<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: All of the following are features of Hemophagocytic Lymphohistiocytosis (HLH), except:
Options:
A. Fever
B. Splenomegaly
C. Hyperferritinemia
D. Hyperfibrinogenemia
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is D: Hyperfibrinogenemia. Explanation: Hemophagocytic lymphohistiocytosis (HLH) is a reactive condition marked by cytopenias and signs and symptoms of systemic inflammation related to macrophage activation. For this reason, it is also sometimes referred to as macrophage activation syndrome. Some forms are familial and may appear early in life, even in infants, while other forms are sporadic and may affect people of any age. The common feature of all forms of HLH is systemic activation of macrophages and CD8+ cytotoxic T cells. Primary HLH (Mendelian inherited conditions leading to HLH) Defects in the cytolytic function of cytotoxic T cells and/or NK cells Defects in inflammasome regulation Secondary HLH (apparently non-Mendelian HLH) Infections (mainly viruses, such as EBV, HIV, and CMV, but also bacteria, parasites, and fungi) Malignancies (mainly malignant lymphoma) Macrophage activation syndrome in autoinflammatory or autoimmune disorders Other causes (organ or stem cell transplantation; metabolic,traumatic, iatrogenic causes; and, rarely, pregnancy)<|im_end|>
