Lloyd, Ricardo V.

Abstract Context Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced as a new entity replacing the diagnosis of noninvasive encapsulated follicular variant of papillary thyroid carcinoma (PTC). Significant variability in the incidence of NIFTP diagnosed in different world regions has been reported. Objective To investigate the rate of adoption of NIFTP, change in practice patterns, and uniformity in applying diagnostic criteria among pathologists practicing in different regions. Methods Two surveys distributed to pathologists of the International Endocrine Pathology Discussion Group with multiple-choice questions on NIFTP adoption into pathology practice and whole slide images of 5 tumors to collect information on nuclear score and diagnosis. Forty-eight endocrine pathologists, including 24 from North America, 8 from Europe, and 16 from Asia/Oceania completed the first survey and 38 the second survey. Results A 94% adoption rate of NIFTP by the pathologists was found. Yet, the frequency of rendering NIFTP diagnosis was significantly higher in North America than in other regions (P = .009). While the highest concordance was found in diagnosing lesions with mildly or well-developed PTC-like nuclei, there was significant variability in nuclear scoring and diagnosing NIFTP for tumors with moderate nuclear changes (nuclear score 2) (case 2, P < .05). Pathologists practicing in North America and Europe showed a tendency for lower thresholds for PTC-like nuclei and NIFTP than those practicing in Asia/Oceania. Conclusion Despite a high adoption rate of NIFTP across geographic regions, NIFTP is diagnosed more often by pathologists in North America. Significant differences remain in diagnosing intermediate PTC-like nuclei and respectively NIFTP, with more conservative nuclear scoring in Asia/Oceania, which may explain the geographic differences in NIFTP incidence.

AbstractObjectiveTo profile clinically non‐aggressive and aggressive pituitary adenomas (PAs)/pituitary neuroendocrine tumours (PitNETs) and pituitary carcinomas for somatic mutations and epigenetic alterations of genes involved in cell proliferation/differentiation, microRNAs (miRNA)/long noncoding RNA (LncRNA)‐post‐transcriptional regulators and therapy targets.DesignRetrospective observational study.Patients and MeasurementsA total of 64 non‐aggressive and 41 aggressive PAs/PitNETs and 6 pituitary carcinomas treated by endoscopic surgery with ≥1‐year follow‐up were included. Somatic mutations of 17 genes and DNA methylation of 22 genes were assessed. Ten normal pituitaries were used as control.ResultsWe found at least one mutation in 17 tumours, including 6/64 non‐aggressive, 10/41 aggressive PAs/PitNETs, and 1/6 pituitary carcinoma. AIP (N = 6) was the most frequently mutated gene, followed by NOTCH (4), and TP53 (3). Hypermethylation of PARP15, LINC00599, ZAP70 was more common in aggressive than non‐aggressive PAs/PITNETs (p < .05). Lower levels of methylation of AIP, GNAS and PDCD1 were detected in aggressive PAs/PITNETs than non‐aggressive ones (p < .05). For X‐linked genes, males presented higher level of methylation of FLNA, UXT and MAGE family (MAGEA11, MAGEA1, MAGEC2) genes in aggressive vs. non‐aggressive PAs/PITNETs (p < .05).In pituitary carcinomas, methylation of autosomal genes PARP15, LINC00599, MIR193 and ZAP70 was higher than in PAs/PITNETs, while X‐linked genes methylation level was lower.ConclusionsSomatic mutations and methylation levels of genes involved in cell proliferation/differentiation, miRNA/LncRNA‐post‐transcriptional regulators and targets of antineoplastic therapies are different in non‐aggressive and in aggressive PAs/PitNETs. Methylation profile also varies according to gender. Combined genetic‐epigenetic analysis, in association with clinico‐radiological‐pathological data, may be of help in predicting PA/PitNET behaviour.

Pituitary tumor transforming gene (PTTG) was initially found to be overexpressed in GH4 rat pituitary adenomas (PA). PTTG overexpression has been correlated with patient survival, tumor grade, and/or invasiveness in several tumors including those of thyroid, breast, lung, and colon. Studies of PTTG as a prognostic indicator in PAs are limited and show conflicting results. We investigated PTTG immunostaining in 79 PAs of different subtypes (growth hormone (GH), 12; prolactin (PRL), 6, adrenocorticotropic hormone (ACTH), 11, gonadotroph, 21; null cell, 29) in relation to clinico‐pathological variables including patient age and sex, as well as tumor size, and invasiveness. The streptavidin‐biotin‐peroxidase method was used, with a monoclonal PTTG antibody (Abcam, Cambridge, UK). PTTG expression was found to be cytoplasmic in all PAs, with highest levels being present in GH adenomas and lowest in the PRL ones. No correlation was found with patient age, sex, tumor size or invasiveness. Thus, it appears that PTTG cannot serve as a prognostic marker in patients with PAs. PTTG has been implicated in several tumorigenic processes including angiogenesis, DNA damage repair and invasiveness. PTTG overexpression in PA warrants further research into its role in PA initiation and progression.

