Table 1

Diagnosis of HLH; diagnostic criteria and laboratory results of cases

(A) The diagnosis of HLH can be established if criterion 1 or 2 is fulfilled
A molecular diagnosis consistent with HLH
Diagnostic criteria for HLH fulfilled (5 of 8 criteria below)
 Cytopaenias (affecting >2 of 3 lineages in peripheral blood)
 Haemoglobin <9.0 g/dL, platelets <100×109/L, neutrophils <100×109/L
 Hypertriglyceridaemia and/or hypofibrinogenaemia
 Fasting triglycerides ≥3.0 mmol/L, fibrinogen <1.5 g/L
 Haemophagocytosis in bone marrow or spleen or lymph nodes. No evidence of malignancy
 Low or no natural killer (NK) cell activity
 Ferritin ≥500 µg/L
 sCD25 (soluble interleukin (IL)-2 receptor) ≥2400 U/mL
(B) Clinical and laboratory featuresCase 1Case 2Case 3
Time to onset symptoms post vaccination (days)578
Temperature (38.4–39.4°C)39.339.241.2
OrganomegalyYes (hepatomegaly)NoYes (splenomegaly)
Haemoglobin (Normal range (NR) 120–150 g/L)10.111.910.5
Platelets (NR 150–400 x 10×9/L)5469319
Ferritin (NR 15–400 µg/L)159 076552958 255
Lactate dehydrogenase (LDH) (NR 90–275 iU/L)5361178541
Triglyceride (NR 0.5–2.3 mmol/L)6.322.7
Fibrinogen (NR 2.12–4.88 g/L)0.70.944.17
Alanine aminotransferase (ALT) (NR 0–35 iu/L)13247
Troponin (NR <14 ng/L)29931242
Haemophagocytosis on bone marrow biopsyYesYesYes*
sCD25 (0–2500 pg/mL)483392323575*
HScore for HLH (% probability)259 (>99)220 (96)219 (96)
  • (A) HLH-2004 diagnostic. (B) Laboratory results of cases 1–3 at time of diagnosis.

  • *In case 3, undertaken after 3 days of methylprednisolone.

  • HLH, haemophagocytic lymphohistiocytosis.