Prognostic value of p53, bcl-2, and c-erbB-2 protein expression in phaeochromocytomas

Value of Immunohistochemical Expression of Apelin, Succinate Dehydrogenase B, Chromogranin B, Human Epidermal Growth Factor Receptor-2, Contactin 4, and Succinyl-CoA Synthetase Subunit Beta in Differentiating Metastatic From Non-Metastatic Pheochromocytoma and Paraganglioma

OBJECTIVE

We aimed to retrospectively collect pathologically identified pheochromocytoma and paraganglioma (PPGL) tumor tissues from our center and investigate the expression of apelin and succinyl-CoA synthetase subunit beta (SUCLG2), human epidermal growth factor receptor-2 (HER2 or ERBB-2), contactin 4 (CNTN4), chromogranin B (CHGB), and succinate dehydrogenase B (SDHB) in metastatic and non-metastatic PPGLs, for exploring their roles in the diagnosis of metastatic PPGLs.

METHODS

A total of 369 patients with pathologically and surgically confirmed PPGLs at Xiangya Hospital, Central South University, between June 2010 and June 2020 were retrospectively included. Sixty patients-12 patients with metastatic PPGLs and 48 patients with non-metastatic PPGLs-were selected through propensity score matching (1:4) to reduce the effect of PPGL type, sex, and age. We observed and quantified the expression of apelin, SDHB, CHGB, ERBB-2, CNTN4, and SUCLG2 in paraffin-embedded samples using immunohistochemical staining.

RESULTS

No significant differences were observed between the metastatic group and non-metastatic group with respect to the expression of CNTN4 and SUCLG2. The expression of apelin, SDHB, CHGB, and ERBB-2 was significantly different between the two groups. The expression of apelin, SDHB, and CHGB was significantly lower in the metastatic group than that in the non-metastatic group (P < 0.001). ERBB-2 expression was significantly higher in the metastatic group than in the non-metastatic group (P = 0.042). Kaplan-Meier analysis revealed that patients with negative expression of apelin, SDHB, and CHGB showed significantly lower metastasis-free survival than those with positive expression. Multivariate Cox analysis revealed that SDHB and CHGB levels were independently associated with metastasis-free survival.

CONCLUSION

The expression levels of apelin, CHGB, SDHB, and ERBB-2 may be predictive biomarkers for the diagnosis of metastatic PPGLs. Patients with negative expression of apelin, CHGB, and SDHB should be subjected to frequent postoperative follow-up procedures.

Emerging molecular markers of metastatic pheochromocytomas and paragangliomas

Metastatic pheochromocytoma/paraganglioma (PPGL) represents a major clinical challenge due to limitations in accurate diagnostic tools and effective treatments. Currently, patients classified at high-risk by means of clinical, biochemical and genetic criteria, require a lifelong monitoring, while it remains difficult to determine the metastatic potential of PPGL only on the basis of histopathological features. Thus, tumor molecular markers that improve the risk stratification of these patients are needed. In the past few years, we have witnessed an unprecedented molecular characterization of PPGL, which led to the emergence of promising candidate biomarkers predictive of metastatic behavior. Here, we briefly discuss these breakthroughs and provide some insights for the prospective implementation of molecular markers of metastatic PPGL in the clinical setting in years to come.

Pheochromocytoma in Dogs Undergoing Adrenalectomy

Pheochromocytoma is frequent in dogs and carries a guarded prognosis. Current histological criteria may not predict malignant behavior in dogs, similar to humans. In humans, characterization of tumors has been refined using the pheochromocytoma of the adrenal gland scaled score (PASS) and by immunohistochemistry. The study aim was to investigate PASS and immunohistochemical markers used in humans in 24 dogs with pheochromocytoma that underwent adrenalectomy. Dogs with pheochromocytomas were reviewed and tumors collected. Histological sections were evaluated to apply the PASS and were single-labeled for chromogranin A, Ki-67, COX-2, p53, BCL-2, c-erbB-2, vascular endothelial growth factor, and S100. Survival, age, and vascular and capsular invasion were compared for PASS and immunohistochemical markers; results of PASS were also compared for each marker. Associations between markers were tested. PASS and immunohistochemical markers did not differ for survival, age, and vascular and capsular invasion. Tumors showing BCL-2 expression in >50% cells had lower PASS than those with lower expression (PASS: 7 ± 2 vs 9 ± 2; P = .011). Tumors positive for S100 had higher PASS than those that were negative (PASS: 10 ± 2 vs 7 ± 2; P = .001). Results of the different markers were not associated. In conclusion, in the context of canine pheochromocytoma, PASS and the selected immunohistochemical markers are not associated with survival, age, or vascular or capsular invasion. The higher PASS in S100-positive tumors may indicate that pheochromocytomas developing morphologic changes acquire S100 expression. The significance of lower PASS in tumors with elevated BCL-2 expression is uncertain. Overall, the use of PASS and the present immunohistochemical markers may not be useful in dogs with pheochromocytoma.

