Endocrine Abstracts

Primary thyroid lymphoma accounts for <5% of thyroid malignancies. The most common (up to 70%) and clinically aggressive sub-type is non-Hodgkin’s B-cell lymphoma. Mucosa-associated lymphoid tissue (MALT) lymphoma is less common (up to 30%) and clinically more indolent. Females are more frequently affected than males (4-8:1) with onset in 6th and 7th decades. A strong association with Hashimoto’s disease (>90%) is recognised. A 66 year old male presented with an 18 month history of a painless, increasing in size anterior neck mass. He had also experienced hoarsening of voice for 10 months. Systemic symptoms were absent. Primary hypothyroidism had been diagnosed two years earlier and CT imaging of thorax, abdomen and pelvis (following minor trauma) coincidentally demonstrated the presence of an asymmetrical goitre, left lobe larger than the right, with tracheal deviation and retrosternal extension. Ten years earlier a CT pulmonary angiogram confirming pulmonary embolism coincidentally demonstrated normal appearance of thyroid. Treatment: thyroxine 75 mg od, bisoprolol 5 mg od and warfarin variable dose. Examination confirmed the presence of an asymmetric smooth goitre with left lobe larger than right. Investigations: fT4 12.5 pmo/l, fT3 4.6 pmo/l, TSH 3.86 mU/l, anti-TPO antibodies negative at 4.8 U/ml and lactate dehydrogenase slightly elevated at 398 U/l. CT imaging confirmed increased goitre size, minimal tracheal compression and suspicious left-sided cervical lymphadenopathy. The relatively rapid increase in size of the goitre, progressive hypothyroidism and negative anti-TPO antibodies led to suspicion of thyroid lymphoma. Ultrasound guided thyroid biopsy and lymph node FNA confirmed stage 2E MALT lymphoma. This case confirms the need for vigilance in cases of rapidly enlarging goitre and the diagnostic utility of biopsy. The negative serology suggests infiltration of thyroid tissue as possible aetiology of the hypothyroidism. Treatment of primary MALT lymphoma of thyroid remains controversial.