PML and myeloid sarcoma: Fig 1 illustrates typical MRS spectra found in PML lesions (Fig 1A: E-pPML, 8 months post PML diagnosis, and Fig 1B: L-pPML, 27 months post PML diagnosis); NAWM (Fig 1C, same patient as in A); and a MS lesion which was apparently not affected by the PML (Fig 1D, same patient as in B).