Progressive Multifocal Leukoencephalopathy in a Teenager with Juvenile Dermatomyositis

Introduction: Central nervous system disease is a rare complication noted in juvenile dermatomyositis and is thought to be due to both, an inflammatory and non-inflammatory injury of the blood vessels causing ischemia and end-organ damage. However, progressive multifocal leukoencephalopathy (PML) that develops due to activation of JC virus in immune-compromised states is seldom reported in children with juvenile dermatomyositis.

Case Description: A 16-year-old female with juvenile dermatomyositis presented to the emergency department with a wobbly gait, generalized weakness in her upper and lower extremities (right greater than left), and difficulty speaking for one week. Her weakness was predominantly on the right side and was progressively worsening to the point where she was dragging her right lower extremity. Her mother noticed that she was swaying while walking and her speech was “slowed”. She developed three episodes of worsening weakness in the past which were treated with high-dose steroids.
Her magnetic resonance imaging (MRI) revealed patchy asymmetric areas of T2 weighted hyperintensities in bilateral middle cerebellar peduncles, cerebellar hemispheres and pons, most pronounced in the right middle cerebellar peduncle [Figure 1]. Magnetic resonance angiogram showed the irregular beaded appearance of M2 and M3 segments of middle cerebral arteries bilaterally, right more than left side as well as posterior cerebral arteries [Figure 2]. Due to concerns of vasculitis, intravenous methylprednisolone 1000mg daily was initiated that transiently improved her symptoms. Two weeks later, she developed worsening neurological symptoms. A repeat MRI brain showed progressive worsening of right middle cerebellar lesions. Despite monthly cyclophosphamide therapy, her symptoms did not improve. Hence, a repeat CSF analysis was positive for JC virus detected by PCR (2900copies/ml). Her steroid dose was reduced and received 3 cycles of plasma exchange followed my monthly IVIG infusion. Her symptoms improved and her repeat CSF analysis detected 333 copies of JC virus after nine months

Discussion: Progressive multifocal leukoencephalopathy (PML), a serious demyelinating condition, is rarely reported in rheumatological conditions. Due to the extensive use of immune-modulatory therapies in the current era, increasing cases of PML are reported in rheumatological conditions such as systemic lupus erythematosus (SLE), rheumatoid arthritis, dermatomyositis, polymyositis, and other connective tissue diseases. The use of natalizumab and efalizumab are well-established causes of PML. However, in other specific immunosuppressive agents, it has been difficult to attributed causality due to the rarity of PML and multiple confounding factors that exist in many cases. The management of non-HIV PML mainly involves reduction of immunosuppression

Conclusion: Differentiating PML from new onset or exacerbation of CNS complications of underlying auto-immune conditions is challenging. PML should be considered in patients with unexplained subacute progressive focal and diffuse neurologic deficits, especially if their clinical or radiologic status worsens with increased intensity of immunosuppressive therapy.