Calcifying fibrous tumour: An IgG4‐related disease or not?

• Published in: International journal of experimental pathology 2020-02, Vol.101 (1-2), p.38-44
• Main Authors: Hu, Yu‐Hsuan, Yu, Chen‐Tang, Chen, Chih‐Jung, Wen, Mei‐Chin
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Antibodies; Autoimmune diseases; Calcification; calcifying fibrous tumour; Calcinosis - classification; Calcinosis - immunology; Calcinosis - pathology; Child; Child, Preschool; Female; Fibrosis; Humans; IgG4‐positive plasma cells; IgG4‐related disease; Immunoglobulin G; Immunoglobulin G - analysis; Immunoglobulin G4-Related Disease - classification; Immunoglobulin G4-Related Disease - immunology; Immunoglobulin G4-Related Disease - pathology; Male; Middle Aged; Neoplasms, Fibrous Tissue - classification; Neoplasms, Fibrous Tissue - immunology; Neoplasms, Fibrous Tissue - pathology; Original; Plasma; Plasma cells; Plasma Cells - immunology; Plasma Cells - pathology; Retrospective Studies; Stromal Cells - pathology; Tumors; Young Adult
• ISSN: 0959-9673; 1365-2613
• DOI: 10.1111/iep.12339

Summary Calcifying fibrous tumour (CFT) has some of the histopathological features, such as abundant plasma cells and stromal fibrosis, that are exhibited by IgG4‐related diseases (IgG4‐RD). The possible role of IgG4‐positive plasma cells in calcifying fibrous tumour was investigated. The aim of this study was to determine any potential relationship between IgG4‐RD and CFT. Thirteen cases with a total of 16 CFTs were reviewed. Lesion samples were immunostained with anti‐IgG4 and anti‐IgG antibodies. The number of IgG4‐positive and IgG‐positive plasma cells (IgG + PC) and their ratios were estimated. Plasma cells were found in all tumours. IgG4‐positive plasma cells ranged from 0 to 71 per high‐power field (HPF; mean 17.8/HPF), and IgG + PC ranged from 2 to 93/HPF (mean 42.6/HPF). The IgG4/IgG ratio ranged from 0% to 80% (mean 29%). There were seven tumours with the ratio of IgG4/IgG + PC that exceeded 40%. Various degrees of stromal fibrosis were present in eight tumours. All tumours have variable calcification. The histopathological features of CFT were found to be similar to those of IgG4‐RD. Some CFT also showed a high number of IgG4‐positive plasma cells, and the ratio of IgG4/IgG + PC exceeded 40%, most notably in patients with concomitant inflammatory or autoimmune disease. The long‐term follow‐up showed no evidence of IgG4‐RD in any of these patients. Our findings suggest that while CFT overlaps morphologically with IgG4‐RD, it probably should not be classified as an IgG4‐RD.