Diffuse large B-cell lymphoma - an unusual cause of a rapidly enlarging thyroid mass: A large case series

Presentation of a rapidly enlarging thyroid mass (RETM) typically elicits concern for anaplastic thyroid carcinoma (ATC). However, primary thyroid lymphoma (PTL), specifically diffuse large B-cell lymphoma (DLBCL), has a similar clinical presentation and should be considered in the initial differential diagnosis as they can quickly alter clinical work-up and management. This is a single institution case series of two years, 2022–2024, of six patients (Five males and one female, aged 63–90 years old) with RETM with biopsy proven DLBCL. Four patients had history of hypothyroidism. Three patients presented to the emergency department for worsening dyspnea and dysphagia while three were seen outpatient with milder symptoms such as dysphonia or dysphagia. Definitive diagnosis of DLBCL was determined by fine needle aspiration, core, or excisional biopsy. Consideration of ATC was evaluated with onsite cytology review and BRAF testing by pyrosequencing. The subtypes of DLBCL varied; three were identified as germinal center subtype, one was activated B-cell subtype, and the remaining two cases were unspecified. Various treatments were initiated including R-CHOP, mini-R-CHOP, Pola-R-CHOP, and R-CEOP in addition to airway stabilization measures. Primary thyroid lymphomas, specifically DLBCL, are an uncommon cause of RETM. Like ATC, they can present with progressive symptoms of dyspnea, dysphagia, and dysphonia secondary to local tissue invasion and mass effect. This case series demonstrates the importance of sending initial pathology for lymphoma work up, especially given a history of hypothyroidism, in addition to typical cytopathology and BRAF testing for ATC for RETM.