Sergio Vidal

The spectrum of malignancy in craniopharyngioma.

Craniopharyngiomas are low-grade epithelial neoplasms occurring almost exclusively in the sellar/suprasellar region. Histologic malignancy is extremely rare; the literature consists mostly of isolated case reports. Herein, we report 3 patients with craniopharyngiomas exhibiting histologic malignancy, 2 of which received radiation therapy before its appearance. Hematoxylin and eosin-stained slides and selected immunohistochemical stains were reviewed in all cases. Microvessel density analysis was performed in case 2. The patients included 2 men and 1 woman, age 14, 31, and 58 years at presentation, respectively. All patients expired 3 months to 9 years after first resection and 3 to 9 months after identification of histologic malignancy. The latter developed after multiple recurrences and radiation therapy in 2 cases, but seemed to arise de novo in 1 case resembling odontogenic ghost cell carcinoma and lacking any definite low-grade craniopharyngioma precursor. The malignant component of the other 2 cases resembled squamous cell carcinoma and low-grade myoepithelial carcinoma, respectively. The MIB-1 labeling index was markedly increased in the malignant component in comparison with the low-grade precursor. Malignant transformation in craniopharyngiomas, although rare, does exist. It assumes varied histologic appearances, usually after multiple recurrences and radiation therapy, and has a near uniformly fatal outcome. De novo malignancy in odontogenic tumors of the sella is even more unusual, but also has an ominous prognosis.

Topoisomerase IIα Expression in Pituitary Adenomas and Carcinomas: Relationship to Tumor Behavior

DNA topoisomerase IIα (Topo IIα) is a molecular and immunohistochemical marker that indicates proliferation rate and is the target for several antineoplastic agents. The present immunohistochemical study of a large series of surgically removed pituitary tumors was designed to assess the prognostic significance of Topo IIα expression relative to patient age, gender, tumor type and size, invasiveness, metastasis, MIB-1–labeling index and angiogenesis. Changes of Topo IIα expression in the tumors treated with bromocriptine and octreotide, a long-acting somatostatin analogue were also investigated. Topo IIα immunopositivity was detected only in the nuclei of tumor cells. Gonadotroph adenomas, null cell adenomas, and ACTH-producing adenomas had the lowest Topo IIα indices, whereas primary pituitary carcinomas and silent type 3 adenomas presented the highest counts. The statistical study demonstrated no significant correlation between Topo IIα expression, patient gender, and vascularity. In contrast, significant negative correlation was found between Topo IIα expression and patient age. Topo IIα expression was significantly higher in invasive than noninvasive tumors. A tendency to have higher counts was also observed in microadenomas compared with in macroadenomas. Although Topo IIα and MIB-1 indices were similar in most tumor types, no significant correlation between Topo IIα and MIB-1–labeling indices (r = .16, P = .09) was found. Only non-functioning adenomas showed positive correlation (r = .41, P = .006) between both proliferation markers. Our results demonstrated a significant decrease in Topo IIα index in octreotide-treated, GH-producing adenomas, compared with untreated tumors, but no significant changes were observed in bromocriptine-treated, PRL-producing adenomas. The present study showed no significant advantage of Topo IIα over MIB-1 as a prognostic marker; however, Topo IIα may provide crucial information regarding selection of adenohypophyseal tumors responsive to antineoplastic therapy, such as invasive pituitary adenomas and pituitary carcinomas, which exhibit a high Topo IIα index.

Immunolocalization of vascular endothelial growth factor in the GH3 cell line

Abstract. The question of whether vascular endothelial growth factor (VEGF) is expressed in the GH3 cell line was investigated using immunocytochemistry, immunoelectron microscopy, and Western blotting. Using immunocytochemistry, VEGF was demonstrated in approximately 90% of the cells. Immunopositivity was localized mainly in the paranuclear Golgi region. In a small minority of cells, diffuse cytoplasmic immunostaining was also noted. By immunoelectron microscopy VEGF was evident in the secretory granules, cytoplasmic vesicles, rough endoplasmic reticulum, and the Golgi apparatus. Western blotting confirmed the results of the morphologic studies. It can be concluded that VEGF, which is know to induce angiogenesis and to increase vascular permeability, is produced in the prolactin- and growth hormone (GH)-secreting GH3 cell line. The functional role of VEGF in the GH3 cells is unknown. It is possible that this growth factor affects endocrine activity of GH3 cells by a paracrine mechanism.

