding control group.

Neurologic involvement with mycosis fungoides is indeed rare, but it is associated with a more advanced stage at diagnosis and with other visceral disease that can precede it. Although the role of low-dose prophylactic cranial radiation is uncertain, overt neurologic involvement requires urgent palliative treatment.