Immune deficiency/dysregulation -associated lymphoproliferative disorders. Revised classification and management

Significant advances in the field of lymphoma have resulted in two recent classification proposals, the International Consensus Classification (ICC) and the 5th edition WHO. A few entities are categorized differently in the ICC compared to the WHO. Nowhere is this more apparent than the immunodeficiency lymphoproliferative disorders. The three previous versions of the WHO classification (3rd, 4th and revised 4th editions) and the ICC focused on four clinical settings in which these lesions arise for primary categorization. In contrast the 2023 WHO 5th edition includes pathologic characteristics including morphology and viral status, in addition to clinical setting, as important information for lesion classification. In addition, the 2023 WHO recognizes a broader number of clinical scenarios in which these lesions arise, including not only traditional types of immune deficiency but also immune dysregulation. With this classification it is hoped that new treatment strategies will be developed leading to better patient outcomes.

Atypical lymphoplasmacytic and immunoblastic proliferation: A Systematic Review

Atypical lymphoplasmacytic and immunoblastic proliferation (ALPIBP) was first reported in 1984 as characteristic histological findings in lymph nodes associated with autoimmune diseases, but it has not been clearly defined to date. To summarize the histological characteristics and clinical diagnoses associated with ALPIBP, we searched MEDLINE and EMBASE for all peer-reviewed articles using keywords including "atypical lymphoplasmacytic and immunoblastic lymphadenopathy" from their inception to December 27, 2023. We also summarized the courses of three cases with a pathological diagnosis of ALPIBP. Nine articles with 52 cases were included. Among the total of 55 cases, including the three from our institution, the median age of the cases was 63.5 years with a female predominance (69.5%). Lymphadenopathy was generalized in 65.6% and regional in 34.4% of cases. RA (24.4%), SLE (24.4%), and autoimmune hemolytic anemia (20.0%), were common clinical diagnoses. A combination of cytotoxic chemotherapy was used in 15.6% of cases due to the suspicion of malignancy. Nodal T-follicular helper cell lymphoma, angioimmunoblastic type, methotrexate-associated lymphoproliferative disorders, and IgG4-related diseases were listed as important diseases that need to be pathologically differentiated from ALPIBP. This review summarizes the current understanding of the characteristics of ALPIBP. Given that underrecognition of ALPIBP could lead to overdiagnosis of hematological malignancy and unnecessary treatment, increased awareness of the condition in pathologists and clinicians is crucial.

Castleman disease and mimickers: Clinicopathological findings of atypical lymphoproliferative disorders associated with autoimmune disease

Atypical lymphoproliferative disorders (LPDs) related with autoimmune disease (AID) show marked clinicopathological diversity, which are defined as three distinct clinicopathological subtypes such as those resembling Castleman disease (CD), atypical paracortical hyperplasia with lymphoid follicles (APHLF), and atypical lymphoplasmacytic and immunoblastic proliferation (ALPIB). We studied excisional biopsy specimens from 31 patients with atypical LPDs associated with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren syndrome (SjS). The lesions in these 31 cases were classified into 6 (19.4%) cases resembling CD, 14 (45.2%) cases of APHLF, and 11 (35.5%) cases of ALPIB. Five cases (83.3%) resembling CD were in the active stage with systemic symptoms and multicentric lymphadenopathy. Thirteen cases (92.9%) of APHLF showed systemic symptoms, multicentric lymphadenopathy and abnormal laboratory findings. Histologic findings for cases resembling CD were rare in patients with RA and SjS. In AID patients, histologic findings for cases resembling CD or APHLF findings correlated with disease activity and multicentric lymphadenopathy. Six cases (54.5%) of ALPIB were in the active phase with systemic symptoms and multicentric lymphadenopathy. ALPIB tended to be unrelated to AID activity, especially in the majority of patients with no abnormal laboratory findings. Atypical LPDs associated with AID is a group of diseases that may be overdiagnosed and overtreated. The diagnosis of atypical LPDs associated with AID requires an understanding of the histological findings as well as a comprehensive assessment of the presence of systemic symptoms, the distribution of lymphadenopathy, and abnormal laboratory findings.

Clinicopathological differential diagnosis of IgG4-related disease: A historical overview and a proposal of the criteria for excluding mimickers of IgG4-related disease

IgG4-related disease (RD) is a relatively new entity, which was first proposed in 2001. Since then, clinical and pathological characteristics of the disease have been investigated. As IgG4-RD has been studied extensively, the diagnostic criteria for IgG4-RD of each organ and the comprehensive diagnostic criteria for IgG4-RD have also been developed. However, one of the biggest challenges in the field is distinguishing between IgG4-RD and mimickers, which show overlapping features with IgG4-RD. It is now known that some non-IgG4-RDs may meet the diagnostic criteria of IgG4-RD and can be misdiagnosed as IgG4-RD. However, accurate diagnosis is crucial, as the treatments for IgG4-RD and those for other diseases that may be misdiagnosed as IgG4-RD are different. This prompted us to create and propose comprehensive exclusion criteria for IgG4-RD. In this review, we have described the comprehensive exclusion criteria for IgG4-RD, with a historical overview of the disease. These exclusion criteria were recently created by the Research Program for Intractable Disease of the Ministry of Health, Labor, and Welfare of Japan, All Japan IgG4 team, to support correct and accurate diagnosis of IgG4-RD.

