The fine structure of papillary carcinoma of the thyroid

Application of Fractal and Euclidean Methods to Differentiate Normal and Neoplastic Thyroid Cells

Context: The differentiated papillary and follicular thyroid neoplasms can be characterized from the notions of fractal and Euclidean geometry to overcome the challenges faced by the pathologist. This method was previously used in differentiating preinvasive lesions of cervical cancer. Aims: to characterize the irregularity of histologic samples of normal thyroid cells as well as benign and malignant thyroid papillary and follicular carcinomas, through the box-counting method using the principles of fractal and Euclidian geometry. Settings and Design: This is a retrospective study involving the measurement of thyroid cells through pixels in photographs, applying geometric methods. Subjects and Methods: Photographs of histological samples from normal and neoplastic biopsy samples were taken and processed by a software in order to delimit the borders of the nucleus and cytoplasm. Then, the box-counting method was applied by superimposing grids of 5 and 10 pixels to measure the fractal dimension and the occupied spaces of the cellular surface. Results: The set of papillary and follicular cells evaluated from the occupied spaces from the borders and surfaces of the nucleus and cytoplasm in the 5-pixel grid showed that normal cells are included within a range of values, while the neoplastic variations are differentiable from this range. Conclusions: Fractal and Euclidean geometries can differentiate normality from some benign and malignant thyroid lesions, which opens a path to develop methodologies that characterize more precisely distinctive features between normal and neoplastic cells independent of qualitative criteria from traditional pathology and histology.

Cytological, histological and ultrastructural nuclear features of monster cells in a canine carotid body carcinoma

A 7-year-old female Shih-tzu dog was presented with severe dyspnoea. A large mass was palpated in the left cranial neck. Cytological examination of an aspirate sample revealed cells with marked anisokaryosis, giant elements and many bare nuclei. Scattered intact giant cells showed scant, granular cytoplasm and intranuclear inclusions. Histologically, neoplastic cells were subdivided into lobules by fine collagenous trabeculae. Numerous pleomorphic giant, or 'monster', cells were observed, showing a highly indented nuclear envelope, intranuclear cytoplasmic pseudoinclusions (ICPs) and 'ground-glass' nuclear appearance. Neoplastic emboli were present, but no distant metastases were detected grossly. Immunohistochemically, the neoplastic cells expressed synaptophysin and had variable expression of neuron-specific enolase and vimentin. The cells were negative for pan-cytokeratin, CAM 5.2, glial fibrillary acidic protein and S100. Nuclear abnormalities and cytoplasmic neurosecretory granules were noted ultrastructurally. These features were consistent with a diagnosis of carotid body carcinoma (chemodectoma). Monster cells with ICPs have not been documented previously in canine chemodectoma.

Nuclear grooves in fine-needle aspiration biopsies of breast lesions: do they have any significance?

Nuclear grooving is a recognized morphologic feature frequently seen in papillary carcinoma of the thyroid. This feature is also occasionally seen in other nonneoplastic and neoplastic conditions. Nuclear grooves have been described in tubular carcinoma of the breast. However, the significance of nuclear grooves in benign and malignant conditions of the breast has been rarely studied. In a retrospective study, we searched for the presence of nuclear grooves in Papanicolaou-stained and Diff-Quik-stained fine-needle aspiration biopsies (FNAB) of 50 cases of primary breast carcinomas, 25 cases of proliferative breast disease, and 25 cases of fibroadenoma. In addition, 10 cases of metastatic breast carcinoma diagnosed by FNAB were reviewed. Nuclear grooves were identified in 39 of 50 (78%) of the histologically confirmed primary breast carcinomas and in 9 of 10 (90%) of the cases of metastatic breast carcinomas in the Papanicolaou-stained smears. Nineteen of 50 (38%) of the cases of proliferative breast disease/fibroadenoma showed nuclear grooves in the Papanicolaou-stained smears. The difference between the percentage of cases showing nuclear grooves seen in the Papanicolaou-stained primary breast carcinomas and metastatic breast carcinomas compared with the benign breast lesions was statistically significant (P < 0.001 in the primary breast carcinoma cases and P < 0.01 in the metastatic breast cancer cases). Nuclear grooves were identified less often in the Diff-Quik-stained smears, and their presence in malignant lesions versus cases diagnosed as benign breast disease was not statistically significant. This study suggests that although the presence of nuclear grooves is more frequently seen in malignant breast lesions, their presence cannot totally exclude the possibility of benign breast disease. The presence of nuclear grooves, however, may serve as a diagnostic clue in metastatic tumors of unknown primary.

