Renal cell carcinoma metastatic to follicular adenoma of the thyroid gland. A case report

BACKGROUND: Renal cell carcinoma is an unpredictable tumor that can recur many years after the original diagnosis and metastasize to uncommon sites, including the thyroid gland. Differential diagnosis from primary thyroid tumor is often difficult both clinically and pathologically. We report a case of metastatic renal cell carcinoma in follicular adenoma of the thyroid gland. CASE: A 48-year-old woman presented with a 3-cm-diameter, palpable mass in the left lobe of the thyroid gland. The patient's history included removal of a left renal mass, which was conventional renal cell carcinoma. Fine needle aspiration cytology smears contained a few small clusters of polygonal cells with abundant, clear cytoplasm and irregular, hyperchromatic nuclei as well as bland-looking thyroid follicle cells and stromal cells. A papillary or follicular growth pattern was not detected. A cell block made from the aspirated sample was composed mainly of clear cells. By immunohistochemical stains, the clear cells were completely negative for TTF-1, thyroglobulin, calcitonin and inhibin while equivocally staining for cytokeratin, CD10 and galectin-3. The histologic diagnosis was renal cell carcinoma metastatic to follicular adenoma of the thyroid gland. CONCLUSION: Renal cell carcinoma metastatic to the thyroid may masquerade as a primary thyroid neoplasm. A history of prior nephrectomy, the presence of unremarkable thyroid follicle cells, the absence of a papillary or follicular growth pattern and immunohistochemical study can help differentiating metastatic renal cell carcinoma from a primary thyroid lesion with clear cell change.     

Planimetric studies on fine needle aspirates from follicular adenoma and follicular carcinoma of the thyroid

A planimetric study was performed on fine needle aspiration biopsy smears from 21 follicular thyroid adenomas, 13 follicular thyroid carcinomas and 7 nontoxic goiters. The nuclear and the cytoplasmic projected areas were measured in each smear on 50 cells with intact nuclei. The nuclear-cytoplasmic area was calculated. Significant differences in mean nuclear area were found between benign and malignant follicular neoplasms and between neoplastic cells and cells from nontoxic goiter. Planimetry of cells aspirated from follicular neoplasms permitted differentiation between carcinomas and adenomas with a high degree of statistical probability.     

Pituitary metastasis of follicular thyroid carcinoma

OBJECTIVE: The case of a 60-year-old male patient with follicular thyroid cancer who developed a pituitary mass proved to be a metastasis from thyroid cancer. METHODS: Assessment with whole-body scan, ultrasound, computed tomography and thyroglobulin measurements. RESULTS: Despite surgery and repeated doses of radioiodine, the patient developed diplopia and ptosis of the right eyelid, along with increasing thyroglobulin levels. A pituitary mass was discovered, with no signs of pituitary deficiency. The mass was removed and found to consist of neoplastic cells immunohistochemically positive to thyroglobulin. CONCLUSIONS: Distant metastases may develop in cases of follicular thyroid carcinoma, even after repeated doses of (131)I. Metastatic follicular thyroid carcinoma to the pituitary is a rare entity.     

Ultrastructural pathology of the thyroid folliculo-papillary and follicular carcinoma

Twenty cases of thyroid carcinoma (10 follicular and 10 folliculo-papillary) were ultrastructurally studied. In the follicular carcinoma the most striking features were: microfollicular cavities with microvilli from the apical surface of the tumorous cells, intracellular microlumens, swollen mitochondria sometimes containing electrondense bodies and tightly packed filaments. In the solid sheaths light and dark cells were present. Golgi complexes were disposed in small dense cristae. The nuclei were large, round, oval or with a folded appearance. In the folliculo-papillary carcinoma were found nuclei with an irregular shape containing stage I and stage II inclusions, dilated endoplasmic sacks, closely packed, sometimes dystrophic mitochondria, dense bodies or tightly packed parallel filaments and numerous phagolysosomes. The peroxidase activity wa present as black precipitates in the nuclear envelope or around colloid droplets. The acid phosphatase activity was found as unhomogeneous precipitates inside the lysosomes. From this study it could be concluded that the follicular and folliculo-papillary carcinomas have some common ultrastructural features; the ultrastructural and cytoenzymological patterns suggest marked alteration of the synthesis, storage and secretion of thyroid hormones.     

Karyometric marker features in fine needle aspirates of follicular adenoma of the thyroid

Karyometric measurements were performed on fine needle aspirates of clearly identifiable adenomatous areas and adjacent normal-appearing areas in the surgical specimens from ten patients with follicular adenomas of the thyroid. Similar measurements were made on aspirates from nine patients free of thyroid disease. A total of 95 karyometric features were evaluated for each nucleus. Analysis of variance of optical density values did not show a significant difference between the three types of nuclei. Discriminant analysis selected seven karyometric features that produced a statistically highly significant separation of adenoma nuclei from control nuclei. A similar analysis selected six features that produced a statistically highly significant discrimination of normal-appearing nuclei from control nuclei. The validity of these markers for distinguishing control nuclei from adenoma nuclei and normal-appearing nuclei adjacent to adenomas was demonstrated by analysis in further training and test sets. These findings parallel those previously demonstrated for invasive and microinvasive follicular carcinomas of the thyroid.     

