Abstract

Introduction: Extranodal non-Hodgkin lymphoma of the thyroid, also referred to as primary thyroid lymphoma (PTL), is a rare subtype of non-Hodgkin lymphoma. Clinically, PTL typically manifests as a rapidly enlarging neck mass that may precipitate compressive symptoms. Because of its rarity and non-specific clinical presentation, PTL is often misdiagnosed pre-operatively. In addition to core-needle biopsy, a function-preserving lobectomy with intra-operative frozen-section examination may be appropriate in selected cases. Case description: We describe a 52-year-old Vietnamese woman who presented with a rapidly enlarging, painful and locally inflamed neck mass. Computed tomography revealed multifocal lesions, the largest located in the left thyroid lobe, and suggested chronic thyroiditis. After five days of intravenous antibiotics and corticosteroids, the patient underwent a function-preserving left lobectomy. Definitive histopathology and immunohistochemistry established the diagnosis of PTL. Post-operative 18F-FDG PET/CT was used for staging and the disease was classified as stage IIE non-Hodgkin lymphoma. Conclusion: This case highlights that definitive diagnosis of PTL may be achieved only after lobectomy and underscores the value of a function-preserving approach. Although intra-operative frozen-section analysis failed to detect the lymphoma, it assisted in guiding the extent of resection.