Ultrastructural, cytochemical, and immunocytochemical study of nuclei and cytoskeleton of thyroid papillary carcinoma cells

One of the most constant and typical histological markers of thyroid papillary carcinoma is the presence of multilobated and ground-glass nuclei. With the intention of extending and characterizing the ultrastructural comprehension of this feature, thyroid papillary carcinoma cells and normal follicular cells were studied using chromatin and ribonucleoprotein preferential staining techniques, as well as immunolabeling with antibodies against DNA, lamins, vimentin, and desmin. Carcinoma cells showed scant compact chromatin arranged in small masses. A special type of nuclear bodies with DNA immunoreactive fibrils was found in these cells. Some nucleoli were surrounded by a double fibrillar layer limiting a perinucleolar space occupied by RNP fibrogranular structures that differed from those of normal nuclei. Perichromatin granules were scarce compared to normal follicular cells. Immunoelectron microscopic studies of lamins showed diminished immunoreactivity in the nuclei of carcinoma cells. A perinuclear distribution of desmin and vimentin filament was found in tumor cells. The cytoplasm of normal follicular cells showed scarce immunoreactivity to vimentin and no immunolabeling for desmin. Both types of filaments attach to the nuclear pore complex and to other regions of the nuclear envelope. Contacts between labeled filaments and desmosomes or hemidesmosomes were frequent. The results show that in papillary thyroid carcinoma cells, changes in the distribution of chromatin and ribonucleoproteins, either alone or in conjunction with scarce lamin immunolabeling and perinuclear vimentin and desmin filamentous rings, may be responsible for the characteristic ground glass and multilobated nuclei.

CD44 immunostaining of thyroid fine-needle aspirates differentiates thyroid papillary carcinoma from other lesions with nuclear grooves and inclusions

BACKGROUND

Although nuclear grooves and inclusions are considered to be characteristic cytologic features of thyroid papillary carcinoma, a variety of other thyroid lesions may on occasion display these features in fine-needle aspiration specimens.

METHODS

The authors evaluated the immunocytochemical staining of 16 fine-needle aspirations of thyroid papillary carcinoma and 14 aspirations of thyroid lesions confirmed to be other than papillary carcinoma but that included cells with nuclear grooving and/or inclusions, comprised of multinodular goiter (four cases), follicular adenoma (two cases), Hurthle cell adenoma (two cases), pure thyroiditis (three cases), and thyroiditis with nodular hyperplasia (three cases). CD44 previously has been shown to be selectively expressed in thyroid papillary carcinoma.

RESULTS

Of 16 surgically confirmed cases of thyroid papillary carcinoma featuring nuclear grooves and inclusions on fine-needle aspiration, 14 (88%) stained intensely for CD44 in a membranous pattern. Of the 14 nonpapillary thyroid carcinoma cases, only 1 (7%), a Hürthle cell adenoma, featured membranous CD44 staining. The difference in the proportion of cases with CD44 staining between the two groups was statistically significant (chi-square test, P < 0.001).

CONCLUSIONS

The authors conclude that immunostaining for CD44 can readily be performed on thyroid fine-needle aspiration specimens and that, for specimens featuring nuclear grooves and inclusions, the presence or absence of staining for CD44 may be of value in the distinction between thyroid papillary carcinoma and other lesions that may share some of the cytologic features of papillary carcinoma.

The epitheliomeral concept of the thyroid gland's structural organization

BACKGROUND

The permanent increase in the number of cases of different forms of thyroid pathology requires a deeper study of the thyroid structure and its morphogenetic processes.