Immunocytochemical Localization of Mast Cells in Lymphocytic Hypophysitis

We studied 15 transsphenoidally resected pituitary tissues diagnosed by histologic examination as chronic lymphocytic hypophysitis. Six autopsy-obtained pituitaries of patients who died of nonendocrine diseases also were studied. Tryptase immunohistochemical analysis, which specifically identifies mast cells, demonstrated numerous, randomly distributed multifunctional cells throughout the inflammatory reaction. Several mast cells were located in the vicinity of capillaries; several others were distributed far from the blood vessels. Occasional mast cells also were noted in the nonpathologic anterior and posterior pituitary lobes. Morphometric analysis confirmed that in lymphocytic hypophysitis, the number of mast cells per volume of tissue was significantly increased compared with that of nonpathologic anterior and posterior pituitary lobes. To elucidate the possible role of mast cells in chronic lymphocytic hypophysitis, microvessel densities were assessed quantitatively using immunohistochemical analysis for CD34, a sensitive marker of endothelial cells. The strong positive correlation between numeric density of mast cells and microvessel density per volume of pituitary tissue suggests that mast cell-derived products may influence capillary permeability and angiogenesis, thereby facilitating the access of inflammatory cells to adenohypophysial cells.

Myosin XVA expression in the pituitary and in other neuroendocrine tissues and tumors.

The myosin superfamily of molecular motor proteins includes conventional myosins and several classes of unconventional myosins. Recent studies have characterized the human and mouse unconventional myosin XVA, which has a role in the formation and/or maintenance of the unique actin-rich structures of inner ear sensory hair cells. Myosin XVA is also highly expressed in human anterior pituitary cells. In this study we examined the distribution of myosin XVA protein and mRNA in normal and neoplastic human pituitaries and other neuroendocrine cells and tumors. Myosin XVA was expressed in all types of normal anterior pituitary cells and pituitary tumors and in other neuroendocrine cells and tumors including those of the adrenal medulla, parathyroid, and pancreatic islets. Most nonneuroendocrine tissues examined including liver cells were negative for myosin XVA protein and mRNA, although the distal and proximal tubules of normal kidneys showed moderate immunoreactivity for myosin XVA. Ultrastructural immunohistochemistry localized myosin XVA in association with secretory granules of human anterior pituitary cells and human pituitary tumors. These data suggest that in neuroendocrine cells myosin XVA may have a role in secretory granule movement and/or secretion.

An easy method for the removal of Epon resin from semi-thin sections. Application of the avidin-biotin technique

SummaryA simple procedure is described for removing Epon resin from semi-thin 1 μm sections, which permits excellent postembedding immunohistochemical staining (avidin-biotin complex technique). The procedure was developed for the detection of growth hormone and prolactin in bovine adenohypophysis fixed with 2% paraformaldehyde and 0.5% glutaraldehyde in 0.1 m sodium cacodylate buffer pH 7.4–7.6. The results indicate that the removal of the epoxy embedding medium prior to the application of the immunohistochemical reagents was essential for the successful localization of the antigenic determinants of the two hormones. The immunocytochemical reactivity was obtained only after treating the sections with a solution of potassium hydroxide in a mixture of absolute methyl alcohol and propylene oxide (Maxwells solution). An enhanced immunoreactivity was obtained when this treatment was followed by an additional treatment with either 4% hydrogen peroxide or a saturated aqueous solution of sodium metaperiodate. Because of the easy preparation of the Epon removal solution and the good structural preservation without damage to the antigenic determinants, Maxwells solution is suggested as a good etching agent which can be used in immunohistochemical studies on semi-thin sections with excellent results.

Simultaneous localization of Pit-1 protein and gonadotropins on the same cell type in the anterior pituitary glands of the rat

Abstract Pit-1 is a prototypic member of the POU transcription factor family and plays a critical role in pituitary-specific action of growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) β-subunit genes. The purpose of the present study was to elucidate the changes in the expression of the Pit-1 product in the pituitary of pregnant rats employing an improved double-immunohistochemical method. The positive cells showed nuclear immunoreactivity and Pit-1 protein was frequently observed in the nuclei of many cells which were also immunopositive for GH, PRL, and βTSH. Unexpectedly, a significant number of pituitary cells containing both Pit-1 and gonadotropins were also observed. These cells were usually distributed near blood vessels that supply the pituitary. While a prominent increase in the percentage of Pit-1/PRL, Pit-1/β-luteinizing hormone and Pit-1/β-follicle-stimulating hormone immunoreactive cells was observed in pregnant rats, the percentage of Pit-1/GH immunoreactive cells was strongly decreased. In contrast, no significant differences in the percentage of Pit-1/βTSH doubly immunolabeled cells were noticed. Our findings strongly support the hypothesis that PRL could coexist in the Pit-1 immunopositive gonadotropes. Although Pit-1 protein was not detected in the nuclei of corticotropes, the existence of these cells in the rat pituitary cannot be excluded.

