Fine structure of human papillary thyroid carcinoma

Three-dimensional structural analysis of papillary thyroid carcinoma nuclei with serial block-face scanning electron microscopy (SBF-SEM)

Nuclear morphology of carcinoma cells is critical for the pathological diagnosis of papillary thyroid carcinoma (PTC). However, three-dimensional architecture of PTC nuclei is still elusive. In this study, we analyzed the three-dimensional ultrastructure of PTC nuclei using serial block-face scanning electron microscopy which takes advantage of the high-throughput acquisition of serial electron microscopic images and three-dimensional reconstruction of subcellular structures. En bloc-stained and resin-embedded specimens were prepared from surgically removed PTCs and normal thyroid tissues. We acquired two-dimensional images from serial block-face scanning electron microscopy and reconstructed three-dimensional nuclear structures. Quantitative comparisons showed that the nuclei of carcinoma cells were larger and more complex than those of normal follicular cells. The three-dimensional reconstruction of carcinoma nuclei divided intranuclear cytoplasmic inclusions into "open intranuclear cytoplasmic inclusions" connecting to cytoplasm outside the nucleus and "closed intranuclear cytoplasmic inclusions" without that connection. Cytoplasm with abundant organelles was observed in open inclusions, but closed inclusions contained fewer organelles with or without degeneration. Granules with a dense core were only observed in closed inclusions. Our observations suggested that open inclusions originate from nuclear invaginations, and disconnection from cytoplasm leads to closed inclusions.

Quantitative and qualitative differences in protein expression between papillary thyroid carcinoma and normal thyroid tissue

In order to better understand basic mechanisms of tumor development and identify potential new biomarkers, we have performed difference gel electrophoresis (DIGE) and peptide mass fingerprinting on pooled protein extracts from patients with papillary thyroid carcinoma (PTC) compared with matched normal thyroid tissue. Image analysis of DIGE gels comparing PTC and matched normal thyroid tissue protein indicated that 25% of the protein spots were differentially expressed at a 2.5-fold cutoff and 35% at two-fold. Comparison between two different pools of protein from normal thyroid tissues revealed differential protein expression of only 4% at 2.5-fold and 6% at two-fold cutoff. One hundred ninety-two protein spots were identified by MALDI-TOFMS, representing 90 distinct proteins. Excluding albumin, globins and thyroglobulin, imaging software determined 31 proteins to be differentially expressed at the two-fold (or greater) level. Individual gel comparisons (PTC vs. matched normal) from five patients established that 15/31 (48%) of these proteins exhibited statistically significant differential expression. Previously identified molecular markers in this group of proteins include cathepsin B, cytokeratin 19, and galectin-3. Novel differentially expressed proteins include S100A6, moesin, HSP70 (BiP), peroxiredoxin 2, protein phosphatase 2, selenium binding protein 1, vitamin D binding protein, and proteins involved in mitochondrial function. The use of two-dimensional gel electrophoresis (2DGE) revealed a significantly altered protein mass and/or pI in 10%-15% of proteins, suggesting alternatively spliced forms and other posttranslational modification of proteins revealed by this approach. We confirmed S100A6 as a potentially useful biomarker using immunohistochemical analysis (85% sensitivity and 69% specificity for distinguishing benign from malignant thyroid neoplasms). In summary, proteomic analysis of PTC using DIGE and mass spectrometry has confirmed several known biomarkers, uncovered novel potential biomarkers, and provided insights into global pathophysiologic changes in PTC. Many of the differences observed would not have been detected by genomic or other proteomic approaches.

The many faces and mimics of papillary thyroid carcinoma

This article provides an overview of the 15 histologic variants of papillary thyroid carcinoma listed by the 2004 World Health Organization (WHO) monograph on endocrine tumors. The histologic features, differential diagnosis, and clinical course of each variant are discussed in some detail. The follicular variants (conventional and macrofollicular) constitute a morphologic challenge because the majority of these tumors are encapsulated and, also, because, in many tumors, not all neoplastic cells show the nuclear features considered to be diagnostic of papillary carcinoma. As a result, most of these tumors are missed even by experienced pathologists. Moreover, hyperplastic thyroid lesions, follicular adenomas, and Hashimoto's thyroiditis may contain cells with clear nuclei resembling those of papillary carcinoma. Papillary carcinomas composed entirely of hyperchromatic cells have been overlooked. The WHO monograph defines papillary carcinoma with focal spindle and giant cell carcinoma components but its clinical behavior is unknown. Papillary carcinoma with an insular pattern that does not show the artifactual separation of the cell nests has been misinterpreted as the solid variant of papillary carcinoma. Papillary microcarcinomas include not only the conventional type and the follicular variants but also the tall cell and columnar cell variants.

