What is the Difference Between HLH and MAS?
🆚 Go to Comparative Table 🆚Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are two distinct but overlapping syndromes characterized by disorganization and malfunction of the immune system. They share similar clinical manifestations, such as marked hyperferritinemia, cyclic fevers, cytopenias, hepatosplenomegaly, and coagulopathy. The main differences between HLH and MAS are their associations and triggers:
- HLH: Typically associated with viral infections, malignancy, and certain chemotherapies. It can be divided into primary (familial) or secondary (triggered by other diseases) HLH.
- MAS: Classically associated with rheumatologic conditions such as systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) [1, 2]. MAS is considered a subset of secondary HLH, which is associated with autoimmune diseases.
Both HLH and MAS are life-threatening conditions, and early diagnosis is crucial for appropriate treatment. The clinical features of MAS may include persistent high-grade fever, hepatosplenomegaly, lymphadenopathy, hemorrhagic manifestations, and a sepsis-like condition. Diagnostic criteria have been proposed for HLH and MAS in various autoimmune diseases, and selecting the proper diagnostic criteria is essential for accurate diagnosis.
Comparative Table: HLH vs MAS
Hemophagocytic lymphohistiocytosis (HLH) and Macrophage Activation Syndrome (MAS) are both disorders characterized by excessive inflammation. While they share some similarities, there are key differences between the two. Here is a table summarizing the differences between HLH and MAS:
| Feature | HLH | MAS |
|---|---|---|
| Definition | A syndrome of excessive and maladaptive inflammation | A life-threatening complication of autoinflammatory disorders, such as systemic juvenile idiopathic arthritis (sJIA) |
| Diagnosis | Diagnosed using the HLH-2004 criteria or the H-score | Diagnosed using the MAS/HLH score or the sJIA-MAS classification criteria |
| Inheritance | Can be primary (genetic) or secondary (acquired) | Generally secondary, developing in the context of rheumatological diseases |
| Mutations | HLH is often associated with mutations in genes related to cytotoxic activity of CD8 and NK cells | MAS is not typically associated with these mutations |
| Affected Age Groups | Can occur at any age, with primary HLH most frequently encountered in children | Most frequently reported in the context of sJIA, which typically affects children |
| Treatment | Treatment for HLH often involves immunotherapy, steroids, and, in some cases, stem cell transplantation | Treatment for MAS is focused on controlling inflammation and may include medications such as anakinra, canakinumab, or tocilizumab |
It is important to note that the diagnosis of both HLH and MAS can be challenging, as there are no pathognomonic characteristics that define these disorders. Additionally, some researchers suggest that MAS, secondary HLH (sHLH), and familial HLH may be considered as members of a disease spectrum due to the similarities in their clinical manifestations.