A 56-year old woman is admitted to the hospital with a two-day history of temperature up to 104.6 degrees, joint pain and nausea.
Her history includes a diagnosis of metastatic melanoma two years ago. She has recently been treated with six doses of an immune checkpoint inhibitor. She had her last treatment a month ago.
Initial laboratory results at the hospital show:
Hemoglobin level = 9.7 g/dL
Low normal reticulocyte = 0.6%
Thrombocytopenia = 101 × 103/microL
Significant elevation in ferritin = > 40,000.00 ng/mL
Extremely high lactate dehydrogenase = 2762 U/L
Hypertriglyceridemia = 309 mg/dL
A CT scan revealed slightly enlarged, but still normal-sized spleen. A study of natural killer (NK) cells showed decreased function of the patient’s NK cells.
What are the possible diagnoses?
What additional tests would you order for a differential diagnosis?