Hematological and rheumatological mimickers of IgG4-RD
| Disease . | PHGG . | High serum IgG4 . | IgG4-enriched LAD . | Eosinophilia . | RPF . | High CRP . | Other overlap with IgG4-RD . | Contrasting features and notes . |
|---|---|---|---|---|---|---|---|---|
| IgG4-RD—proliferative | ++++ | ++++ | ++++ | ++ | + | Rare | N/A | Skin, synovium, bone, parenchymal brain involvement rare Autoantibodies negative or weak positive |
| IgG4-RD—fibrotic | ++ | ++ | ++ | + | ++++ | Typically low, but can be high in active aortitis | N/A | Skin, synovium, parenchymal brain involvement rare Nasal/facial bones can be involved in EAF but other bones are not involved Autoantibodies negative or weak positive |
| Multicentric CD (particularly iMCD-IPL) | +++ | +++ | +++ | − | − | ++++ | Albuminuria | Fever High CRP |
| Still’s disease | +++ | + | + | − | − | ++++ | Skin rash Synovitis Pleural/pericardial effusions Cardiomyositis | |
| Sjӧgren syndrome | ++ | ++ | + | + | − | Variable | Tubulointerstitial nephritis Sicca | Sicca more severe in Sjӧgren syndrome Strongly positive autoantibodies |
| Autoimmune lymphoproliferative syndrome | ++++ | + | + | + | − | Rare | αβ double negative T cells FAS gene mutations Lymphocytosis Immune cytopenias | |
| Eosinophilic granulomatosis with polyangiitis | +++ | +++ | ++ | ++++ | − | ++++ | Asthma Atopy High IgE | Cardiomyopathy/myocarditis Skin involvement |
| Lymphocyte-variant hypereosinophilic syndrome | + | + | + | ++++ | − | ++ | Asthma Atopy High IgE | Skin lesions in >90% of patients with L-HES |
| IgG4-secreting B-cell lymphoma | ++ (or monoclonal) | ++ | ++++ | + | + | ++ | Clonal B cells | |
| T-cell NHL (AITCL, HSTCL) | ++ | ++ | ++ | + | + | ++ | Clonal T cells | |
| Rosai-Dorfman-Destombes disease | +++ | ++ | +++ | + | + | ++ | Autoimmune pancreatitis Hypertrophic pachymeningitis | Skin Bone Large histiocytes with emperipolesis MAPK mutations |
| Erdheim-Chester disease | ++ | + | ++ | − | ++ (hairy kidney) | +++ | Skin (xanthelasmas) Bone Large histiocytes BRAF in 50% | |
| Langerhan’s cell histiocytosis | + | + | + | + | + | +++ | Skin (xanthelasmas) Bone Liver CD1a+ histiocytes BRAF in 50% | |
| Sarcoidosis | ++ (PHGG or MGUS) | + | + | + | − | ++ | Pulmonary lesions | Uveitis Erythema nodosum High ACE level Noncaseating granuloma |
| Disease . | PHGG . | High serum IgG4 . | IgG4-enriched LAD . | Eosinophilia . | RPF . | High CRP . | Other overlap with IgG4-RD . | Contrasting features and notes . |
|---|---|---|---|---|---|---|---|---|
| IgG4-RD—proliferative | ++++ | ++++ | ++++ | ++ | + | Rare | N/A | Skin, synovium, bone, parenchymal brain involvement rare Autoantibodies negative or weak positive |
| IgG4-RD—fibrotic | ++ | ++ | ++ | + | ++++ | Typically low, but can be high in active aortitis | N/A | Skin, synovium, parenchymal brain involvement rare Nasal/facial bones can be involved in EAF but other bones are not involved Autoantibodies negative or weak positive |
| Multicentric CD (particularly iMCD-IPL) | +++ | +++ | +++ | − | − | ++++ | Albuminuria | Fever High CRP |
| Still’s disease | +++ | + | + | − | − | ++++ | Skin rash Synovitis Pleural/pericardial effusions Cardiomyositis | |
| Sjӧgren syndrome | ++ | ++ | + | + | − | Variable | Tubulointerstitial nephritis Sicca | Sicca more severe in Sjӧgren syndrome Strongly positive autoantibodies |
| Autoimmune lymphoproliferative syndrome | ++++ | + | + | + | − | Rare | αβ double negative T cells FAS gene mutations Lymphocytosis Immune cytopenias | |
| Eosinophilic granulomatosis with polyangiitis | +++ | +++ | ++ | ++++ | − | ++++ | Asthma Atopy High IgE | Cardiomyopathy/myocarditis Skin involvement |
| Lymphocyte-variant hypereosinophilic syndrome | + | + | + | ++++ | − | ++ | Asthma Atopy High IgE | Skin lesions in >90% of patients with L-HES |
| IgG4-secreting B-cell lymphoma | ++ (or monoclonal) | ++ | ++++ | + | + | ++ | Clonal B cells | |
| T-cell NHL (AITCL, HSTCL) | ++ | ++ | ++ | + | + | ++ | Clonal T cells | |
| Rosai-Dorfman-Destombes disease | +++ | ++ | +++ | + | + | ++ | Autoimmune pancreatitis Hypertrophic pachymeningitis | Skin Bone Large histiocytes with emperipolesis MAPK mutations |
| Erdheim-Chester disease | ++ | + | ++ | − | ++ (hairy kidney) | +++ | Skin (xanthelasmas) Bone Large histiocytes BRAF in 50% | |
| Langerhan’s cell histiocytosis | + | + | + | + | + | +++ | Skin (xanthelasmas) Bone Liver CD1a+ histiocytes BRAF in 50% | |
| Sarcoidosis | ++ (PHGG or MGUS) | + | + | + | − | ++ | Pulmonary lesions | Uveitis Erythema nodosum High ACE level Noncaseating granuloma |
ACE, angiotensin-converting enzyme; AITCL, angioimmunoblastic T cell lymphoma; EAF, eosinophilic angiocentric fibrosis; HSTCL, hepatosplenic T cell lymphoma; NHL, non-Hodgkin's lymphoma.