Immunohistochemical localization of amylin in human pancreas, thyroid, pituitary and their tumors

The aim of the present study was to investigate immunohistochemically expression of amylin, a 37 amino acid peptide, cosecreted with insulin by beta cells in pancreatic islets in 12 non-tumorous pancreatic tissues, 22 pancreatic islet tumors, 14 non-tumorous thyroids, 14 medullary carcinomas of the thyroid, 10 non-tumorous pituitaries and 50 pituitary adenomas including 10 amyloid-forming prolactin-cell adenomas using the streptavidin-biotin-peroxidase complex method. Amylin was expressed in non-tumorous pancreatic islets but not in non-tumorous thyroids and pituitaries. Since amylin plays an important role in amyloid formation in pancreatic islets, those tumor types were selected to study which may produce amyloid. Amylin was widely expressed in one insulin producing beta cell tumor. Few tumor cells were immunopositive in 8 islet-cell tumors and in 5 medullary thyroid carcinomas. Immunostaining was not found in pituitary adenomas, including those which produced amyloid. It can be concluded that amylin is not a satisfactory immunohistochemical marker to identify pancreatic islet tumors, medullary thyroid carcinomas and pituitary adenomas.

An immunohistochemical survey of nine cases of medullary carcinoma of thyroid including reactivity for Cox-1 and Cox-2 enzymes.

There has been much recent investigation of the cyclooxygenase (Cox) enzymes in tumor biology, but, to our knowledge, no study has yet been published describing Cox activity in medullary carcinoma of the thyroid (MTC). Nine cases of MTC from the past 10 yr were retrieved from our hospital archives. Slides cut from formalin-fixed paraffin-embedded tumor tissue from these cases were assessed for the activities of Cox-1 and Cox-2 enzymes by immunohistochemistry as well as by a battery of immunohistochemical stains for intermediate filaments, peptide hormone, and proliferation and promoter antigens. The staining reactions were semiquantitatively assessed and scored for comparison with each other as well as with each patient’s clinical presentation and course. Staining for Cox-1 and Cox-2 enzymes was present only in tumorous tissue, not in nontumorous thyroid tissue or C-cells. Cox-2 staining was not consistently increased over Cox-1 staining; however, Cox-2 staining bore statistically significant correlations with the expression of low molecular weight keratin, thyroid-transforming factor-1, topoisomerase, and MIB1. Hyperplastic C-cells from patients with diverse physiologic conditions and from three patients with C-cell hyperplasia accompanying medullary carcinoma or multiple endocrine neoplasia type IIa showed no reactivity for the Cox antibodies. It appears that Cox enzyme immunoreactivity is present only in the neoplastic C-cells of medullary carcinoma, but with variable expression. A practical application of the preceding finding might involve the use of Cox staining to distinguish invasive medullary carcinoma cells from hyperplastic C-cells.

Presence of mammosomatotropic (MS) cells in mink (Mustela vison) adenohypophysis

This study was undertaken to investigate the presence of mammosomatotrophs (MS) cells in the suckling mink. Using the double immunolabeling procedure, with colloidal gold as label, we demonstrated the existence of MS cells in these animals. Only one type of MS cells has been observed. These cells showed a great morphological similarity to classic prolactin (PRL) cells. MS cells of suckling mink were pleomorphic in appearance with many processes, their nuclei were irregular and their Golgi apparatus and endoplasmic reticulum were poorly developed. Their secretory granules were small (about 144 nm in mean diameter) and round. Two types of secretory granules have been found: monohormonal including PRL (the more frequent) and growth hormone (GH) (very scanty) granules, and bihormonal granules distributed between the former. We propose that MS cells of the mink, like other species, could represent an intermediate cell type in the transformation process of GH cells into PRL cells.