METHODS

The thyroid glands of Wistar rats were used in a composite study that involved standard light microscopy, semithin sections, silver staining, immunohistochemistry, morphometry, three-dimensional analysis, and computer-assisted three-dimensional reconstruction.

RESULTS

The absolute majority of follicles have from one to seven interfollicular contacts (C) with other neighbouring follicles. The surface of C makes up 32% of the follicular basal surface. In the central zone of 1-micron-thick sections, the relative quantity of C per follicle (0.44 +/- 0.05) is 36% more than in the peripheral zone (0.28 +/- 0.07; P < 0.05). The analysis of serial sections shows that 134 follicles have 133 C. Only three follicles are separate; four form pair groups, and others form groups that include up to 92 follicles. Follicles form linear chains with numerous branches. A three-dimensional reconstruction demonstrates a spatial configuration of the parenchyma's elements. In C, the basement membrane is absent. Consequently, a group of interconnected follicles form a parenchymal compartment with a common basement membrane. We named these parenchymal compartments "epitheliomers." Both the formation of new follicles and follicular fusion take place within the boundaries of the epitheliomer without violating the integrity of the compartment. The fusion of follicles is brought on by the destruction of the epithelium of C.

CONCLUSIONS

The authors put forward a new "epitheliomeral" concept with regard to the structural organization of the thyroid gland.

Fine-needle aspiration biopsy of papillary thyroid carcinoma: cytologic, histologic, and ultrastructural correlations

Aspiration smears from a series of 21 papillary thyroid carcinomas were studied and a number of morphologic features correlated with the histologic and ultrastructural patterns. These included types of papillary structures, metaplastic cells, grooved and lobulated nuclei, optically clear nuclei, intranuclear inclusions, and macrophages. Generally there was a close correlation between histologic and cytologic findings. The numbers of macrophages and metaplastic cells appeared to be exaggerated in aspiration smears as compared with those seen on histologic sections. Optically clear nuclei were not seen on the air-dried cytologic smears. Grooved nuclei were somewhat difficult to recognize in the aspiration smears, although lobulated nuclei were identified easily. We consider the latter to be a significant feature in the diagnosis of papillary carcinoma. Ultrastructurally grooved nuclei showed a deep linear indentation of the nuclear membranes. Lobulated nuclei were characterized by multiple indentations that divided the nucleus into several lobules.

Ultrastructural morphometric analysis of papillary neoplasms: biological and diagnostic relevance

Ten papillary adenocarcinomas of thyroid origin (P-Thy), ten papillary adenocarcinomas of ovarian origin (P-Ov), and eight papillary neoplasms of non-thyroid/non-ovarian origin (P-Other) were morphometrically compared using 19 distinct quantitative nuclear and nucleolar parameters as a database for diagnosis. The selected cases consisted of 16 primary and 12 metastatic neoplasms. It was determined that the P-Thy group had a significantly smaller nucleolar area (NuA) and nucleolar perimeter (NuP), and smaller SDs of nuclear area (NA), NuA, and NuP compared with the P-Ov and P-Other groups (P less than .05). The P-Ov group had a significantly smaller SD of NA compared with the P-Other group (P less than .05). The P-Ov group exhibited the greatest variability among the papillary neoplasms. Linear regression analysis indicated that in the P-Thy group alone there was a significant correlation between mean nuclear form factor (4 pi A/P2) and mean NuA (r = -.82; P less than .01), and mean NP and mean NuA (r = +.77; P less than .01). Linear regression analysis also indicated that in the P-Ov group alone, there was a significant correlation between mean NA and mean NuA (r = +.75; P less than .02). Morphometric domains were established using statistically significant sets of variables that distinguished between the groups. The application of three-dimensional computerized cluster analysis techniques indicated that the P-Thy group consistently had the smallest morphometric domains. It was concluded that ultrastructural morphometric analysis of papillary neoplasms has diagnostic potential and reveals interesting biological relationships among distinct nuclear features in the different groups of neoplasms.