Neuroendocrine Differentiation in Breast Cancer: Clinicopathological Significance of Bcl-2 Positive Solid Papillary Carcinoma

Solid papillary carcinoma (SPC) is considered a rare malignant breast tumor. Maluf and Koerner first reported this disease entity as a special type of ductal carcinoma in situ with several characteristic histopathological features, including low-grade cellular atypia, intracellular or extracellular mucin deposition, and solid papillary growth pattern, as well as neuroendocrine differentiation. The present paper describes a case of SPC with bcl-2 expression, which is known as a marker for malignancy of neuroendocrine tumors. Interestingly, despite bcl-2 expression being a poor prognostic indicator of neuroendocrine tumors, the patient with this tumor has achieved long-term survival (approximately 6 years) at the time of writing this report. Because previous investigators reported that bcl-2 expression might play a role in the inhibition of the development of breast cancer, we suggest that bcl-2 expression might reflect a good prognosis in patients with SPC, rather than being a poor prognostic indicator, as it is in several types of neuroendocrine tumor. However, to confirm this hypothesis, further investigation is required.

ERBB-2 overexpression as a risk factor for malignant phaeochromocytomas and paraganglinomas

OBJECTIVE

There are currently no good histological or molecular markers to differentiate benign from malignant phaeochromocytomas and paraganglinomas (PPGLs). Our previous cross-sectional study observed that ERBB-2 overexpression was associated with malignant PPGLs. This study aimed to evaluate the predictive value of ERBB-2 overexpression for metastasis in PPGLs in a large population.

METHODS

A total of 262 patients diagnosed as PPGLs in our institution between 2002 and 2012 were included. We analysed ERBB-2 protein expression in the primary PPGL tumours by immunohistochemistry (IHC) and ERBB-2 amplification by fluorescence in situ hybridization (FISH). Direct Sanger sequencing was performed to examine ERBB-2 exon 20 mutations. The occurrence of malignant PPGLs was documented in the follow-up period. Kaplan-Meier analysis and Cox proportional hazard models were used to evaluate the association between ERBB-2 overexpression and metastasis of PPGLs.

RESULTS

Twenty-six (9·9%) patients had ERBB-2 overexpression in their primary PPGL tumours, which was significantly associated with ERBB-2 amplification (17/25, 68%). No ERBB-2 mutation was found. At a median follow-up of 4·5 years, a total of 23 malignant PPGLs were documented, including eight (30·8%) patients in the ERBB-2 overexpression group and 15 (6·4%) patients in the ERBB-2-negative group. The incidence rate of metastasis was 5·3 per 100 person-years vs 1·4 per 100 person-years in the ERBB-2 overexpression and ERBB-2-negative groups (P < 0·001), respectively. Kaplan-Meier analysis showed that ERBB-2 overexpression was associated with decreased metastasis-free survival (P = 0·001, log-rank test). After adjusting for primary tumour size and location, Cox regression analysis revealed that ERBB-2 overexpression was independently associated with risk of malignant PPGLs (HR = 2·78; 95% CI, 1·12-6·90; P = 0·028).

CONCLUSION

Patients harbouring tumours with ERBB-2 overexpression have a significantly higher risk of developing malignant PPGLs.

