Thymic hyperplasia with lymphoepithelial sialadenitis-like features A single-institution series of 21 new cases.

Thymic hyperplasia with lymphoepithelial sialadenitis-like features (TH-LESA) is a rare tumor-like condition of the thymus gland with less than 50 cases reported in the literature. Named after its resemblance to lymphoepithelial sialadenitis (LESA) of the salivary glands, TH-LESA is a distinct form of thymic hyperplasia characterized by simultaneous epithelial and lymphoid hyperplasia. Recently, TH-LESA has been linked with autoimmune diseases (AID) and a potential for developing thymic lymphoma. We report 21 additional cases of surgically resected TH-LESA in 15 women and 6 men (mean age 53 years, range 29-74); most cases were identified incidentally. Eleven (52%) patients were African American, 7 (33%) were white and 1 (5%) was Asian; race was unknown for 2 patients. Five (24%) patients had a history of non-myasthenic AID, including systemic lupus erythematosus, Sjögren syndrome, and rheumatoid arthritis. Two (9.5%) patients developed lymphoma within the hyperplastic process: 1 extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) and 1 nodular sclerosis Hodgkin lymphoma (NSHL). Clinical follow-up revealed that 11 patients were alive 3 to 240 months postoperatively and 1 patient had died of cardiac disease; follow-up was unavailable for 9 patients. In this largest single-institution series to date, we confirm the reported association of TH-LESA with AID and lymphoma. Recognition of NSHL developing in TH-LESA expands the spectrum of lymphomas reported in association with this condition. Furthermore, TH-LESA appears to preferentially affect African American women, unlike patients with salivary gland LESA, perhaps providing an epidemiologic clue to its pathogenesis.