Occult carcinoma of the thyroid. A systematic autopsy study from Spain of two series performed with two different methods

Abstract

Background. Occult carcinoma of the thyroid (OCT) seems to be present in a significant proportion of the general population. Previous studies have shown large variations in the prevalence rate of OCT, which may be due to differences in the prevalence rates between different geographic areas, but also to the lack of standardized diagnostic criteria and methods of examination. The epidemiologic features of OCT at autopsy in Spain are reported for the first time. Methods. To investigate the influence of methodology in the results, two series were studied, each one using a different method. In Series A, 625 cases were studied, and sections were taken only from grossly visible lesions. In Series B, the whole thyroid glands of 100 autopsies were cut into blocks and all blocks were histologically studied. In addition, immunocytochemical stainings were performed in Series B for calcitonin, thyroglobulin, and epidermal keratin. Results. Series A found 33 OCTs (5.28%), consisting of 29 occult papillary carcinomas (OPC), 2 occult follicular carcinomas, 1 occult oxyphilic carcinoma, and 1 occult medullary carcinoma. Series B found 22 OPC cases (22%) containing a total of 53 tumor foci. Tumor diameter varied from 0.07 to 1.8 mm. The epithelial cells of all the OPC were negative for calcitonin, weakly positive for thyroglobulin, and intensely positive for epidermal keratin. One case had metastasis in a regional lymph node. Conclusions. This study shows that the differences in the incidence of OCT found in numerous studies are due not only to actual different geographic incidences but also to the method of study.

Papillary Thyroid Carcinoma with Primary Hyperparathyroidism: A Report of Two Cases and a Brief Literature Review

“…However, neither of our patients had any history of radiotherapy. The incidence of thyroid microcarcinoma in large autopsy series (5.3%-6.2%) (21,22) is similar to the PTC incidence cited in the large surgical series above (5)(6)(7)(8)(9)(10). This also suggests that the occurrence of these two diseases together in single individuals is a matter of coincidence.…”

Papillary Thyroid Microcarcinoma - Own Experience

“…One study compared the frequency of microcarcinoma diagnosis during examination of the removed goiter by means of two different methods. The examination of the selected and macroscopically suspected areas revealed 5.8% frequency, while the examination of the successive sections of slices cut every 2-3 mm revealed 22% frequency (9). The frequency of microcarcinoma diagnosis among patients with thyroid carcinoma may exceed 50%.…”

Thyroid Carcinomas Found Incidentally in the Cervical Lymph Nodes: Do They Arise From Heterotopic Thyroid Tissues?

“…We reviewed the incidental thyroid carcinomas formed in the cervical lymph nodes and added the frequency of the existence of primary occult carcinomas in the thyroid glands (Table 3) suspicious cases of occult metastasis and they ascertained the existence of thyroid gland carcinomas in 5 of these cases. In addition, some autopsy reports showed occult thyroid gland carcinomas, 14,15) which indicated a high percentage of occult carcinomas. However, as we have described above, nearly two-fifths of patients with incidental thyroid carcinoma in the cervical lymph nodes, including the cases of Attie JN et al 12 did not have thyroid gland carcinoma.…”

“…In fact, small thyroid carcinomas (occult carcinomas) were detected not only in cervical lymph nodes but also in the thyroid glands obtained from surgically removed tissues and autopsied bodies. [11][12][13][14][15] Do these reports, however, support a hypothesis that incidental thyroid carcinomas found in the lymph nodes are fully indicative of the occult metastasis of the thyroid carcinoma without any exception?…”