Hemophagocytic lymphohistiocytosis (HLH)

Disease information

Overview
Causes
& Symptoms
Treatment

Overview

Hemophagocytic lymphohistiocytosis (HLH) is a rare but serious medical condition where the body's defense system, the immune system, doesn't work the way it should. Normally, part of this defense system includes natural killer (NK) cells and T-lymphocytes, which are like soldiers that attack and destroy invaders like germs. In HLH, these cells are confused and can't stop the invaders, which causes a chain reaction leading to intense inflammation throughout the body. This inflammation can cause very high fevers, and it can also cause a type of white blood cell called a macrophage to start consuming other blood cells, including other white blood cells, red blood cells that carry oxygen, and platelets that help stop bleeding. This can lead to a drop in these blood cells, making patients more prone to infections, feeling tired and weak, and bleeding more easily than usual.

Causes & Symptoms

Viruses the most common cause, especially Epstein-Barr Virus (EBV), other herpesviruses, and numerous other unidentified types of viruses
Bacterial and fungal infections
During active phases of autoimmune diseases or concurrent with infections
Hematological and solid neoplasms
Cause unknown approximately 25%

Treatment

▲ Treatment phases
(HLH-2004 protocol)

The treatment plan we're discussing was first designed for kids, but now it's being closely looked at for adults too, in a special kind of study called a prospective study. This approach mainly uses steroids, which are strong medicines that help reduce swelling and calm down the immune system, and drugs like cyclosporine that help slow down an overactive immune system. For milder cases, these medicines might be enough. But if the disease starts to get worse quickly, doctors will often use a cancer-fighting drug called etoposide (EPS). EPS is really good at calming down T-cells, a type of cell in the immune system that can go into overdrive. If the disease keeps getting worse or comes back after about two months of chemotherapy, doctors might recommend a treatment called hematopoietic stem cell transplantation. This procedure can help reset the immune system and get it back to working the way it should.