The growing utilization of needle biopsy has challenged the current pathology consensus of IgG4-related disease (IgG4-RD). The aims of this study were to identify the histological characteristics of needle biopsy and surgical specimens and evaluate the ability of needle biopsy in histological diagnosis of IgG4-RD.
Biopsies from patients who were referred to as IgG4-RD by the 2019 ACR/EULAR IgG4-RD classification criteria in Peking University People's Hospital from 2012 to 2019 were re-evaluated. Typical histological features and diagnostic categories were compared between needle biopsy and surgical biopsy.
In total, 69 patients met the 2019 ACR/EULAR classification criteria and 72 biopsies of them were re-evaluated. All cases showed lymphoplasmacytic infiltrate, while storiform fibrosis and obliterative phlebitis were only present in 35 (48.6%) and 23 (31.9%) specimens, respectively. Storiform fibrosis was more likely to be seen in retroperitoneum lesion (P = 0.033). Surgical biopsy showed significantly higher IgG4+ plasma cells/high-power field (IgG4/HPF) count (P < 0.01) and higher proportion of IgG4/HPF > 10 (P < 0.01). No significant difference was observed with regard to the ratio of IgG4+ plasma cells/IgG+ plasma cells (IgG4/IgG) (P = 0.399), storiform fibrosis (P = 0.739), and obliterative phletibis (P = 0.153). According to the 2011 comprehensive diagnostic criteria, patients who performed a needle biopsy were less likely to be probable IgG4-RD (P = 0.045). Based on the 2011 pathology consensus, needle biopsy was less likely to be diagnosed as IgG4-RD (P < 0.01), especially to be highly suggestive IgG4-RD (P < 0.01). Only 1/18 (5.6%) needle salivary specimens fulfilled the cutoff of IgG4/HPF > 100, which was significantly less than 15/23 (65.2%) of surgical ones (P < 0.01).
Needle biopsy shows an inferiority in detecting IgG4/HPF count but not in IgG4/IgG ratio, storiform fibrosis, and obliterative phlebitis. Compared with surgical samples, needle biopsy is less likely to obtain a histological diagnosis of IgG4-RD. A different IgG4/HPF threshold for needle biopsy of the salivary glands may be considered.