Hemophagocytic lymphohistiocytosis D76.1

The hemophagocytic lymphohistiocytosis (HLH) family encompasses a spectrum of acquired (secondary) and also congenital (primary) life-threatening hyperinflammatory syndromes.

• Primary congenital or familial HLH is a genetically heterogeneous, hereditary, autosomal recessive, hyperinflammatory syndrome caused by a massively exuberant, sepsis-like, inflammatory response of the immune system with overwhelming activation of T lymphocytes and macrophages. It is based on mutations in genes leading to a disruption of the cytolytic function of NK and T cells. The disease is life threatening.
• Secondary, acquired HLH is a reactive, massively exuberant, sepsis-like, inflammatory reaction of the immune system triggered by different initiators. Causes include various bacterial, viral or mycotic infections. Furthermore, hematopoietic neoplasms of various origins. Cytomegalovirus, Epstein-Barr virus, HIV and COVID-19 are the most common triggers. Autoimmune diseases such as juvenile rheumatoid arthritis or systemic lupus erythematosus can also trigger this hyperinflammatory response.

The clinical picture often hardly differs from sepsis, SIRS or severe infection and is protracted. Often occurring in combination with primary immunodeficiency diseases (see below Immunodeficiencies Primary (Overview and Classification)