The Usefulness of Immunocytochemistry of CD56 in Determining Malignancy from Indeterminate Thyroid Fine-Needle Aspiration Cytology

The Usefulness of Immunocytochemistry of CD56 in Determining Malignancy from Indeterminate Thyroid Fine-Needle Aspiration Cytology

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Background Fine-needle aspiration cytology serves as a safe, economical tool in evaluating thyroid nodules.However, about 30% of the samples are categorized as indeterminate.Hence, many immunocytochemistry markers have been studied, but there has not been a single outstanding marker.We studied the efficacy of CD56 with human bone marrow endothelial cell marker-1 (HBME-1) in diagnosis in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) category III.Methods We reviewed ThinPrep liquid-based cytology (LBC) samples with Papanicolaou stain from July 1 to December 31, 2016 (2,195 cases) and selected TBSRTC category III cases (n = 363).

Twenty-six cases were histologically confirmed as benign (six cases, 23%) or malignant (20 cases, 77%); we stained 26 LBC slides with HBME-1 and CD56 through the cell transfer method.For evaluation of reactivity of immunocytochemistry, we chose atypical follicular cell clusters.Results CD56 was not reactive Eternal Ink Muted Earth Colours in 18 of 20 cases (90%) of malignant nodules and showed cytoplasmic positivity in five of six cases (83%) of benign nodules.CD56 showed high sensitivity (90.0%) and relatively low specificity (83.

3%) in detecting malignancy (p =.004).HBME-1 was reactive in 17 of 20 cases (85%) Trimmers of malignant nodules and was not reactive in five of six cases (83%) of benign nodules.HBME-1 showed slightly lower sensitivity (85.0%) than CD56.

The specificity in detecting malignancy by HBME-1 was similar to that of CD56 (83.3%, p =.008).CD56 and HBME-1 tests combined showed lower sensitivity (75.0% vs 90%) and higher specificity (93.

8% vs 83.3%) in detecting malignancy compared to using CD56 alone.Conclusions Using CD56 alone showed relatively low specificity despite high sensitivity for detecting malignancy.Combining CD56 with HBME-1 could increase the specificity.Thus, we suggest that CD56 could be a useful preoperative marker for differential diagnosis of TBSRTC category III samples.