Increased expression of genes encoding mitochondrial proteins in papillary thyroid carcinomas

To investigate differences in gene expression between normal thyroid tissue and papillary thyroid carcinomas, we performed differential display (DD) polymerase chain reaction (PCR) using total RNA from fresh-frozen surgically removed thyroid specimens. Four DD fragments that were overexpressed in tumor tissue were identified as parts of genes from the mitochondrial genome: nicotinamide adenine dinucleotide (NADH) dehydrogenase 5, adenosine triphosphate (ATP) synthase 6, cytochrome b, and cytochrome c oxidase I. The expression profiles of these genes were confirmed by hybridization using a DNA dot-blot array and radioactively labeled complex cDNA probes generated from tumor (30 biopsies) and nontumor (15 biopsies) total RNA. Cytochrome c oxidase III was also found to be overexpressed in papillary carcinomas, while the nuclear-encoded mitochondrial transcription factor A showed similar mRNA expression levels in tumor and nontumor tissue. Electron microscopy showed increased number and size of mitochondria in papillary carcinomas. Immunohistochemistry using a monoclonal antibody recognizing a nuclear-encoded mitochondrial protein showed positivity in all cases of papillary carcinoma (44 samples), while normal thyroid tissue (34 samples) was negative in all cases except 3, in which there was a weak, focal cytoplasmic staining. We conclude that papillary thyroid carcinomas show increased expression of mitochondrial mRNA and proteins, encoded by nuclear as well as mitochondrial genes.

Primary malignant melanoma of the uterine cervix: a case report

We report on a case of a malignant melanoma of the uterine cervix. Histological and immunohistological examinations of a postsurgical specimen revealed malignant melanoma. The junctional activities did not occur due to extensive superficial ulceration. Radical surgery was performed. The patient is doing well and free of symptoms at this time, 2 1/2 year later.

Macrofollicular variant of papillary thyroid carcinoma with minor insular component

BACKGROUND

The macrofollicular variant of papillary thyroid carcinoma that is the subject of this study has only recently been characterized. Information about its morphologic spectrum and biologic behavior is limited.

METHODS

The authors reviewed 29 examples, including 17 previously reported cases. The clinical and pathologic features of five patients who had the macrofollicular variant of papillary thyroid carcinoma with a minor insular component were analyzed in detail. The insular component in thyroid carcinomas has been associated with aggressive clinical behavior.

RESULTS

The ages of the 5 patients ranged from 31 to 70 years; the mean age was 40 years. Three patients presented with a palpable thyroid nodule and two with a large thyroid mass of long duration. The latter two tumors, which metastasized, were the largest (8 and 11 cm) and showed extrathyroidal and blood vessel invasion. All five tumors were composed predominantly of macrofollicles (>50%) and had a minor insular component that comprised less than 5% of the tumor mass. In most tumors, the macrofollicles were lined by cells with large, clear, grooved nuclei, and all five contained areas of conventional follicular variant of papillary thyroid carcinoma. In the two that metastasized, however, the lining of many macrofollicles consisted of cuboidal cells with small, hyperchromatic, follicular-type nuclei. Only the macrofollicular component was identified in the metastatic deposits in these two patients. All five patients were alive at last follow-up, two with metastases; but follow-up for this study is limited.

CONCLUSIONS

A minor insular component is an additional feature of the macrofollicular variant of papillary thyroid carcinoma that may aid in diagnosis and does not appear to have an adverse effect on the excellent prognosis of patients with these tumors.

