Lymphoid tangles is a useful cytological feature in the diagnosis of Hashimoto thyroiditis

Abstract

INTRODUCTION: A cytological diagnosis of Hashimoto thyroiditis (HT) is made in the presence of Hurthle cells in a background of plasma cells and lymphocytes. The presence of lymphoid tangles as a diagnostic feature has been described only in isolated case reports. OBJECTIVE: To assess the value of lymphoid tangles in the cytological diagnosis of HT. DESIGN, SETTING AND METHODS: Forty one smears with an unequivocal cytological diagnosis of HT and 41 smears of colloid storing goitres (CSG) were selected. 10 high power fields of the most cellular smear were assessed for lymphoid tangles defined as haemotoxyline stained fibrillary material. The presence of lymphoid tangles were graded as Grade 0 - absence of tangles/10 hpf; Grade 1 - presence of tangles in <50% /lOhpf and Grade 2 - presence of tangles in >50% /lOhpf. The observer had no knowledge of the initial diagnosis. The likelihood ratio was calculated; those above 10 and below 0.1 considered as strong evidence for the presence or absence of disease respectively. RESULTS: In the 41 CSG smears, 33 (80.4%) showed no tangles and 8 (19.5%) showed grade 3 tangles. None of the smears showed grade 2 tangles. All 41 cases of HT revealed lymphoid tangles with 34 (82.9%) having grade 2 tangles and 7 (17%) grade 1 tangles. The likelihood ratio was 0.00, 0.85 and 34.0 respectively for Grade 0, Grade 1 and Grade 2 tangles. Grade2 lymphoid tangles were strongly predictive of a diagnosi s of HT. CONCLUSION: The presence of Grade 2 lymphoid tangles in the smears is a useful diagnostic feature in HT.