Researchers found evidence of the virus, human herpesvirus 6 (HHV-6) in the tissues of 25 of 35 children with Langerhans cell histiocytosis (LCH), compared to virus detected in only five of 19 children without LCH. The research team, led by John P. Dormans, M.D., director of Orthopaedic Surgery at The Children's Hospital of Philadelphia, published its findings in the January/February issue of the Journal of Pediatric Orthopaedics.

Langerhans cells, found in the blood, play an active role in the immune system. An uncontrolled excess of Langerhans cells leads to LCH, with effects that range from a limited, spontaneously resolving illness to a chronic, life-threatening disease involving multiple organ systems. Although rare, occurring in approximately five children per million, LCH most commonly strikes bone, causing painful lesions or fractures.

"LCH is called the 'great imitator' because it resembles particular bone cancers," said Dr. Dormans. "Fortunately, most children survive the disease these days." Most bone lesions resolve on their own without treatment. In other cases, surgeons successfully treat the disease by removing the abnormal area of bone.

However, successful treatment may elude physicians when LCH is chronic and affects multiple systems. Chemotherapy may succeed, at least temporarily, but only for 50 to 60 percent of patients. The cause of LCH remains unknown, and the Children's Hospital researchers investigated its origins, with the goal of advancing treatments.

"It's important to define whether LCH is primarily a tumor-like process or a reactive process, that is, one in which the immune system reacts to an infection or other insult," said M
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Contact: Joey Marie McCool
McCool@email.chop.edu
267-426-6070
Children's Hospital of Philadelphia
8-Mar-2004