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 macrofollicular variant of papillary thyroid carcinoma: a study of 17 cases

We report 17 cases of a distinctive variant of encapsulated papillary carcinoma that is likely to be confused with macrofollicular adenoma or nodular goiter. The tumors showed the unusual combination of macrofollicles and foci of the conventional follicular variant of papillary carcinoma. Macrofollicles occupied over 50% of the cross-sectional areas of the tumors. The macrofollicles were lined either by cells with large ground-glass nuclei, cells with large but less pale nuclei with stippled chromatin, or cuboidal cells with hyperchromatic nuclei. Solid foci were present in four tumors, and a focal insular growth pattern was noted in a fifth tumor. All patients were females ranging in age from 15 to 69 years (mean, 35.4 years). Despite the large size of the tumors (mean diameter, 4.8 cm), only two metastasized to cervical lymph nodes. One of these neoplasms showed extrathyroidal extension, while the other widely invaded the thyroid tissue through the tumor capsule. Multicentric foci of papillary carcinoma with a follicular nonsclerosing growth pattern were demonstrated in the contralateral lobe in two thyroid glands. All patients with follow-up were alive and symptom-free 2 months to 6 years following surgery.

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.

Mixed medullary-papillary carcinoma of the thyroid: a previously unrecognized variant of thyroid carcinoma

Two unusual medullary carcinomas of the thyroid gland and their metastases contained a population of cells (20% to 25%) with the characteristic clear nuclei of papillary carcinoma. The predominant component of the tumors exhibited the typical growth pattern and cytologic features of medullary carcinoma with abundant amyloid deposits. The cells with clear nuclei lined follicle-like or tubular structures. In both the primary and the metastatic lesions, immunoreactive thyroglobulin was demonstrated only in the cells with clear nuclei, while calcitonin, carcinoembryonic antigen, and neuron-specific enolase were present only in cells of the predominant medullary carcinomatous component. Moreover, intense and diffuse staining for cytokeratin was seen only in the cells with clear nuclei, but not in those of the major medullary carcinomatous component. These findings suggest the existence of a distinctive variant of mixed medullary-papillary carcinoma that can be recognized with routine stains.

Hyalinizing trabecular adenoma-like lesion in multinodular goitre

Hyalinizing trabecular adenoma, a recently characterized variant of thyroid adenoma, is often confused with a variety of lesions because of its unusual histological features (Carney, Ryan & Goellner 1987). We report a case of multinodular goitre in which there were several small nodules showing features of hyalinizing trabecular adenoma and peculiar nuclear rods.

The number of nucleoli in benign and malignant thyroid lesions: a useful diagnostic sign in cytological preparations

The slides of fine needle aspiration cytology specimens from 99 cases of cold thyroid nodules with known histology were reviewed and the number of nucleoli per nucleus counted and correlated with the different histopathological groups. Significant differences were observed between benign and malignant thyroid lesions in the number of nucleoli in the cytological material. Lower values were present in nodular goitres and follicular adenomas compared to carcinomas. In benign lesions the majority of nuclei contained one nucleolus and nuclei with two, three or more nucleoli were less frequent than in follicular, papillary, medullary and anaplastic carcinomas. Only one case of follicular adenoma had cells containing three or more nucleoli compared to more than half the cases of follicular carcinoma.

Nuclear chromatin texture to differentiate follicular and papillary carcinoma of the thyroid

This study presents the results of an automatic classification of six purely papillary, five purely follicular and five mixed papillary-follicular carcinomas of the thyroid. All cases were correctly classified with only two chromatin textural parameters obtained in the Olga's scan software package developed in our laboratory. Chromatin texture lines were generated by a unidirectional grey level gradient, obtained as a natural logarithmic function of the integrated optical density of each nucleus; this increased the difference between clear papillary and granular follicular nuclei. The accuracy of the method allowed a follicular carcinoma to be correctly classified as a mixed follicular-papillary. Finally a columnar-cell carcinoma of the thyroid was detected by means of its atypical DNA histogram.

