Fine Needle Aspiration Cytology of Postoperative Spindle Cell Nodule in Neck after Thyroidectomy: A Case Report
A 53-year-old female patient visited the hospital for evaluation of an asymptomatic right lateral neck mass. She had undergone a right thyroid lobectomy for treatment of a papillary microcarcinoma 22 months prior. The tumor measured 0.7×0.6 cm in size with a clear resection margin. After the operation, she was followed regularly, and there were no events.\nA hypoechoic mass with multiple calcifications was observed on thyroid ultrasonography, and ultrasonography guided-FNA was performed. The smear of the FNA cytology showed fragments of fibrocollagenous connective tissue and scattered spindle cells (). Some histiocyte-like cells were aggregated forming vague granulomas (). Loosely scattered young fibroblast-like cells with plump nuclei were observed (). The cytologic diagnoses were suggestive of nodular fasciitis or a granulomatous reaction to a foreign body.\nThe patient had undergone a complete thyroidectomy and neck mass excision. Severe adhesions were observed in the postoperative thyroid bed, and the residual thyroid left lobe was normal in appearance on gross examination.\nGrossly, the neck mass measured 4.3×3.5×2.6 cm, with a round, firm, and whitish surface. The cut surface was a homogenous yellow-tan color and was focally hemorrhagic (). There were no pathologic findings in the thyroid left lobe.\nMicroscopically, the mass was found to be composed of bland-looking spindle cells (), with an indistinct cell border, eosinophilic cytoplasm, and oval nuclei. The nucleoli were inconspicuous (). Mitotic counts were 6 per 10 high power field without atypism (, inset). Adhesions on adjacent structures were observed, but did not show an infiltrative pattern.\nThe spindle cells were fully reactive in vimentin (prediluted, V9, Dako, Glostrup, Denmark) and focally positive for α-smooth muscle actin (prediluted, 1A4, Dako); however, they were negative for anaplastic lymphoma kinase (ALK; 1 : 50, ALK1, Dako), Cam 5.2 (prediluted, Becton Dickinson, CA, USA), desmin (prediluted, D3, Dako), epithelial membrane antigen (prediluted, E29, Dako), and pancytokeratin (prediluted, AE1/AE3, Dako) (). Ki-67 labeling index was less than 5%.