IgG4-related disease is a recently recognized systemic syndrome characterized by mass-forming lesions with lymphoplasmacytic infiltration, increase in the number of IgG4 þ cells in affected tissues and elevation of serum IgG4 levels. In 2009, we were the first to report skin lesions in patients with IgG4-related disease, but no large case series has been reported and clinicopathological findings remain unclear. To clarify these features, we herein report 10 patients (9 men and 1 woman; median age, 64 years; age range, 46-81 years) with IgG4-related skin disease. All patients had erythematous and itchy plaques or subcutaneous nodules on the skin of the head and neck, particularly in the periauricular, cheek, and mandible regions, except for one patient, whose forearm and waist skin were affected. In addition, eight patients had extracutaneous lesions: these were found on the lymph nodes in six patients, the lacrimal glands in three patients, the parotid glands in three patients, and the kidney in one patient. Histologically examined extracutaneous lesions were consistent with IgG4-related disease; five of six lymph node lesions showed progressively transformed germinal centers-type IgG4-related lymphadenopathy. Cases of IgG4-related skin disease were classified into two histological patterns: those exhibiting a nodular dermatitis pattern and those with a subcutaneous nodule pattern. The infiltrate was rich in plasma cells, small lymphocytes, and eosinophils; the majority of the plasma cells were IgG4 þ . The IgG4 þ cell count was 49-396 per high-power field (mean±s.d., 172±129), with an IgG4 þ /IgG þ cell ratio ranging from 62 to 92%. Serum IgG4 levels were elevated in all examined patients. In conclusion, patients with IgG4-related skin disease had uniform clinicopathology. Lesions were frequently present on the skin of the periauricular, cheek, and mandible regions, and were frequently accompanied by IgG4-related lymphadenopathy.

IgG4-related disease is a systemic disorder with unique clinicopathological features and uncertain etiological features and is frequently related to allergic disease. T helper 2 and regulatory T-cell cytokines have been reported to be upregulated in the affected tissues; thus, the production of these cytokines by T helper 2 and regulatory T cells has been suggested as an important factor in the pathogenesis of IgG4-related disease. However, it is not yet clear which cells produce these cytokines in IgG4-related disease, and some aspects of the disorder cannot be completely explained by T-cell-related processes. To address this, we analyzed paraffinembedded sections of tissues from nine cases of IgG4-related submandibular gland disease, five cases of submandibular sialolithiasis, and six cases of normal submandibular gland in order to identify potential key players in the pathogenesis of IgG4-related disease. Real-time polymerase chain reaction analysis confirmed the significant upregulation of interleukin (IL)4, IL10, and transforming growth factor beta 1 (TGFb1) in IgG4-related disease. Interestingly, immunohistochemical studies indicated the presence of mast cells expressing these cytokines in diseased tissues. In addition, dual immunofluorescence assays identified cells that were double-positive for each cytokine and for KIT, which is expressed by mast cells. In contrast, the distribution of T cells did not correlate with cytokine distribution in affected tissues. We also found that the mast cells were strongly positive for IgE. This observation supports the hypothesis that mast cells are involved in IgG4-related disease, as mast cells are known to be closely related to allergic reactions and are activated in the presence of elevated non-specific IgE levels. In conclusion, our results indicate that mast cells produce T helper 2 and regulatory T-cell cytokines in tissues affected by IgG4-related disease and possibly have an important role in disease pathogenesis.

Recently, atypical Castleman's disease (CD) was reported in Japan. This disease is considered as TAFRO syndrome or non-idiopathic plasmacytic lymphadenopathy (IPL), a constellation of clinical symptoms, namely, thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly without hyper-γ-globulinemia. Histopathologically, this disease is similar to hyaline vascular (HV)-type CD. Here, we present a 43-year-old Japanese woman meeting the clinical criteria of TAFRO syndrome who was successfully treated with combined corticosteroid therapy. She showed a rapidly progressive course of thrombocytopenia, systemic lymphadenopathy, fever, anasarca, and increase in acute inflammatory proteins without hyper-γ-globulinemia. Lymph node biopsy was performed and revealed HV-type CD without human herpes virus 8 infection, which was clinicopathologically compatible with non-IPL. The association of these atypical features with well-known multicentric Castleman's disease (MCD), namely, HV-type histology with systemic lymphadenopathy, marked thrombocytopenia even with a high level of interleukin-6, and increased acute inflammatory proteins without hyper-γ-globulinemia, suggests that TAFRO syndrome as presented in our case is a novel entity, which may have been diagnosed as MCD in the past. To define this novel entity more clearly and to demonstrate its etiology, further nationwide surveys of this syndrome and MCD are needed.