Prognostic value of morphometry in papillary thyroid carcinoma

The value of morphometric analysis in addition to standard prognostic indicators was studied in 28 cases of papillary thyroid carcinoma. Standard features included age, sex, lymph node status, tumor size, and encapsulation. The mean follow-up was 47 months (maximum, 140 months). Recurrences were documented in six patients at a mean time of 34 months; five patients recurred with distal metastases and one patient recurred with local disease. Univariate analysis most closely associated tumor recurrence with nuclear anisotropism (the standard deviation of the estimated nuclear area [ENASD]) and tumor size. With forward stepwise incremental analysis, the value of tumor size was lost and only the ENASD and the cellularity mean index (CMI), defined as the percentage of tumor volume composed of tumor cells, significantly correlated with recurrence. Fifty-five percent of patients with an ENASD greater than 17 microns2 and a CMI greater than 40% developed recurrence as compared with 5% of patients with lesser values (P = .0001). Morphometric analysis may significantly contribute to the role of histopathology in the evaluation of papillary thyroid carcinoma and may also provide information regarding prognosis not obtained by standard methods.

Optically clear and vacuolated nuclei. Two useful signs for the transoperative diagnosis of papillary carcinoma of the thyroid

Ground glass nuclei and Orphan Annie Eye nuclei are currently accepted as the most useful signs for the diagnosis of papillary carcinoma of the thyroid. The nuclear appearance, however, is not used in transoperative studies because the general opinion is that they are only found in permanent sections. To compare the nuclear aspect of the permanent with frozen sections and imprints, a prospective double-blind study of 48 transoperative thyroid specimens was performed. The results show that the nuclei are similar when examined by the three techniques.

Nuclear grooves: a useful criterion in the cytopathologic diagnosis of papillary thyroid carcinoma

A recent report emphasized the usefulness of the grooved nucleus as a diagnostic criterion of papillary thyroid carcinoma (PTC) in histopathologic material. The present study was undertaken to evaluate whether grooved nuclei can serve as an additional diagnostic criterion for PTC in cytologic material obtained by fine-needle aspiration (FNA). Slides from 124 consecutive thyroid FNAs were reviewed. Specimens included 11 PTCs, one follicular carcinoma, six follicular adenomas, eight follicular neoplasms not otherwise specified, 10 cases of chronic thyroiditis, and 88 colloid nodules/adenomatous goiters. Among the PTC cases, grooved nuclei were found in all 11 (100%), intranuclear inclusions in nine (82%), papillary fragments in seven (64%), and psammoma bodies in two (18%). Nuclear grooves were also observed in two of the 113 non-PTC cases (1.8%), both of which were colloid nodules, one with extensive Hurthle-cell change. The grooved nuclei were best identified on Papanicolaou-stained material. They were inconspicuous and difficult to identify in air-dried Diff-Quik-stained material. It appears that the recognition of grooved nuclei among tumor cells is a valuable diagnostic feature of PTC in cytologic material stained with polychromatic Papanicolaou stain.

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.

Immunohistochemical localization of thyroglobulin (Tg), thyroxine (T4), and triiodothyronine (T3) in thyroid diseases

Thyroglobulin (Tg), thyroxine (T4), and triiodothyronine (T3) were detected by the immunoperoxidase method in 51 cases of the following thyroid diseases: euthyroid goiter, Basedow's disease, Hashimoto's thyroiditis, folliculo-papillary carcinoma, follicular carcinoma, anaplastic carcinoma, and medullary carcinoma. Tg, T3, and T4 are present in most of the examined disorders, excepting anaplastic and medullary carcinoma. The pattern of Tg, T3, and T4 distribution between the cases of a benign lesion is rather similar; Tg and T4 are localized both in the epithelium and the colloid; T3 is disposed especially in the follicular cells. The pattern of Tg, T3, and T4 distribution in differentiated carcinomas is more heterogeneous. In half of the cases, T3 distribution resembled that of Tg. In 2 cases, a predominance of T4 was noted. In the other specimens, T3 and T4 showed a weak or a negative immunostaining.

Dedifferentiation of a transplantable papillary thyroid carcinoma over a 15-year period

Fischer 344 rats on a prolonged low-iodine diet developed thyroid nodules which were transplanted subcutaneously into 33 thyroidectomized rats. One graft took and gave a papillary carcinoma. Serially transplanted syngeneically at 3- to 4-month intervals, it became autonomous in third generation hosts. With electron microscopy examination it was microfollicular in year 8 and anaplastic, with totally unpolarized epithelial cells, in year 15. Basement membrane present in year 1 was no longer visible in specimens of years 8 and 15. Tight and gap junctions still present in year 8 were absent in year 15, although a few desmosomes persisted. From years 8 to 15, free ribosomes and microfilaments became more frequent, whereas the number of mitochondria and the development of the Golgi complex declined.

