The incidence of ground glass nuclei in thyroid diseases.

Ground glass nuclei are an important finding in the diagnosis of papillary carcinoma of the thyroid. However, they appear only in specimens in paraffin-embedded histological sections, and not in frozen sections or cytological specimens. This has led to the conclusion that they are an artifact of fixation and/or embedding. However, if this is the case, a question arises as to whether or not such an artifact can be of value as a definitive sign for establishing a diagnosis of papillary carcinoma. This study was undertaken to try to answer that question. 1) To confirm whether or not the author's microscopic observations were correct, we carried out automatic imaging analysis with the Interaktives Bild-Analysen System (IBAS). The author's microscopic observations were consistent with the data obtained by the IBAS. 2) Among 20 cases of papillary carcinoma, clear nuclei were observed in 11 cases (55%), and pseudoclear nuclei were noted in 20 cases (100%). When 1,000 papillary cancer cells were counted in 10 cases, the average incidences of clear nuclei and pseudoclear nuclei were found to be 0.51% and 18.3% respectively. Clear nuclei were seen in papillary carcinomas in all kinds of fixatives except one but were not seen in benign lesions. Even though ground glass nuclei are a type of artifact, we believe that their presence may be considered to be a characteristic feature of papillary carcinomas of the thyroid.