Occult papillary carcinoma of the thyroid. A “normal” finding in finland. A systematic autopsy study

Abstract

The thyroids from 101 consecutive autopsies from Finland were subserially sectioned at 2-to 3-mm intervals. From 36 thyroids, 52 foci of occult papillary carcinoma (O K) were found, giving a prevalence rate of 35.6%. the highest reported rate in the world. The rate was higher, although not significantly, in males (43.3%) than in females (27.1%), but it did not correlate to the age of the patients. Twenty-six glands contained one tumor focus and ten glands contained two to five tumor foci. Only a minority of the smallest tumors can be detected with the method used. The probable number of O K s over 0.15 mm in diameter was calculated to be about 300 in this material. The tumor diameter varied from 0.15 mm to 14.0 mm, with 67% of tumors under 1.0 mm. The smallest tumors were usually circumscribed and were composed almost solely of follicles. Imrger tumors had more papillary structures and were often invasive. Fibrosis and, in the largest O K s , lymphocytic reaction were seen around the invasive islands. All tumors were positively stained for thyroglohulin and all but one of the tumors stained positively for epidermal keratin. OPC appears to arise from follicular cells of normal follicles. Apparently the great majority of the tumors remain small and circumscribed and even from those few tumors that grow larger and become invasive O K s only a minimal proportion will ever become a clinical carcinoma. According to the study, OPC can be regarded a s a normal finding which should not be treated when incidentally found. In order to avoid unnecessary operations it is suggested that incidentally found small O K s (less than 5 mm in diameter) were called occult papillary tumor instead of iarcinoma. Cuncer 56531-538, 1985. HYROID CARCINOMA is not a common disease; its T incidence rates range in different countries from 0.5 to 10 per lo5 persons.' In most countries, papillary carcinoma is the most common histologic type that comprises about 40% to 70% of all cases.'-5 Its incidence rates in the Scandinavian countries vary between 0.4 and 3.4 per 10' persons.6 Although papillary carcinoma is not common compared to many other human cancers, the prevalence rate of occult papillary carcinoma (O K) has been reported to be high, varying between 5.6% and 28.4% in several systematical autopsy studies.'-' '

High Prevalence of Carcinoma in Ultrasonography-guided Fine Needle Aspiration Cytology of Thyroid Nodules

“…The majority of PMCs are not palpable and so clinically unapparent. In the past, many PMCs were found on pathology specimens from thyroid gland removed for benign thyroid diseases, such as Graves' disease, multinodular goiter, and hyperthyroidism or on autopsy of patients who had died of nonthyroid-related diseases [22][23][24][25]. However, in recent years there has been a considerable increase in the preoperative diagnosis and so in the relative rate of PMC [26][27][28].…”

Approach to Metastatic Carcinoma of Unknown Primary in the Head and Neck: Squamous Cell Carcinoma and Beyond

“…On the other hand (although data is relatively limited), incidental PTC in neck lymph nodes appears to be extremely indolent. It is well known that there is a significant incidence (up to 35 %, if the thyroid gland is thoroughly examined histologically) of occult PTC in the general population identified in autopsy studies [31]. Therefore, it is not surprising that metastatic PTC is occasionally encountered incidentally in neck dissections performed for other reasons, most commonly for head and neck SCC.…”

Diagnostic Value of Ultrasound-Guided Fine Needle Aspiration Biopsy in Malignant Thyroid Nodules: Utility for Micronodules

“…These are two important clinical features, and the nodules are non-palpable, therefore difficult to detect on physical examination. The studies in autopsy series report a 0.5-5.2% occurrence rate for latent PTMC measuring between 3 mm and 9.9 mm in diameter (Fukunaga et al, 1975;Harach et al, 1985;Samson RJ, 1977). Ultrasonographic examination and FNAB become more important in such circumstances.…”