The fine structure of papillary carcinoma of the thyroid

Eight human thyroid cancers (four papillary, and four lymph node metastases of papillary cancers) were studied at the ultrastructural level. The most characteristic anomalies affect the nucleus: "ground glass nuclei", highly indented nuclear membrane with formation of nuclear pseudoinclusions, nuclear bodies probably of nucleolar origin, fractionation of the periphery of the nucleus into multiple lobes joined by thin bridges of nuclear substance. Other abnormalities related to the mitochondria with decrease of size and number of cristae, the rough endoplasmic reticulum which was segregated in parallel saccules and the basal lamina was often reduplicated. The significance of these anomalies is discussed.

Electron microscopic investigations about the differentiation of thyroid carcinoma

36 thyroid carcinomas have been studied by means of electron microscopy. The specimens of 12 non-malignant thyroid lesions served as control. All the investigated tumours are composed of mixed populations of tumour cells differentiated in manifold variations. Differentiated carcinomas (follicular, papillary) often show misdifferentiations of the cytoplasm in light microscope, as well as in electron microscope. These misdifferentiations are the hyperplasia of a single cytoplasmatic organella or the hyperplasia of a system of organellas. The hyperplasia can be combined with a normal appearance of the respective organellas or with pathological changes of their morphology. Undifferentiated tumours often show structural remnants of folliculoid differentiation.

Neurosecretory granule-like structures in lymphomas

This report concerns the finding of round to ovoid electron dense, membrane bound structures 100 to 300 nm. in average diameter in four non-Hodgkin lymphoma cases studied ultrastructurally. In three of the cases the material for electron microscopy was obtained from lymph nodes. Two of the lymph nodes were replaced by nodular, poorly to moderately differentiated lymphocytic lymphoma, and the third was effaced by a diffuse histiocytic lymphoma. In the fourth case the specimen examined consisted of a spleen also replaced by nodular, poorly differentiate lymphocytic lymphoma. All cases appear to be primary abdominal lymphomas. The structures identified in the four lymphomas were similar in appearance to membrane bound neurosecretory granules when viewed by electron microscopy. It is proposed that the electron dense particles may represent peculiar lysosomes. Further cytochemical examination is needed to adequately characterize them. Although the presence of typical lysosomal granules in normal lymphocytes is a well known finding, we have not seen the type of granules described here i normal lymphocytes. Owing to the frequent use of electron microscopy examination to differentiate small cell undifferentiated (oat cell) carcinomas and, occasionally, other neuroendocrine neoplasms from lymphomas, the finding of these neurosecretory-like structures in lymphomas creates significant difficulty in the differential diagnosis and separation of these neoplasms by ultrastructural analysis.

Ultrastructural observations on the capillaries of human thyroid tumours

Ultrastructure of the capillaries of malignant and benign thyroid tumours has been examined. The material consisted of biopsies from six cases of thyroid papillary carcinoma, one case of follicular (foetal type) adenoma and six cases of nodular adenomatous goitre. In the group of nodular adenomatous goitre and in the follicular adenoma, the capillary wall was made up of fenestrated endothelium similar to that of capillaries of normal human thyroid. The fenestrae occupied a large area of the endothelial wall. Micro- and macropinocytotic vesicles were frequent in the endothelial cytoplasm. In the thyroid carcinomas the papillary structures always contained numerous capillaries with fenestrated endothelium. The microfollicular area and the solid tumoral areas of the papillary carcinoma showed occasional capillaries with fenestrated endothelium, but many capillaries were lined with continuous endothelium. The capillaries in all the specimens were surrounded externally by a continuous basement membrane which was frequently bilaminate or multilaminate. This study indicates that capillaries with fenestrated endothelium are characteristic of thyroid tumours which arise from follicular cells.

