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

Calcifying fibrous tumor of the gastrointestinal tract: A clinicopathologic review and update

Calcifying fibrous tumor (CFT) is a rare mesenchymal lesion that has been documented throughout the gastrointestinal tract. Gastrointestinal CFTs may occur at virtually any age, with a predilection for adults and for females. They occur most commonly in the stomach and the small and large intestines. CFTs are most often found incidentally, cured by local resection, and have a low risk of recurrence. Histology shows three characteristic features: Spindle cell proliferations within a densely hyalinized stroma, scattered calcifications, and lymphoplasmacytic inflammation. CFTs are immunoreactive for CD34, vimentin and factor XIIIa, helping to distinguish them from other benign mesenchymal neoplasms. The differential diagnosis of CFTs includes sclerosing gastrointestinal stromal tumor, leiomyoma, schwannoma, solitary fibrous tumor, inflammatory myofibroblastic tumor, plexiform fibromyxoma, fibromatosis, sclerosing mesenteritis, and reactive nodular fibrous pseudotumor. The pathogenesis of CFTs remains unclear, but some have hypothesized that they may be linked to IgG4-related disease, inflammatory myofibroblastic lesions, hyaline vascular type Castleman disease, sclerosing angiomatoid nodular transformation of the spleen, or trauma.

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

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.