Abstract Context. —Pituitary adenomas are clinically diagnosed based on radiologic studies and/or secondary effects of hormone production. Definitive pathologic identification relies on immunohistochemical detection of a clonal population of hormone-producing cells. However, not all adenomas secrete hormones, so performing a battery of stains is inefficient. Reports have shown decreased type IV collagen in the stroma of other epithelial tumors. Objective. —To validate type IV collagen immunohistochemistry as a diagnostic method. Design. —We immunostained 27 adenomas and 19 normal pituitaries. The areas with the sparsest type IV collagen fibers were viewed at 3 magnifications (×10, ×20, and ×40 objectives), counting 1, 3, or 10 microscopic fields. A field was scored as “traversable” if a path existed from any point on the periphery of the field to a point on the approximately opposite periphery that did not cross any stained fibers. Results were compared with reticulin staining and to the existing diagnosis previously determined by histology, hormone immunostaining, and clinical correlation. Results. —Adenomas have less type IV collagen in their basement membranes, leading to sparser, trabecular staining in neoplasms versus a more rigid meshwork pattern in normal glands. One might envision the stained fibers as maze walls—one can traverse medium-powered fields in an adenoma, but one hits dead ends and gets trapped in those of a normal gland. Finding a single representative ×10 field to be traversable was 97.5% sensitive and 96.5% specific for an adenoma. Reticulin staining yielded identical results. Conclusions. —Type IV collagen immunostaining is a simple and reliable method of diagnosing pituitary adenomas.

SNAP‐25, a synaptosome associated exocytosis protein of 25 kDa plays an important role in the secretory activity of several endocrine cells. In the present study, we investigated 15 PRL, 10 GH, 5 ACTH, 5 TSH, 15 FSH/LH/ alpha subunit producing, and 5 null cell adenomas. Surgically removed, formalin‐fixed and paraffin embedded human pituitary tumors were used. Sections were immunostained by the streptavidin‐biotin‐peroxidase complex method. The results showed that 10 PRL producing adenomas were strongly immunoreactive for SNAP‐25. The immunopositive material was located mainly on the plasmalemma. The nuclei were immunonegative, the cytoplasm was mildly immunopositive in several cells. Treatment of patients with dopamine agonists before surgery decreased markedly SNAP‐25 immunopositivity in 5/10 cases. In GH producing adenomas SNAP‐25 was seen in 5 cases. Immunopositivity was mild‐ moderate, membrane bound and cytoplasmic. Somatostatin analogs caused no marked reduction in immunopositivity (5 cases). Other adenoma types were practically immunonegative. Among human pituitary adenomas only PRL producing tumors release their secretory granules via exocytosis as was demonstrated by electron microscopy. This observation is concordant with our results. In dopamine agonist treated patients, decreased SNAP‐25 expression in PRL producing adenoma cells is consistent with reduction of blood PRL levels.

PURPOSE: The p27kip1 protein (p27) is a cyclin-dependent kinase inhibitor that has been shown to be an independent prognostic factor in a variety of human neoplasms. Low expression of p27 tends to occur in more aggressive neoplasms. The role of p27 as an independent prognostic factor in the spectrum of myxoid and round-cell liposarcomas has not been examined. MATERIALS AND METHODS: Forty-seven cases of myxoid and round-cell liposarcomas were examined. Clinicopathologic features and immunohistochemical expression of p27 and Ki-67 antigen were studied in all cases. Survival analysis was performed using the log-rank test and the Cox multivariate regression model. RESULTS: The male:female ratio was 1.4:1, and the mean age at diagnosis was 45 years. The tumors were located in the lower extremities (94%) and retroperitoneum (6%). The median tumor size was 13.5 cm. The median follow-up was 6.3 years, and the overall 5- and 10-year survival rates were 76% and 67%, respectively. Low expression of p27 was identified in 34 cases (72%) and correlated with decreased metastasis-free (P = .026) and overall survival (P = .008). In a multivariate analysis, only round-cell differentiation and low expression of p27 independently predicted decreased metastasis-free and overall survival. CONCLUSION: p27 expression predicts the clinical behavior of myxoid and round-cell liposarcomas, even in neoplasms with few or no round-cell differentiation.

