IgG4-type Multiple Myeloma with Diffuse Enlargement of the Thyroid Requiring Differentiation from IgG4-related Disease

IgG4 plasma cell neoplasm in liver transplant biopsy masquerading as rejection

IgG4 plasma cell neoplasm and myeloma are rare disease entities, not associated with systemic fibroinflammatory IgG4 related disease. We herein present a case of IgG4 plasma cell neoplasm in a liver transplant biopsy. A 55 year old female was treated with living donor transplant and had a complicated post-operative course. Three months post-transplant, she presented with small for size syndrome, biliary stricture, and inferior vena cava stenosis. Concomitant liver biopsy revealed mild acute cellular rejection with central perivenulitis pattern, and mild centrilobular fibrosis. She was treated with steroids which resulted in improvement of liver enzymes. Seven months post-transplant, she presented with subtherapeutic prograf levels and cholestatic pattern of elevated liver tests. ERCP revealed a stone which was removed. Hematological evaluation revealed an abnormal serum protein electrophoresis (SPEP). Monoclonal IgG kappa was elevated along with mildly elevated free Kappa/Lambda ratio. She was followed up and readmitted two months later for worsening liver function tests. The liver biopsy showed monotypic Kappa-and IgG4-restricted plasma cell infiltrates in portal, periportal, sinusoidal and centrilobular regions, compatible with plasma cell neoplasm. In the clinical context of positivity for a serum M-spike, the monoclonal hepatic infiltrates were deemed consistent with a Kappa-and IgG4-restricted plasma cell neoplasm. Patient was treated with pulsed steroids, and liver function tests subsequently downtrended. She was followed up by Hemoncology, and the treatment plan included carfilzomib-based induction therapy and dexamethasone to prevent end-organ damage from evolving myeloma. In the meanwhile, she developed acute appendicitis, underwent appendectomy, and passed away in the post-operative period.

Reshaping the Concept of Riedel's Thyroiditis into the Larger Frame of IgG4-Related Disease (Spectrum of IgG4-Related Thyroid Disease)

Recently, Riedel's thyroiditis (RT) was assimilated into the larger spectrum of immunoglobulin IgG4-related disease (IgG4-RD) in addition to a particular frame of IgG4-related thyroid disease (IgG4-RTD), underlying IgG4-RT, IgG4-associated Hashimoto's thyroiditis (and its fibrotic variant), and IgG4-related Graves's disease. Our objective was to overview recent data on RT, particularly IgG4-RD and IgG4-RTD. The case and study- sample analysis (2019-2023) included 293 articles and selected 18 original studies: nine single case reports (N = 9, female/male = 2/1, aged: 34-79 years, 5/9 patients with serum IgG4 available data, 2/5 with high serum IgG4) and four case series (N = 21; 4/5 series provided data on IgG4 profile, 3/21 had serum IgG4 assays, and 2/3 had abnormally high values). IgG4-RD and thyroid findings were analyzed in three cohorts (N = 25). Another two studies (N = 11) specifically addressed IgG4-RTD components. On presentation, the patients may have hypothyroidism, transitory thyrotoxicosis, goiter, long-term history of positive anti-thyroid antibodies, and hypoechoic ultrasound thyroid pattern. The 5-year analysis (N = 66) showed the rate of serum IgG4 evaluation remained low; normal values do not exclude RT. Mandatory histological and immunohistochemistry reports point out a high content of IgG4-carrying plasma cells and IgG4/IgG ratio. Unless clinically evident, histological confirmation provides a prompt indication of starting corticoid therapy since this is the first-line option. Surgery, if feasible, is selective (non-responders to medical therapy, emergency tracheal intervention, and open/core needle biopsy). Current open issues are identifying the role of serum IgG4 assays in patients with IgG4-RD, finding out if all cases of RT are IgG4-mediated, applying IgG4-RTD criteria of differentiation among four entities, and providing an RT/IgG4-RTD guideline from diagnosis to therapy. It remains that the central aim of approaching RT in daily practice is the early index of suspicion in order to select patients referred for further procedures that provide enough histological/immunohistochemistry material to confirm RT and its high IgG4 burden.

Clinical differences between IgG4 Hashimoto's thyroiditis and primary thyroid lymphoma

Background

Hashimoto's thyroiditis (HT) can be divided into IgG4 HT and non-IgG4 HT based on IgG4 and IgG immunohistochemical staining. In clinical practice, it is often necessary to identify diseases such as primary thyroid lymphoma (PTL) and IgG4 HT when a patient presents with a rapidly enlarged thyroid. The aim of our study was to uncover the differential points between the two diseases.

Methods

Clinical information from 19 IgG4 HT and 10 PTL patients was obtained from the patients' medical records, including age, sex, main clinical manifestation, thyroid functional status, the presence of serum anti-thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and thyroid ultrasonography results. Thyroid sections from all patients were collected to detect IgG4 and IgG expression by immunohistochemical staining.

Results

The IgG4 HT patients were significantly younger than those in the PTL group (39.68 ± 10.95 vs 66.20 ± 10.23 years, P < 0.001). There were no significant differences in the sex distribution or TgAb- or TPOAb-positive rates. The PTL group had a higher prevalence of clinical hypothyroidism than the IgG4 HT group (P = 0.016). In the PTL group, thyroid lesions were more likely to exhibit hypoechogenicity (6/6 vs 1/19, P < 0.001) on ultrasound images. In the PTL group, two patients met the immunohistochemical cut-off value of the criteria for IgG4 HT.

Conclusions

Simply relying on immunohistochemistry for IgG4 cannot diagnose IgG4 HT correctly when a patient presents with rapid thyroid enlargement. A combination of clinical and pathological analyses will help distinguish IgG4 HT from PTL which may be with abundant IgG4-positive plasma cells.

Polyclonal hypergammaglobulinaemia: assessment, clinical interpretation, and management

This Review outlines a practical approach to assessing and managing polyclonal hypergammaglobulinaemia in adults. Polyclonal hypergammaglobulinaemia is most commonly caused by liver disease, immune dysregulation, or inflammation, but can also provide an important diagnostic clue of rare diseases such as histiocyte disorders, autoimmune lymphoproliferative syndrome, Castleman disease, and IgG4-related disease. Causes of polyclonal hypergammaglobulinaemia can be divided into eight categories: liver disease, autoimmune disease and vasculitis, infection and inflammation, non-haematological malignancy, haematological disorders, IgG4-related disease, immunodeficiency syndromes, and iatrogenic (from immunoglobulin therapy). Measuring serum concentrations of C-reactive protein and IgG subclasses are helpful in diagnosis. IL-6-mediated inflammation, associated with persistently elevated C-reactive protein concentrations (≥30 mg/L), is an important driver of polyclonal hypergammaglobulinaemia in some cases. Although the presence of markedly elevated serum IgG4 concentrations (>5 g/L) is around 90% specific for diagnosing IgG4-related disease, mildly elevated serum IgG4 concentrations are seen in many conditions. In most cases, managing polyclonal hypergammaglobulinaemia simply involves treating the underlying condition. Rarely, however, polyclonal hypergammaglobulinaemia can lead to hyperviscosity, requiring plasmapheresis.