MS-like presentations of HTLV-1 infection: Case-series and review of literature.

INTRODUCTION: Human T-lymphotropic virus type 1 (HTLV-1), was the first human retrovirus to be discovered in 1980. The majority of HTLV-1 infected individuals (95%) will remain asymptomatic for their lifelong; whereas 5% of these patients will be symptomatic, mainly hematologic and neurologic.

CASE REPORT: We present four patients with HTLV-1 infection (from Mashhad and Neyshabur cities in Khorasan province in the northeast of Iran as an endemic region) who were referred with MS-like clinical picture associated with some hyperintense lesions in brain MRI.

DISCUSSION: Multiple disorders including HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other infrequent neurological complications such as polyneuropathy, amyotrophic lateral sclerosis (ALS) like syndrome, cerebellar ataxia, cranial neuropathy, dementia, myositis and MS-like presentation have been related to this virus. The latter is reported rarely. One of the probable etiologic factors in MS is HTLV1. However, this neurotropic virus produces a chronic inflammatory myelopathy similar to primary progressive MS (PPMS). In addition, a degenerative phase quite reminiscent of MS comes after inflammatory phase of HAM/TSP. Therefore, it is sometimes misdiagnosed as MS. Magnetic resonance imaging (MRI) of the brain and spinal cord is usually normal, but may occasionally show hyperintense signal abnormalities on T2-wheighted images and atropthy of the spinal cord in late disease. The patterns of signal enhancement in HAM/TSP tend to be diffuse, in contrast to discrete or multifocal abnormalities seen in MS. Like our patients, periventricular white matter lesions may also be seen. In patients with suspected MS, one should always keep in mind the other conditions that may have similar clinical and radiological presentations; hence, it is better to call it "MS syndrome" rather than "MS disease".

CONCLUSION: This article argues about similar presentations between HTLV-1 infection and MS, not mentioned before. Occasionally, HTLV-1 infection is misdiagnosed as MS and it should be considered in the differential diagnosis of patients supposed to have MS, especially in endemic areas. In other words, as MS is a diagnosis of exclusion, it is quite reasonable to do a routine HTLV-1 serological study (ELISA) for all suspected MS patients in endemic areas.