AbstractMice homozygous for the targeted disruption of the glycoprotein hormone α-subunit (αGsu) display hypertrophy and hyperplasia of the anterior pituitary thyrotropes. Thyrotrope hyperplasia results in tumors in aged αGsu−/− mice. These adenomatous pituitaries can grow independently as intrascapular transplants in hypothyroid mice, suggesting that they have progressed beyond simple hyperplasia. We used magnetic resonance imaging to follow the growth and regression of thyrotrope adenomatous hyperplasia in response to thyroid hormone treatment and discovered that the tumors retain thyroid hormone responsiveness. Somatostatin (SMST) and its diverse receptors have been implicated in cell proliferation and tumorigenesis. To test the involvement of SMST receptor 2 (SMSTR2) in pituitary tumor progression and thyroid hormone responsiveness in αGsu−/− mutants, we generated Smstr2−/−, αGsu−/− mice. Smstr2−/−, αGsu−/− mice develop hyperplasia of thyrotropes, similar to αGsu−/− mutants, demonstrating that SMSTR2 is dispensable for the development of pituitary adenomatous hyperplasia. Thyrotrope hyperplasia in Smstr2−/−, αGsu−/− mice regresses in response to T4 treatment, suggesting that SMSTR2 is not required in the T4 feedback loop regulating TSH secretion.

Leptin is a circulating hormone secreted by adipose and a few other tissues. The leptin receptor consists of a single transmembrane-spanning polypeptide that is present as a long physiologically important form as well as in several short isoforms. Recent studies have suggested that the anterior pituitary may have a role in the regulatory effects of leptin in animal models. To test this possibility in human pituitaries, we examined the expression of leptin and OB-R in normal and neoplastic pituitaries, and the possible functions of leptin in the pituitary were also analyzed. Leptin was present in 20–25% of anterior pituitary cells and was expressed in most normal anterior pituitary cells, including ACTH (70% of ACTH cells), GH (21%), FSH (33%), LH (29%), TSH (32%), and folliculo-stellate cells (64%), but was colocalized with very few PRL cells (3%), as detected by double labeling immunohistochemistry with two different antileptin antibodies. In addition, leptin expression was detected by RT-PCR in some pituitary tumors, including ACTH (three of four), GH (one of four), null cells (two of four), and gonadotroph (one of four) tumors as well as in normal pituitary. Immunohistochemical staining showed greater immunoreactivity for leptin in normal pituitaries compared to adenomas. Treatment of an immortalized cultured anterior pituitary cell line, HP75, with leptin stimulated pancreastatin secretion in vitro. Leptin also inhibited cell growth in the human HP75 and in the rat pituitary GH3 cell lines. Both long (OB-Rb) and common (OB-Ra) forms of the leptin receptor messenger ribonucleic acid and leptin receptor protein were expressed in normal and neoplastic anterior pituitary cells. These findings show for the first time that leptin is expressed by most human anterior pituitary cell types and that there is decreased leptin protein immunoreactivity in pituitary adenomas compared to that in normal pituitary tissues. We also show that OB-Rb is widely expressed by normal and neoplastic anterior pituitary cells, implicating an autocrine/paracrine loop in the production and regulation of leptin in the pituitary.

AbstractWe examined the specific cell types in normal human pituitaries that expressed PRL receptor (PRL-R) messenger ribonucleic acid (mRNA) by combined in situ hybridization and immunohistochemistry. The distribution of PRL-R mRNA in 28 pituitary adenomas was examined by in situ hybridization and reverse transcription-PCR in 12 cases of adenomas. In another set of experiments, 34 PRL adenomas from men, women, and bromocriptine-treated patients were analyzed for PRL-R by in situ hybridization.In the normal pituitary, PRL- and LH-producing cells had significantly more mean grain counts per cell and higher percentages of cells positive for PRL-R than GH and TSH cells. PRL-R mRNA was present in all groups of adenomas by in situ hybridization and reverse transcription-PCR. PRL adenomas had a significantly higher density of labeling compared to other adenoma types. Although there was no difference in the levels of PRL-R mRNA in PRL adenomas from men and premenopausal and postmenopausal women, patients treated with bromocriptine before pituitary surgery had significantly lower levels of PRL-R compared to all other groups. These results indicate that in the normal pituitary, PRL and LH cells have the highest level of PRL-R mRNA, whereas PRL adenomas have significantly higher levels of PRL-R mRNA than other types of adenomas, and bromocriptine treatment decreases the levels of PRL-R mRNA in PRL adenomas.