Hyalinizing trabecular adenoma of the thyroid. A report of three cases with immunohistochemical and ultrastructural studies

We have studied three examples of benign thyroid tumours which conform to the lesion recently described as hyalinizing trabecular adenoma. The prominent feature of this trabecular epithelial lesion is the extracellular deposition of an eosinophilic material that does not show the features of amyloid; the epithelial cells may be elongated, sometimes radially arranged around the eosinophilic material. All three tumours showed positive immunocytochemical staining for thyroglobulin, keratin, chromogranin and neuron-specific enolase. One tumour showed isolated cells with immunoreactivity for somatostatin, argyrophil cytoplasmic granularity with the Grimelius technique, and ultrastructurally demonstrable cytoplasmic electron-dense endocrine granules. The hyaline extracellular material in all three tumours showed strong immunoreactivity for both type IV collagen and laminin. Previous radiation may be important in the causation of this tumour, and it shows a frequent association with severe thyroiditis. We conclude that the main histological feature of this lesion, the hyaline material, is due to the overproduction of a basement membrane-like material by the neoplastic follicular cells. The presence in one tumour of evidence of endocrine differentiation may reflect the potential for follicular cells to show biphasic differentiation, a feature which may be more frequent than has been previously recognized. Several of the other features of this tumour--for example the frequent intranuclear cytoplasmic inclusions--may lead to diagnostic problems, and the entity deserves wider recognition.

Nuclear crease as a cytodiagnostic feature of papillary thyroid carcinoma in fine-needle aspiration biopsies

Nuclear crease or grooving was found to be a diagnostic feature of papillary thyroid carcinoma (PTC) in fine-needle aspiration (FNA) biopsies. The FNA biopsies of 37 cases of PTC, 50 cases of multinodular goiter, and 50 cases of follicular neoplasms (45 follicular adenomas and five follicular carcinomas) were examined. The diagnosis was histologically verified in all the cases. The nuclear crease was found to be present in 34 of 37 cases of PTC and in two of five cases of follicular carcinoma. There was no nuclear crease in any of the other cases examined. Thus, it is concluded that the nuclear crease is a fairly constant and characteristic feature of PTC in FNA biopsies and can be used as a valuable diagnostic criterion.

Oncocytic glomus tumour: a new variant

A new variant of glomus tumour characterized by oncocytic change is reported. The light and electron microscopy and immunohistological findings are described. This is the first reported case of an oncocytoma of non-epithelial origin.

Thyroglossal duct carcinomas: light and electron microscopic studies

Two cases of papillary carcinoma arising in thyroglossal duct cysts are reported. Electron microscopic studies were done on both cases and similar ultrastructural features were noted. When compared with a case of papillary adenocarcinoma arising in the thyroid gland proper, no difference was seen both at the light microscopic and ultrastructural levels.

Cytological findings in medullary carcinoma of the thyroid

In six cases of medullary carcinoma of the thyroid rather characteristic findings were seen in cytological specimens obtained by aspiration or imprint. The roundish-polygonal or spindle-shaped cells were predominantly disseminated, but occasionally arranged in small groups. The nuclei were frequently found in an excentric position; binuclear cells were sometimes encountered. In addition, five of the six cases showed intranuclear cytoplasmic inclusions which were also investigated by electron microscopy in specimens of two cases. Such inclusions in aspiration biopsies of the thyroid have so far been regarded, as characteristic for papillary carcinoma. In smears as well as in histological sections amyloid and calcitonin could be demonstrated by congo red staining and by immunocytochemistry, respectively. The cytomorphology of the tumor cells, their pattern of arrangement, and the peculiar nuclear inclusions make up a combination of findings that may justify the diagnosis of medullary carcinoma in aspiration biopsies. In smears the diagnosis can already be confirmed when (immuno-) cytochemical methods are applied to smear preparations.

Oncocytic hepatocellular tumour

A case of hepatocellular carcinoma in a non-cirrhotic liver of a 51-year-old female is described. The macroscopic appearance is of a well circumscribed tumour measuring 20 X 10 cm with a central fibrous scar. Histologically, the tumour is an unusual variant of epithelial liver cell tumour characterized by polygonal cells set in a fibrous stroma and showing oncocytic change. Electron microscopy confirms the oncocytic features. Oncocytic change in liver cell and other tumours is discussed.