Loss of SDHB Elevates Catecholamine Synthesis and Secretion Depending on ROS Production and HIF Stabilization

Germline mutations in genes encoding succinate dehydrogenase subunits are associated with the development of familial pheochromocytomas and paragangliomas [hereditary paraganglioma/pheochromocytoma syndrome (HPPS)]. In particular, a mutation in succinate dehydrogenase subunit B (SDHB) is highly associated with abdominal paraganglioma and subsequent distant metastasis (malignant paraganglioma), indicating the importance of SDHB genetic testing. The discovery of HPPS suggests an association among genetic mitochondrial defects, tumor development, and catecholamine oversecretion. To investigate this association, we transfected pheochromocytoma cells (PC12) with SDHB-specific siRNA. SDHB silencing virtually abolished complex II activity, demonstrating the utility of this in vitro model for investigating the pseudo-hypoxic drive hypothesis. Lack of complex II activity resulting from RNA interference of SDHB increased tyrosine hydroxylase (TH; the rate-limiting enzyme in catecholamine biosynthesis) activity and catecholamine secretion. Reduced apoptosis was observed accompanied by Bcl-2 accumulation in PC12 cells, consistent with the phenotypes of paragangliomas with SDHB mutations. In addition, SDHB silencing increased reactive oxygen species (ROS) production and nuclear HIF1α stabilization under normoxic conditions. Furthermore, phenotypes induced by complex II activity knockdown were abolished by pretreatment with N-acetyl cysteine (an ROS scavenger) and by prior HIF1α knockdown, indicating an ROS- and HIF1α-dependent mechanism. Our results indicate that increased ROS may act as signal transduction messengers that induce HIF1α stabilization and may be necessary for the pseudo-hypoxic states observed in our experimental model. To our knowledge, this is the first study demonstrating that pseudo-hypoxic states resulting from SDHB knockdown are associated with increased TH activity and catecholamine oversecretion.

Overexpression of the insulin-like growth factor 1 receptor (IGF-1R) is associated with malignancy in familial pheochromocytomas and paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (pheo/pgl) are neuroendocrine tumours derived from chromaffin cells. Although mostly benign, up to 26% of pheo/pgl will undergo malignant transformation. Reliable histological signs to differentiate benign pheo/pgl from malignant tumours are currently lacking. Increased IGF-1R expression has been shown during progression to metastatic phenotypes of several types of cancer.

OBJECTIVE

To analyse the distribution and expression of the IGF-1R in pheo/pgl of different genetic origin and degree of malignancy.

MEASUREMENTS

We studied the expression of the IGF-1R protein by immunohistochemistry, in 40 primary tumours from patients with pheo/pgl from different genetic aetiology (11 of 29 metastatic/nonmetastatic diseases).

RESULTS

We found a strong association between increased expression of IGF-1R and malignant behaviour regardless of the age at diagnosis and the genetic aetiology. IGF-1R labelling was mostly weak in primary tumours from patients with nonmetastatic pheo/pgl. Conversely, intense IGF-1R labelling was predominant in cases of pheo/pgl with confirmed metastatic disease. The risk of metastases was 11·7 times higher if tumour IGF-1R labelling was intense independently of age at diagnosis. The probability of remaining free of metastases was higher in patients with pheo/pgl scored weak for IGF-1R at 60 months and more than twofold higher at 120 months of follow-up than in patients with intense IGF-1R labelling in their primary tumours.

CONCLUSIONS

Our results strongly suggest that IGF-1R is associated with malignancy in familial pheo/pgl and that IGF-1R expression in the primary tumour might be a useful tool to detect those patients harbouring pheo/pgl who have an increased risk of metastasis.

Gene expression profiles of phaeochromocytomas with ERBB2 overexpression reveal a new molecular mechanism tumourigenicity

OBJECTIVE

Phaeochromocytomas (PHEO) and functional paragangliomas (PGLs) are catecholamine-secreting neuroendocrine tumours. Although most PHEO/PGLs are benign, 10-35% present as (or develop into) malignant tumours with a poor prognosis. Overexpression of ERBB2 (v-erb-b2 erythroblastic leukaemia viral oncogene homologue 2) has been reported to be associated with malignant PHEO. We used gene expression profiling of PHEO/PGLs to gain a better understanding of the tumourigenic pathways associated with ERBB2.

METHODS

We used the Affymetrix Gene Chip U133 Plus 2·0 genome-wide gene expression cDNA microarray of 18 PHEO/PGLs (12 benign and six malignant, divided into two groups depending on ERBB2 expression levels) to analyse the gene expression patterns.

