Black thyroid: a pitfall for aspiration cytology

Black thyroid revisited: cytologic diagnosis in fine-needle aspirates is unlikely

We report four patients diagnosed with black discoloration of the thyroid gland at surgery and a fifth patient in which the "black thyroid" was an incidental finding at autopsy. The four patients diagnosed at surgery had prior fine-needle aspirations (FNA), which did not reveal any characteristic pigmentation. One patient presented with cervical lymph node metastases from a papillary microcarcinoma of thyroid. The second patient was diagnosed as a cellular adenomatoid nodule, and suppressive therapy was recommended. She elected to have surgery instead. The third patient underwent surgery because of an oxyphilic cell nodule, in a background of lymphocytic thyroiditis, in which a Hürthle cell neoplasm could not be ruled out. His aspirates were reviewed at two other institutions, and no diagnosis of black thyroid was entertained. The fourth patient had an adenomatoid nodule with cystic change and slightly atypical squamous metaplasia. She decided to have surgery, which revealed a black thyroid. Later, it was discovered that the patients had received minocycline for the treatment of acne. FNA does not seem to be a reliable method to diagnose black thyroid preoperatively. Although this is a striking operative finding, diagnosing it on FNA seems to be unlikely and also inconsequential.

Cytology of the thyroid gland: pitfalls in aspiration of the fibrotic nodule

Fibrotic changes can be found in a variety of pathologic processes that affect the thyroid gland, and yet fine-needle aspiration (FNA) correlation of these lesions is not well-known. Cytologic findings are described from three different lesions, all with extensive fibrosis, that occurred in thyroid gland FNA. In each case, fibrotic changes resulted in cytologic changes potentially representing pitfalls in aspiration diagnosis. FNA revealed, solely or predominantly, fibroblasts in 2 patients whose subsequent thyroidectomies disclosed diffusely sclerotic papillary carcinoma and multinodular goiter. In the third case, an initially suspicious FNA was followed by multiple unsuccessful attempts at a second FNA. At thyroidectomy, a follicular adenoma with post-FNA fibrosis and infarction was identified. The differential diagnoses in thyroid FNA of fibrotic nodules can be broad, and this is discussed. Awareness of potential pitfalls may improve diagnostic accuracy.