Table 2.

Variables that can help differentiate between PID and SID in patients with hematological malignancy.

Item	PID	SID
Recurrent/severe infections, autoimmune diseases, enteropathy	Past medical history Family history	After cancer and/or cancer therapy, other causes
Immunological variables at lymphoma diagnosis	Low IgG/IgA ( <2SD) Low levels of natural antibodies Low antibody responses at cancer diagnosis (primary and secondary responses) Very low serum free kappa/lambda (specific for CVID) Defect in memory B-cell phenotype	Normal/low secondary responses
B-cell reconstitution after therapy	No	Rare but possible
Response to cancer therapy	Toxicity, infections, second primary cancer, cancer recurrence
Genetic studies	Germline mutations associated with lymphoma/PID
Preventive strategies	Active surveillance of other complications (clinical, imaging, endoscopy), choice of cancer immunotherapy, PCR/IH search for oncogenic viruses in blood or tissues

CVID, common variable immune deficiency; IH, immunohistochemistry; PCR, polymerase chain reaction; PID, primary immunodeficiency; SID, secondary immunodeficiency.