RESULTS

Unsupervised hierarchical cluster analysis of transcription profiles of 18 samples identified two dominant expression clusters corresponding to samples belonging to the ERBB2+ and ERBB2- groups. According to the gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases, the differentially expressed genes were classified into diverse functional categories and signalling pathways. In particular, the focal adhesion signalling pathway showed significant differences between the groups; specifically, the FAK-Src-MAPK pathway was prominently activated in the ERBB2+ group.

CONCLUSIONS

In summary, ERBB2+ PHEO/PGLs have a distinct expression pattern compared with the ERBB2- group. The focal adhesion signalling pathway may participate in ERBB2-induced tumourigenesis in PHEO/PGLs.

Malignant pheochromocytomas and paragangliomas: a diagnostic challenge

INTRODUCTION

Malignant pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare disorders arising from the adrenal gland, from the glomera along parasympathetic nerves or from paraganglia along the sympathetic trunk. According to the WHO classification, malignancy of PCCs and PGLs is defined by the presence of metastases at non-chromaffin sites distant from that of the primary tumor and not by local invasion. The overall prognosis of metastasized PCCs/PGLs is poor. Surgery offers currently the only change of cure. Preferably, the discrimination between malignant and benign PCCs/PGLs should be made preoperatively.

METHODS

This review summarizes our current knowledge on how benign and malignant tumors can be distinguished.

CONCLUSION

Due to the rarity of malignant PCCs/PGLs and the obvious difficulties in distinguishing benign and malignant PCCs/PGLs, any patient with a PCC/PGL should be treated in a specialized center where a multidisciplinary setting with specialized teams consisting of radiologists, endocrinologist, oncologists, pathologists and surgeons is available. This would also facilitate future studies to address the existing diagnostic and/or therapeutic obstacles.

Literature survey on epidemiology and pathology of gangliocytic paraganglioma

BACKGROUND

Although gangliocytic paraganglioma (GP) has generally been regarded as a neuroendocrine tumor, its origin remains unclear. We therefore aimed to investigate the details of this disease by carefully analyzing and extracting common features of the disease as presented in selected publications.

METHODS

We searched for English and Japanese cases of GP using the PubMed and IgakuChuoZasshi databases on August 2010. We then extracted and sampled raw data from the selected publications and performed appropriate statistical analyses. Additionally, we evaluated the expression of hormone receptors based on our previously reported case.

RESULTS

192 patients with GP were retrieved from the databases. Patient ages ranged from 15 y to 84 y (mean: 52.3 y). The gender ratio was 114:76 (male to female, 2 not reported). Maximum diameter of the tumors ranged from 5.5 mm to 100 mm (mean: 25.0 mm). The duodenum (90.1%, 173/192) was found to be the most common site of the disease. In 173 patients with duodenal GP, gastrointestinal bleeding (45.1%, 78/173) was found to be the most common symptom of the disease, followed by abdominal pain (42.8%, 74/173), and anemia (14.5%, 25/173). Rate of lymph node metastasis was 6.9% (12/173). Our statistical analysis indicated that significant differences were found for gender between GP within the submucosal layer and exceeding the submucosal layer. Furthermore, our immunohistochemical evaluation showed that both epithelioid and pancreatic islet cells showed positive reactivity for progesterone receptors.

CONCLUSIONS

Our literature survey revealed that there were many more cases of GP exceeding the submucosal layer than were expected. Meanwhile, our statistical analyses and immunohistochemical evaluation supported the following two hypotheses. First, vertical growth of GP might be affected by progesterone exposure. Second, the origin of GP might be pancreatic islet cells. However, it is strongly suspected that our data have been affected by publication bias and to confirm these hypotheses, further investigation is required.

Involvement of HER-2/neu and metastasis-related proteins in the development of ileal neuroendocrine tumors

