PML is Very Rare in Lupus Save
A systematic review of the literature was done to assess the relationship between immunosuppressive therapy, adult systemic lupus erythematosus (SLE) and the onset of progressive multifocal leukoencephalopathy.
A total of 35 publications met inclusion criteria, and this included four observational studies, two large case series, and 29 case reports describing a total of 35 cases.
PML incidence rates among SLE patients based on observational studies ranged from 1.0 to 2.4 cases/100,000 person-years. A previous publication by Calabrese et al estimated the PML incidence rate to be 4 per 100,000 in lupus (and 0.4 per 100,000 in rheumatoid arthritis) compared with a background population rate of 0.2 per 100,000 (http://buff.ly/1TdvWgH).
Of the 35 SLE case reports, three cases were exposed to no immunosuppressant drugs at PML diagnosis, five cases had minimal immunosuppression, 23 cases had immunosuppression, and four cases were indeterminate.
PML appears to be very rare disease in SLE patients. There is an increased risk in SLE compared to the general population that may be attributed to immunosuppression and the underlying disease.