Table 2.

HLH-2004 diagnostic criteria for the patient.

HLH-2004 diagnostic criteria	Met in patient (Y/N)	Key supporting findings in this case
1. Fever	Yes	Persistent high-grade fever (Tmax 39 °C)
2. Splenomegaly	Yes	Confirmed by imaging (CT scan)
3. Cytopenias (affecting ≥ 2 of 3 lineages): - Hemoglobin < 9.0 g/dl - Platelets < 100 × 109/L - Neutrophils < 1.0 × 109/L	Yes	Progressive decline in hemoglobin and platelets (Hemoglobin: 64 g/L, 73 g/L, 71 g/L. Platelets: 64 × 109/L, 69 × 109/L.)
4. Hypertriglyceridemia (fasting ≥ 265 mg/dl) and/or Hypofibrinogenemia (≤ 150 mg/dl)	No
5. Hemophagocytosis in bone marrow, spleen, or lymph nodes	Yes	Identified in bone marrow biopsy
6. Low or absent NK-cell activity	No
7. Ferritin ≥ 500 ng/ml	Yes	Significantly elevated (Strongly Elevated: 542.9 ng/ml, 635.0 ng/ml, 2552 ng/ml, 2772ng/ml).
8. Elevated soluble CD25 (sIL-2 receptor) ≥ 2,400 U/ml	Yes	Extremely Elevated: sIL-2R > 7720.0 IU/ml on multiple tests.

Diagnosis of hemophagocytic lymphohistiocytosis is made when at least 5 of the 8 criteria are fulfilled.