HER-2/neu overexpression and/or gene amplification occurs in several human malignancies, frequently correlates with tumor aggressiveness, and provides the basis for treatment with trastuzumab. Among neuroendocrine neoplasms (NEN) of the gastroenteropancreatic (GEP) tract, ileal neuroendocrine tumors show peculiar features of malignancy with frequent metastases at the diagnosis. We investigated the overexpression and/or amplification of HER-2/neu and the involvement of the metastasis-related proteins c-Met, MTA-1, and VEGF in 24 primary ileal NEN by immunohistochemistry and fluorescence in situ hybridization (FISH). Data were compared with those of 43 GEP endocrine tumors of other sites. All primary ileal NEN showed an intense membranous and cytoplasmic immunostaining for HER-2/neu. According to the breast cancer scoring system, 17% of ileal carcinoids showed a score of 3+ and 71% with a score of 2+ with a significant difference respect the non-ileal GEP endocrine tumors (p < 0.0000). FISH analysis revealed chromosome 17 polysomy in 33% of 2+/3+ ileal tumors but not HER-2/neu gene amplification. The c-Met and MTA-1 but not VEGF were overexpressed in almost all ileal NEN, whereas VEGF presented more frequently a normal staining. The comparisons with the other GEP NEN demonstrated significant differences for all the three proteins (p < 0.0000, p < 0.0002, and p < 0.001, respectively). These findings suggest that in ileal NEN, HER-2/neu overexpression plays a role in the carcinogenetic process and by triggering the altered expression of c-Met and MTA-1, may activate the molecular pathway(s) promoting tumor progression and metastasis development. Ileal HER-2/neu overexpressing neuroendrocrine tumors may constitute potential candidates for target therapy with specific humanized monoclonal antibodies.

Duodenal gangliocytic paraganglioma showing lymph node metastasis: a rare case report

We describe a case of duodenal gangliocytic paraganglioma showing lymph node metastasis. A 61-year-old Japanese man underwent pylorus preserving pancreaticoduodenectomy to remove a tumor at the papilla of Vater. The section of the tumor extending from the mucosa to submucosa of the duodenum was sharply demarcated, solid, and white-yellowish. Neither necrosis nor hemorrhage was present. Histological examination confirmed the immunohistochemical identification of three components comprising epithelioid cells, spindle-shaped cells, and ganglion-like cells. Epithelioid cells showed positive reactivity for synaptophysin, somatostatin, and CD56. In contrast, spindle-shaped cells showed positive reactivity for S-100 protein, but not for synaptophysin, somatostatin or CD56. Furthermore, we found lymph node metastasis despite lack of bcl-2 and p53 expression. In addition to the rarity of the tumor, we are describing here the present case suggests the malignant potency of the tumor despite lack of acceptable prognostic indicators for neuroendocrine tumor.

Analysis of selected genes in neuroendocrine tumours: insulinomas and phaeochromocytomas

Insulinomas and phaeochromocytomas are neuroendocrine tumours that may be either sporadic or manifestation of a familial cancer syndromes and are both derived from the neural crest. In the present study, gene components of different signalling pathways were investigated in sporadic human insulinomas and phaeochromocytomas to identify the responsible candidates. Ret and k-ras were tested for activating point mutations, and NF1, p53, BRCA1, nm23-H1, SDHB and SDHD for loss of heterozygosity (LOH). Twenty-two sporadic insulinomas and 15 phaeochromocytomas were analysed by the polymerase chain reaction using restriction fragment length polymorphism or dinucleotide repeat polymorphism methods. The results of our analysis demonstrate that the most frequent changes were point mutations of k-ras: 23% of insulinomas and 62% of phaeochromocytomas harboured k-ras mutations. The analysis also showed two phaeochromocytomas with point mutations of the ret oncogene. Only one insulinoma showed LOH of NF1, and another showed LOH of p53. Allelic loss of BRCA1 was detected in two insulinomas, and of nm23-H1 in another insulinoma. Allelic losses of the SDHB gene were present in two phaeochromocytoma and one insulinoma cases and allelic losses of SDHD were present in one phaeochromocytoma case. The changes observed in phaeochromocytomas were more homogenous and confined to k-ras and ret oncogenes, whereas insulinomas showed more heterogenic situation. Our findings may contribute to a better understanding of the genetic profile of neuroendocrine tumours.

Prognostic indicators of malignancy in adrenal pheochromocytomas: clinical, histopathologic, and cell cycle/apoptosis gene expression analysis

BACKGROUND

Pheochromocytomas are malignant in approximately 10% of patients. The histologic differentiation between benign and malignant tumors is difficult, the latter diagnosed by the presence of metastatic disease or recurrence.

AIM

To determine if postoperative histologic evaluation using the previously proposed Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) and cell cycle/apoptosis markers can predict patients at risk for recurrence.

