Atypical Histiocytoid Cells and Multinucleated Giant Cells in Fine-Needle Aspiration Cytology of the Thyroid Predict Lymph Node Metastasis of Papillary Thyroid Carcinoma

Abstract

Preoperative detection of cervical lymph node metastasis in papillary thyroid carcinoma (PTC) is crucial for determining the surgical strategy to prevent locoregional recurrence of the disease. We identified the cytological predictors of lymph node metastasis in 222 consecutive patients with PTC using fine-needle aspiration cytology (FNAC) of the thyroid. Cervical lymph node metastases occurred in 99 (44.6%) of 222 PTC patients. Lymph node metastasis was significantly associated with tumor multifocality (p = 0.003), and high cellularity (p = 0.021), atypical histiocytoid cells (p < 0.001), and multinucleated giant cells (p < 0.001) in thyroid FNAC. The BRAF V600E mutation was marginally associated with lymph node metastasis (p = 0.054). Multivariate analysis revealed that atypical histiocytoid cells (odds ratio = 2.717; p = 0.001) and multinucleated giant cells (odds ratio = 3.070; p = 0.031) were independent predictors of lymph node metastasis in patients with PTC. In a subgroup analysis of 164 patients with microcarcinomas, atypical histiocytoid cells (odds ratio = 2.761; p = 0.005) was an independent predictor of lymph node metastasis. Cytological detection of atypical histiocytoid cells and multinucleated giant cells on thyroid FNAC can be used to preoperatively predict cervical lymph node metastasis in patients with PTC.

Keywords: fine needle aspiration; liquid-based preparation; lymph node metastasis; papillary carcinoma; thyroid cytopathology.

Figure 1

Cytologic features and corresponding histology of atypical histiocytoid tumor cells in papillary thyroid carcinoma (PTC). (a) Atypical histiocytoid tumor cells (arrows) contain abundant granular cytoplasm and lack the typical nuclear features of PTC (ThinPrep, Papanicolaou stain, ×400). (b) Atypical histiocytoid cells are clustered and show abundant and vacuolated cytoplasm (ThinPrep, Papanicolaou stain, ×400). (c) In a small cluster of atypical histiocytoid cells, a cell with abundant cytoplasm shows an intranuclear cytoplasmic pseudoinclusion (arrow) (ThinPrep, Papanicolaou stain, ×1000). (d) Corresponding histologic images reveal isolated or dyscohesive cells and micropapillary features (hematoxylin and eosin stain, ×400).

Figure 2

Cytologic features and corresponding histology of multinucleated giant cells in papillary thyroid carcinoma (PTC). (a and b) Multinucleated giant cells and tumor cells are seen in fine-needle aspiration of PTC. Multinucleated giant cells carry variable number of nuclei (ThinPrep, Papanicolaou stain, ×400). (c) Atypical histiocytoid cells (arrow) often accompany multinucleated giant cells (ThinPrep, Papanicolaou stain, ×400). (d) Corresponding histologic image shows a multinucleated giant cell (arrow) and dyscohesive tumor cells within the follicular space (hematoxylin and eosin stain, ×400).