Invasive fibrous (Riedel's) thyroiditis is usually insidious in onset with a protracted clinical course. Its etiology is obscure but its occasional acute onset and rapid progression suggest more than one possible cause. It is sometimes associated with similar fibrosclerotic processes in other areas (mediastinum, lungs, orbits, retroperitoneal tissues, common bile duct) in the syndrome of so-called multifocal fibrosclerosis. A patient presented with previously unreported association of Riedel's thyroiditis and bilateral fibrous parotitis.
Hines RC, Scheuermann HA, Royster HP, Rose E. Invasive Fibrous (Riedel's) Thyroiditis With Bilateral Fibrous Parotitis. JAMA. 1970;213(5):869–871. doi:10.1001/jama.1970.03170310147054