Fig. 1

Scoring of PML morphological features and their frequency in the samples. a PML morphological features and corresponding scores (scores of 1–3) were as follows: demyelination, enlarged oligodendroglial nuclei, bizarre astrocytes, atypical astrocytes and foamy macrophage infiltration. Demyelination was evaluated by Klüver Barrera double-staining with neurofilament immunohistochemistry. Other features were evaluated via HE staining. Arrows and arrowheads indicate representative cells. b Frequency distribution of each morphological feature score in biopsy (n = 74), autopsy (n = 42), and total samples (n = 116). A score of 0 indicates that no PML features were observed