Sjögren's syndrome manifesting as clinicopathological features of TAFRO syndrome: A case report

RATIONALE

TAFRO syndrome is a newly proposed disorder that manifests as thrombocytopenia, anasarca, fever, reticulin myelofibrosis, renal dysfunction, and organomegaly. In this report, we describe the development of severe TAFRO syndrome-like systemic symptoms during the clinical course of juvenile-onset Sjögren's syndrome in a 32-year-old woman.

PATIENT CONCERNS

The patient was admitted due to dyspnea, fever, polyarthralgia, and generalized edema. She had been diagnosed with Sjögren's syndrome at the age of 14 years, based on histopathological examination of a biopsy of the minor salivary glands and the development of Raynaud's phenomenon, with no follow-up treatment required. On admission, she presented with anemia, elevated C-reactive protein levels, anasarca, and hepato-splenomegaly. A bone marrow examination revealed increased megakaryocytes with reticulin fibrosis, and the histopathology of an axillary lymph node was consistent with mixed-type Castleman disease. Eventually, she developed thrombocytopenia.

INTERVENTIONS

Her symptoms fulfilled all of the major and minor categories of the diagnostic criteria for TAFRO syndrome. However, considering her prior diagnosis, we assumed that the clinical presentation was consistent with an acute exacerbation of Sjögren's syndrome. Unlike typical cases of TAFRO syndrome, the administration of relatively low-dose prednisolone relieved her symptoms.

LESSONS

Differentiation between TAFRO syndrome and exacerbation of an autoimmune disease is clinically important, although this can be challenging. Identification of specific biomarkers for TAFRO syndrome would be clinically beneficial.

A case of IgG4-related kidney disease complicated by eosinophilic lung disease

IgG4-related disease is a systemic chronic inflammatory disorder characterized by a high blood level of IgG4 and the organ injuries by marked infiltration of IgG4-positive plasma cells and fibrosis. A 71-year-old male was hospitalized for a cough, malaise and anorexia. IgG4-related disease was suspected due to marked elevation of the serum IgG4 level. However, on lung biopsy, only eosinophil infiltration was demonstrated with no plasma cell infiltration. Otherwise abdominal contrast-enhanced CT showed mild enlargement of the bilateral kidneys and many differed contrasted areas and FDG PET-CT. Moreover, renal biopsy specimens showed typical tubulointerstitial nephritis with a large number of IgG4-positive plasma cells infiltration (the IgG4/IgG-positive cell rate, 89 %) and fibrosis. We diagnosed this patient as typical IgG4-related kidney disease. He was treated by the moderate dose of prednisolone (0.8 mg/kg/day) alone, and showed prompt response in the clinical condition, and both the lung and kidney lesions. In this case, it was useful for diagnosis of IgG4-related diseases to evaluate an image such as abdominal contrast-enhanced CT and FDG PET-CT. Our case might be one of the possible patterns of IgG4-related lung diseases. In addition, we thought that there might be an association between hypereosinophilia and IgG4-related kidney disease.

IgG4-Related Lymphadenopathy

Lymphadenopathy is frequently observed in patients with immunoglobulin G4-related disease (IgG4-RD) and sometimes appears as the first manifestation of the disease. The diagnosis of IgG4-related lymphadenopathy is complicated owing to a great histological diversity, with at least 5 histological subtypes. Indeed, lymph node biopsy may be performed under the suspicion that the lymphadenopathy is a malignant lymphoma or other lymphoproliferative disorder. The diagnosis of IgG4-RD is characterized by both elevated serum IgG4 (>135 mg/dL) and histopathological features, including a dense lymphoplasmacytic infiltrate rich in IgG4(+) plasma cells (IgG4(+)/IgG(+) plasma cell ratio >40%). However, patients with hyper-interleukin (IL-) 6 syndromes such as multicentric Castleman's disease, rheumatoid arthritis, and other immune-mediated conditions frequently show lymph node involvement and often fulfill the diagnostic criteria for IgG4-RD. Owing to these factors, IgG4-RD cannot be differentiated from hyper-IL-6 syndromes on the basis of histological findings alone. Laboratory analyses are crucial to differentiate between the 2 diseases. Hyper-IL-6 syndromes are characterized by elevated serum levels of IgG, IgA, IgM, and C-reactive protein (CRP); thrombocytosis; anemia; hypoalbuminemia; hypocholesterolemia. In contrast, IgG4-RD does not share any of these characteristics. Therefore, the diagnosis of IgG4-RD requires not only pathological findings but also clinical and laboratory analyses.