A Case of Inflammatory Lung Disease and Retroperitoneal Fibrosis Attributed to Systemic IgG4-related Disease

Recently, immunoglobulin (Ig) G4-related diseases such as autoimmune pancreatitis (AIP), sclerosingsialadenitis, retroperitoneal fibrosis, and sclerosing cholangitis have been reported. IgG4-related diseases arecharacterized by high serum IgG4 concentrations, sclerosing inflammation with numerous IgG4-positiveplasma cells, and steroid sensitivity, irrespective of their organ of origin. We describe a case of inflammatorylung disease and retroperitoneal fibrosis, suggested to involve IgG4. The patient was a 76-year-old man. Acomputed tomographic scan of the chest showed nodular air-space consolidation in the left upper lobe. Theserum IgG4 concentration was abnormally elevated, but there was no evidence of AIP. Bilateral hydronephrosisassociated with thickened soft tissue around the abdominal aorta had been diagnosed previously. Hehad undergone surgery, and retroperitoneal fibrosis was diagnosed histologically (hematoxylin and eosinstain). Histological examination of bronchoscopic specimens taken from the left S3 region showed mononuclear-cell infiltration of the fibrotic bronchial wall, including many IgG4-positive plasma cells. Specimens ofthe region affected by retroperitoneal fibrosis were retrospectively reanalyzed, and the cells were positivefor IgG4 on immunostaining, similar to the lung tissue. The patient responded to treatment with corticosteroids.In conclusion, the present case shared many clinical and clinicopathological similarities with systemicIgG4-related autoimmune disease. To our knowledge, however, this is the first reported case of inflammatorylung disease with retroperitoneal fibrosis in a patient with systemic IgG4-related autoimmune disease

Genetic alterations that deregulate RB and PDGFRA signaling pathways drive tumor progression in IDH2-mutant astrocytoma

Abstract In IDH-mutant astrocytoma, IDH2 mutation is quite rare and biological mechanisms underlying tumor progression in IDH2-mutant astrocytoma remain elusive. Here, we report a unique case of IDH2 mutant astrocytoma, CNS WHO grade 3 that developed tumor progression. We performed a comprehensive genomic and epigenomic analysis for primary and recurrent tumors and found that both tumors harbored recurrent IDH2 R172K and TP53 R248W mutation with CDKN2A/B hemizygous deletion. We also found amplifications of CDK4 and MDM2 with PDGFRA gain in the recurrent tumor and upregulated protein expressions of these genes. We further developed, for the first time, a xenograft mouse model of IDH2 R172K and TP53 R248W mutant astrocytoma from the recurrent tumor, but not from the primary tumor. Consistent with parent recurrent tumor cells, amplifications of CDK4 and MDM2 and PDGFRA gain were found, while CDKN2A/B was identified as homozygous deletion in the xenografts, qualifying for integrated diagnosis of astrocytoma, IDH2-mutant, CNS WHO grade 4. Cell viability assay found that CDK4/6 inhibitor and PDGFR inhibitor potently decreased cell viability in recurrent tumor cells, as compared to primary tumor cells. These findings suggest that gene alterations that activate retinoblastoma (RB) signaling pathways and PDGFR may drive tumor progression and xenograft formation in IDH2-mutant astrocytoma, which is equivalent to progressive IDH1-mutant astrocytoma. Also, our findings suggest that these genomic alterations may represent therapeutic targets in IDH2-mutant astrocytoma