Primary Thyroid Lymphoma: Could Surgery Be Avoided

Background: Primary thyroid lymphoma is a rare thyroid disease that makes up only 1 to 5% of all thyroid oncological disorders. The average patient with primary thyroid lymphoma is a woman in her sixth or seventh decade with a history of Hashimoto’s thyroiditis. Clinical Case: 28-year-old woman complained of hoarseness, rapidly enlarging mass of the neck. She was referred to an otorhinolaryngologist by her family physician who suspected upper airway pathology. Otorhinolaryngologist observed swelling of patients’ larynx and prescribed treatment for suspected bacterial larynx infection. Symptoms kept worsening despite of treatment and patient was referred to an endocrinologist for a consultation. Blood lab tests were unremarkable. Ultrasound of the thyroid was performed which revealed a large (4,5 cm), hypoechoic, solid, homogenous node with Doppler signs of increased intranodular vascularity. Additionally, enlarged submandibular salivary gland lymph nodes on both sides of the neck were observed. FNAC (fine-needle aspiration cytology) was performed to diagnose possible thyroid malignancy, however findings showed atypia of undetermined significance (3rd category of Bethesda classification), to differentiate from lymphocytic thyroiditis. Because of high risk of malignancy, it was decided to perform thyroidectomy. During surgery, urgent intraoperative biopsy revealed undifferentiated thyroid carcinoma. As radical tumor extirpation due to prominent surrounding fibrosis was impossible, then only one side lobectomy was performed. Final histological examination revealed large B cell lymphoma, phenotype: CD20+, BCL6+, MuM1+, CD21+, cMyc-, BCL2-, CD10-, CD30-, Ki-67 up to 97%. More accurate disease staging was performed post-operatively, PET scan and computed tomography revealed disseminated primary thyroid lymphoma. Final diagnosis was Stage IV primary large B cell lymphoma of the thyroid. Patient was treated with chemotherapy according to Rx7-CHOP14x6 (Rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) protocol. The treatment was tolerated well, 3 months after, complete remission of the disease was observed. During outpatient visits patient remained in remission for all 5 years of planned regular check-ups. Conclusion: This case demonstrates the diagnostic challenge of primary thyroid lymphoma. In the presence of rapidly enlarging thyroid mass, thyroid lymphoma is not usually suspected. FNAC as golden standard of thyroid malignancy often does not allow differentiation of this pathology. In this case, a core biopsy could have helped to make correct preoperative diagnosis and to avoid unnecessary surgery.