Desmosomes of follicular cells and C-cells in the thyroid gland of rats]

Well developed desmosomes can be seen between the C-cells and follicular cells in the rat thyroid gland. They are structurally similar to the desmosomes at the boundaries of homotypic cells. This observation speaks in favour of the development of C-cells from the initial cells of thyroid embryonic analage.     

Spontaneous thyroid follicular adenoma in a laboratory mouse (Mus musculus)

Spontaneous thyroid micro-follicular adenoma was found in an 18-month-old nursing Swiss albino mouse. The lesion was first noted as a tiny bulge at the base of the neck. The tumor was solid, and within two months, had grown such an enormous size that movement, feeding and suckling of the litter were greatly hampered. The litter of seven mice later died due to improper nursing while their mother remained generally unaffected by the mass.     

Down regulation of hypertrophied follicular cell volume in thyroid hyperplastic gland

In the present study, changes in thyroid follicular cell volume and its regulation have been investigated during the early involution of a hyperplastic goitre. Male Wistar rats were administered an iodine deficient diet for 6 months with propylthiouracil (PTU, 0.15%) during the last two months. At the end of iodine deficiency (day 0), some rats were killed and the others received a normal iodine diet. These rats were killed after different periods of iodine refeeding. Thyroid follicular cell volume was very high in hyperplastic gland whereas thyroid protein concentration was low. Thyroid follicular cell volume quickly decreased when rats were normally iodine refed, whereas thyroid protein concentration increased. Electron microscopal observations showed that thyroid follicular cells retained their endocrine aspect in hyperplastic state and throughout the iodine refeeding period. Using concomitant stereological and biochemical techniques, it is shown that the amount of cellular iodide and an unknown iodinated compound strongly increased during the early iodine refeeding. Plasma TSH was high on day 0 and remained at this level until day 8 whereas plasma T3 and T4 were low on day 0 and remained at this low level until day 4. The present data show that the involution of thyroid follicular cell volume is induced by iodide and mediated by an iodinated compound at least in the initial phase, and is independent of plasma TSH, T3, T4, so indicating the involvement of a thyroid autoregulatory mechanism. These changes in cell volume may be of importance in ion transport, i.e. in the metabolism of thyroid follicular cell during the early involution of the hyperplastic goitre.     

Fine needle aspirates of follicular lesions of the thyroid gland. The intermediate-type smear

In order to evaluate fine needle aspirates of thyroid lesions with features intermediate between those of follicular neoplasms and colloid nodules, 38 aspirates in which a definitive diagnosis had not been made were reviewed. On review, ten aspirates were excluded from the "intermediate" category; seven were reclassified as unsatisfactory and one as a cellular colloid nodule. Two papillary carcinomas showed a complex pattern not identified in smears from other lesions; these aspirates were also classified separately for independent evaluation. The remaining 28 aspirates were characterized by syncytial-type tissue fragments with mild nuclear atypia. The association of syncytial-type tissue fragments and orderly sheets and fragments forming a honeycomb pattern in the same aspirate indicated a colloid nodule, though a two-disease process could not be excluded. Of the aspirates containing only syncytial-type tissue fragments, 50% were from adenomas, 25% were from carcinomas, and 25% were from colloid nodules. Criteria to distinguish between the various follicular lesions were not identified in these smears.     

Unusual spread of the follicular thyroid carcinoma,metastases to liver and pancreas

We report a multimetastatic follicular thyroid carcinoma(FTC) with match lesions between ¹⁸F-FDG PET/CT and post-treatment ¹³¹I imaging. The patient had a history of thoracic vertebra corpectomy surgery and liver tru-cut biopsy; both resulted in metastases of FTC. After total thyroidectomy surgery, the patient was referred to the ¹⁸F-FDG PET/CT to investigate other possible metastatic foci. ¹⁸F-FDG PET/CT showed increased FDG uptakes on a cervical lymph node, bones, lung, liver, and pancreas. After treatment of ¹³¹I, post-treatment iodine scintigraphy demonstrated iodine uptakes in the same areas as the ¹⁸F-FDG PET/CT scan and at the thyroid bed. All the matched lesions were concluded as a spread of the FTC. Here we describe an infrequent differentiated thyroid carcinoma case with metastases to the liver and pancreas. This case report also highlights the importance of ¹⁸F-FDG PET/CT in determining the extent of thyroid cancer.