Classic IgG4-related sclerosing mastitis is not so classic.

IgG4-related sclerosing mastitis (IgG4-RM) is a rare, benign, mass-forming fibroinflammatory disease of the breast that can mimic a neoplastic process and pose a diagnostic challenge to clinicians and pathologists. We present a case of IgG4-RM in an 84-year-old woman and highlight the characteristic morphologic findings that should allow the pathologist to raise the possibility of this entity. We also briefly discuss pathophysiology and differential diagnosis.

The incidence of giant cell arteritis in Ontario, Canada.

Objective: The incidence of giant cell arteritis (GCA) is insufficiently documented for Canada, but important to ascertain for public health planning. We estimate the incidence of biopsy-proven GCA (BPGCA) in Kingston, Ontario, and for the province of Ontario.

Method: The number of cases of BPGCA was tabulated from retrospective chart review of all temporal artery biopsies (TABx) in Kingston, Ontario from 2011-15.