Not All Küttner Tumors Are IgG4-Related Disease (IgG4-RD).

Küttner tumor is an uncommon cause of salivary gland enlargement that most frequently affects the submandibular gland. More recently it has been considered a manifestation of IgG4-related disease (IgG4-RD) and synonymous with chronic sclerosing sialadenitis (CSS). We present a series of cases to emphasize this clinical entity as a disease pattern and presentation that is separate from IgG4-RD. Retrospective case series of 3 patients with unilateral salivary gland enlargement, or "Küttner tumor," histologically classified as "chronic sclerosing sialadenitis," The clinical history, radiology reports, laboratory studies, and pathology slides were reviewed for each case. Radiology showed discrete unilateral mass-like lesions in all three cases. Immunohistochemistry showed reduced tissue IgG4-positive plasma cells in two cases and increased numbers in one case, but insufficient to diagnose IgG4-RD. Storiform fibrosis was not seen in all cases and did not coincide with increased IgG4-positive plasma cells. A systemic workup, including serum IgG4 levels in two cases, was normal. A brief review of the literature on the spectrum of salivary gland involvement by IgG4-RD is presented. Küttner tumor is not necessarily the same as chronic sclerosing sialadenitis and is not always associated with IgG4-related disease. This report includes the second documented case of Küttner tumor of the sublingual gland.