METHODS

Using the Memorial Sloan-Kettering Cancer Center adrenal database, we identified 48 patients with 51 resected pheochromocytomas (1987-2006). A senior endocrine pathologist, blinded to clinical outcome, reviewed the histopathologic characteristics of all cases using the PASS system. This pheochromocytoma scoring system is based on the presence of 12 different histologic parameters, including tumor necrosis, mitotic rate, tumor cell spindling, and the presence of large cell nests. In addition, we constructed a tissue microarray of all 5 malignant tumors and 41 of the benign tumors. By immunostaining of the tissue microarray, we assessed the expression of 7 different cell cycle/apoptosis-related genes (p53, Ki-67, Bcl-2, mdm-2, cyclin D1, p21, and p27).

RESULTS

Forty-three patients had a benign clinical course while 5 patients harbored a clinically malignant pheochromocytoma. Tumor necrosis (focal or confluent) was a particularly powerful indicator of malignancy present in 4 of 5 patients (80%) with malignant tumors, but only in 3 of 42 cases (7%) with benign neoplasms (P = .0009). The presence of a high mitotic rate (>3/10 high power fields) and tumor cell spindling significantly correlated with malignancy (P = .026 and .041, respectively). High cellularity was more often present in the malignant lesions (P = .050). There was a highly significant difference in PASS scores between benign and malignant cases (P = .0003). All malignant pheochromocytomas had a PASS score >/=6, well above the previously proposed >/=4 cutoff value. Two of the 4 patients testing positive for Ki-67 (>2% nuclear staining) had a clinically malignant course while only 3 (7%) of the 41 cases with lower Ki-67 positivity rate behaved in a malignant fashion (P = .055). Ki-67-positive tumor had a significantly higher chance of harboring tumor necrosis than Ki-67-negative neoplasms (P < .01). There was no difference in staining between benign and malignant pheochromocytomas using p53, Bcl-2, mdm-2, cyclin D1, p21, and p27.

CONCLUSIONS

(1) A PASS score of <4 predicted benign pheochromocytomas. (2) All malignant pheochromocytomas had a PASS score >/=6, which was significantly higher compared with the benign lesions. Patients with a PASS score >/=4 should be followed closely for recurrence. (3) p53, Bcl-2, mdm-2, cyclin D1, p21, and p27 appear to have no role in predicting the behavior of pheochromocytomas. Ki-67 may help identify those neoplasms at risk for recurrence by prompting the pathologist to look aggressively for adverse histologic features.

Frequent loss of 17p, but no p53 mutations or protein overexpression in benign and malignant pheochromocytomas

Genetic changes in the tumorigenesis of sporadic pheochromocytomas are poorly understood, and there are no good markers to discriminate benign from malignant pheochromocytomas. p53 is a tumor suppressor gene and aberrations in this gene are frequently found in many tumor types. The role of p53 in pheochromocytoma tumorigenesis is unclear, with some studies suggesting that p53 mutations can be used to discriminate benign from malignant pheochromocytomas while other studies do not find such an association. Because most of these investigations were hampered by small series of tumors and the use of varying methods, we have performed a comprehensive analysis of p53 aberrations in a large series of pheochromocytomas. Comparative genomic hybridization analysis of 31 benign and 20 malignant tumors showed loss of the p53 locus at chromosome 17p13.1 in 23/51 (45%) cases, and most of these results were confirmed by fluorescence in situ hybridization. Forty-three tumors, including the malignant tumors and the tumors with loss of the p53 locus, were analyzed for p53 mutations in exons 5-8, but none were found. Furthermore, p53 immunohistochemistry on 35 cases revealed strong nuclear p53 expression in only two pheochromocytoma metastases, all other tumors being negative. We conclude that, although there is frequent loss of the p53 locus on 17p, the p53 gene does not appear to play a major role in pheochromocytoma tumorigenesis.

Expression of activin and inhibin subunits, receptors and binding proteins in human pheochromocytomas: a study based on mRNA analysis and immunohistochemistry

OBJECTIVE

Pheochromocytomas are uncommon tumours arising from chromaffin cells of the adrenal medulla and related paraganglia. So far, one of the few reported markers to discriminate malignant from benign tumours is the betaB-subunit of inhibin and activin, members of the transforming growth factor (TGF)-beta superfamily of growth and differentiation factors.

DESIGN

We investigated the expression of the mRNAs coding for activin and inhibin subunits, their receptors and binding proteins by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and studied the presence of the inhibin betaB-subunit in human pheochromocytomas by immunohistochemistry.

