Primary thyroid lymphoma accounts for only 2–5% of all thyroid tumors and primary Burkitt’s lymphoma of the thyroid is even less common than the other types of B-cell lymphoma. It is a highly aggressive non-Hodgkin’s lymphoma characterized by intermediate-sized lymphoid cells with a “starry sky” appearance and exhibits chromosomal translocations that activate the MYC oncogene. A male predominance and an aggressive clinical course with a high risk of CNS involvement and tumor lysis syndrome are all well-recognized features of Burkitt lymphoma. We present a case of a 28-years-old man with primary Burkitt's lymphoma of the thyroid masquerading as post-COVID thyroiditis.

Clinical case: A 28-year-old Thai man without history of thyroid disease, immunodeficiency, or prior malignancy presented with anterior neck pain with enlarging thyroid goiter for 2 months after mild COVID-19 infection. He had been found to have multiple nodular goiters at time of neck pain and subacute thyroiditis had been diagnosed from a local clinic. However, he presented at our hospital with a rapidly enlarging neck mass with estimated thyroid size 60 grams. Laboratory investigations showed normal thyroid function test with positive anti-thyroglobulin antibody. Ultrasound revealed conglomerated hypoechoic mass both lobes with multiple enlarged right cervical lymph nodes. Core needle biopsy showed round; intermediate sized lymphoid cells admixed with scattered tingible body macrophages imparting a “starry sky” appearance. Hashimoto’s thyroiditis was identified in the non-tumoral thyroid tissue. The presence of MYC rearrangement using fluorescence in situ hybridization was confirmed.

Following the final histological diagnosis of primary thyroid Burkitt’s lymphoma, the patient received rituximab, cyclophosphamides, doxorubicin, and dexamethasone (R-Hyper-CVAD). The CT chest-abdomen-pelvis protocol showed no distant metastasis. However, lymphoma cells were found in cerebrospinal fluid through lumbar puncture. Six months after the diagnosis, the patient expired from disease progression causing upper airway obstruction.

Primary Burkitt lymphoma of the thyroid can cause pain and other symptoms due to the rapidly growing mass in the neck. The clinical course is aggressive with a high frequency of disseminated disease at diagnosis. Adequate pathological diagnosis with core needle biopsy rather than FNA is essential for treatment planning and outcome improvement.