Anaplastic carcinoma of the thyroid gland. An ultrastructural study on four cases

Four cases of anaplastic carcinoma of the thyroid, composed of one small cell carcinoma and three giant cell carcinomas, were studied with electron microscope. In the case of small cell carcinoma, fine cytoplasmic interdigitations and junctional complex between apposing cytoplasmic membranes of neighbouring tumor cells and a few microlumina within tumor cell clusters surrounded by well-defined basal lamina were seen. In the cases of giant cell carcinoma, occasional cytoplasmic interdigitations as well as desmosomal structures were detected even in tumor cells markedly pleomorphic and anaplastic. Abundant cytoplasmic organelles including profiles of Golgi apparatus, rough endoplasmic reticulum and a few mitochondria were seen in the cytoplasm of tumor cell of all four cases. Of interest to note was that all giant cell carcinomas demonstrated evidences of fairly well differentiated tumor within anaplastic carcinoma, indicating probable pre-existing either benign or malignant epithelial neoplasm more differentiated, with its subsequent anaplastic transformation. Findings in the present study support an assumption that these anaplastic tumors are derived from the follicular epithelium of the thyroid gland. In addition, it can be said that tumor cells of the small cell carcinoma provide evidences suggesting functional differentiation of carcinoma cells to a certain extent, yet unable to produce thyroglobulin.

Triiodothyronine-secreting (toxic) adenoma of the thyroid gland: light and electron microscopic characteristics

A patient with thyrotoxicosis due to a triiodothyronine (T3)-secreting autonomous adenoma is described. The histmorphology of the neoplasms was similar to other neoplasms previously reported. Ultrastructural features of the adenoma are compatible with a very actively secreting follicular cell and are best compared with the ultrastructure of a diffuse toxic goiter. Distinctive features that separate toxic adenomas from various thyroid carcinomas and normal thyroid parenchyma are discussed.

Configuration of surfaces of human cancer cells in effusions. A scanning electron microscopic study of microvilli

The surfaces of viable cells of metastatic human carcinomas of various histologic types and primary origin, suspended in pleural and ascitic fluids, were shown by scanning electron microscopy to be covered by microvilli of variable configuration and distribution. Microvilli of some cancer cells appeared biologically active since they were capable of forming extensions and anastomoses when settling on glass. The possible specificity and significance of microvilli in the light of the experimental data were discussed.

Ultrastructure of anaplastic (spindle and giant cell) carcinoma of the thyroid

Three anaplastic (spindle and giant cell) carcinomas of the thyroid were studied by light and electron microscopy; two of the tumors also included foci of recognizable follicular carcinoma. The follicular carcinoma cells desplayed prominent mitochondria and rough endoplasmic reticulum, and showed evidence of secretory activity. Desmosomes and complex cellular interdigitations were evident. Basal laminae were present, with conspicuous reduplication in the well-differentiated foci. However, some epithelial clusters were surrounded by basal lamina, showing focal discontinuities through which epithelial cells protruded into the stroma. The pleomorphic spindle and giant cells showed cytoplasmic and nuclear characteristics similar to the better differentiated carcinomatous follicular elements, but showed rare desmosomes and no basal laminae. The basic ultrastructural similarity between follicular and anaplastic tumor cells confirms their common epithelial origin. However, while partially retaining their secretory capability, the anaplastic cells progressively lose their capacity to synthetize basal lamina and develop complex cellular attachments.

Malignant hemangioendothelioma of the heart with hematological disorders

An autposy case of a 30-year-old house wife with malignant hemangiothelioma of the heart was reported. This case was also accompanied by marked anemia, thrombocytopenia, leukoerythremoid reaction and hypofibrinogenemia. The spread of tumor was so wide that only the alimentary tract and the skin were free from metastases of the tumor. Many of the metastatic foci showed marked hemopoiesis intra tumori. A short discussion was made on the hematological abnormalities associated with vascular tumors.

Papillary clear cell carcinoma of the thyroid gland

A case of an unusual papillary clear cell carcinoma of the thyroid gland is described. The patient expired 17 days after operative biopsy and thyroxine suppression. Special stains were helpful in differentiating renal cortical carcinoma and parathyroid malignant disease from primary papillary clear cell carcinoma of the thyroid. Ultrastructural features of this tumor may relate to the effects of thyroid stimulating hormone as well as the malignant nature of the tumor.