IgG4-related disease is a recently proposed clinical entity with several unique clinicopathological features. A chronic inflammatory state with marked fibrosis, which can often be mistaken for malignancy, especially by clinical imaging analyses, unifies these features. In the present report, we describe a case of IgG4-producing mucosa-associated lymphoid tissue lymphoma mimicking IgG4-related disease. The patient was a 55-year-old male who was being followed for right orbital tumor over 1.5 years. The lesion had recently increased in size, so a biopsy was performed. Histologically, the lesion was consistent with IgG4-related disease ; however, IgG4⁺ plasma cells showed immunoglobulin light-chain restriction and immunoglobulin heavy chain gene rearrangement was detected in the lesion. Therefore, the lesion was diagnosed as IgG4-producing mucosa-associated lymphoid tissue lymphoma. In conclusion, in histological diagnosis of IgG4-related disease, it is important to examine not only IgG4-immunostain but also immunoglobulin light-chain restriction.

In the 34 cases, univariate analysis for disease-free survival indicated high-level infiltration of Tregs (CD4(+)Foxp3+) into both cancer nests and stroma and presence of helper T (CD4(+)Foxp3-) cells in cancer stroma as potential predictors of significantly worse prognosis. In early-stage cases (stage I/II), high-level infiltration of Tregs in cancer nests correlated significantly with poor disease-free survival rate. Multivariate analysis for disease-free survival found no independent variables.

We previously suggested a relationship between ocular immunoglobulin (Ig)G4-related disease (IgG4-RD) and marginal zone lymphomas (MZLs). However, the cytokine background associated with these disorders and whether it differs between ocular adnexal MZLs with (IgG4-associated MZL) and without (IgG4-negative MZL) numerous IgG4+ plasma cells are unknown. In this study, we identified the mRNA expression pattern of Th2 and regulatory T-cell (Treg) cytokines in IgG4-RD and in IgG4-associated MZL and IgG4-negative MZL using real-time polymerase chain reaction analysis. Ocular IgG4-RD and IgG4-associated MZL exhibited significantly higher expression ratios of interleukin (IL)-4/β-actin, IL-10/β-actin, IL-13/β-actin, transforming growth factor (TGF) β1/β-actin, and FOXP3/β-actin than did IgG4-negative MZL (p < 0.05). This finding further supports our prior observations that a significant subset of ocular MZLs arises in the setting of IgG4-RD. Furthermore, the presence of a different inflammatory background in IgG4-negative MZLs suggests that IgG4-associated MZLs may have a different pathogenesis.

Laennec's capsule is a proper membrane of the liver, first described by Réné T. H. Laennec in 1802, covering not only the entire surface of the liver but also the intrahepatic parenchyma surrounding the Glissonean pedicles and the hepatic veins (HVs). It is an essential structure for establishing liver resection, especially anatomic liver resection, which involves the isolation of the extrahepatic Glissonean pedicles and the exposure of the main HVs. Regarding the location of the capsule, Laennec and Couinaud described it as adjacent to the confluence of the main HVs. Whereas, Hayashi revealed it to be around the peripheral branches. Recently, Kiguchi first reported that Laennec's capsule consists of two layers and proposed novel surgical procedures using this concept. Yet, its existence is still debated. Herein, we show the precise anatomy and histology of Laennec's capsule around the HVs including its twolayered composition: one derived from the pericardium (the cardiac Laennec's capsule) and the other from the proper membrane (the hepatic Laennec's capsule). Using these findings, we demonstrate three surgical approaches to the main HVs and emphasize the significance of the craniocaudal parenchymal dissection especially for laparoscopic anatomic liver resection.

No abstract