PATIENTS

Samples from resected pheochromocytomas of patients operated between 1973 and 2003 were used for experiments.

RESULTS

The immunohistochemical investigations revealed that staining of the inhibin betaB-subunit was positive in 12 of 36 (33%) benign and 5 of 34 (15%) malignant pheochromocytomas (P > 0.05). Therefore, it was not possible to discriminate between benign and malignant tumours solely on the basis of inhibin betaB-subunit immunohistochemistry. Quantitative real-time RT-PCR in nine benign and four malignant tumours showed expression of inhibin alpha-, betaA- and betaB-subunits, the activin receptors Alk-4, ActRIIA, and ActRIIB, and the inhibin- and activin-binding proteins betaglycan and follistatin in all samples. No correlations were detected between individually coupled expression of mRNAs of these activin- and inhibin-related genes in the 13 pheochromocytomas. Only inhibin betaA-subunit expression was different in malignant compared to benign pheochromocytomas (P = 0.020).

CONCLUSIONS

No clear role for activin and inhibin was found in discriminating between benign and malignant pheochromocytomas.

Malignant pheochromocytoma: state of the field with future projections

The prevalence of malignant pheochromocytoma is about 10%, and is somewhat higher for paraganglioma. A problem for clinical follow-up is that patients with "benign" histopathologic findings may develop metastatic disease. At the first international symposium on pheochromocytoma in Bethesda (2005) experts from different disciplines and patients shared their experiences, and the present knowledge of this rare disease was updated. The discussion related to future strategies for better clinical/histopathologic diagnosis and understanding of different geno- and phenotypes. Curative surgery can only seldom be performed because of multiple metastases. The main therapeutic goal is therefore often tumor reduction and control of hypertension. To date the best adjunct to surgery is radionuclide therapy using 131I-MIBG, but the background information for optimal treatment is still incomplete. Certain patients may benefit from 131I-MIBG combined with radiotherapy via somatostatin receptors expressed by the tumor, or the combination with chemotherapy. The need for future multicenter studies was emphasized. In experimental models the work on enhanced expression of amine transporters critical for radiotherapy is continued. Ongoing microarray studies will reveal novel intracellular pathways of importance for proliferation/cell cycle control, which can be inhibited by pharmacologic tools.

A case of malignant pheochromocytoma with early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2

Defective apoptotic program due to the overexpression of the anti-apoptotic Bcl-2 protein of the outer mitochondrial membrane may be a cause of the poor response of malignant pheochromocytoma to 131I-MIBG therapy. We report a case of malignant pheochromocytoma which showed early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2 and which was refractory to 131I-MIBG therapy.

PTEN gene loss, but not mutation, in benign and malignant phaeochromocytomas

Mutations of the 'phosphatase and tensin homologue deleted on chromosome 10' (PTEN/MMAC1) gene have been associated with a variety of human cancers, including prostate cancer, glioblastoma, and melanoma. The gene is thought to be one of the most frequently mutated tumour suppressor genes and inactivation of PTEN is associated with disease progression and angiogenesis. High vascularization and resistance to chemo- and radio-therapy are two well-established features of phaeochromocytomas (PCCs). Furthermore, benign and malignant PCCs are found in several PTEN knockout mouse models. This study therefore evaluated whether inactivation of PTEN may be involved in the tumourigenesis of PCC in man and whether PTEN abnormalities may help to define the malignant potential of these tumours. Tumour and germline DNA was analysed from 31 patients with apparently sporadic PCC, including 14 clinically benign and 17 malignant tumours, for loss of the PTEN gene locus, mutations in the PTEN gene, and for PTEN protein expression by immunohistochemistry. Loss of heterozygosity (LOH) analysis showed loss of PTEN in four malignant tumours (40%) and in one benign tumour (14%). However, no mutations of PTEN were observed. Immunohistochemistry showed no correlation with clinical behaviour and/or LOH status. The results indicate that inactivation of the PTEN/MMAC1 gene may play a minor role in the development of malignant phaeochromocytomas.

New developments in the detection of the clinical behavior of pheochromocytomas and paragangliomas

Pheochromocytomas (PCC) are catecholamine-producing tumors that are, by definition, located in the adrenal medulla. Extra-adrenal catecholamine-producing tumors are called paragangliomas (PGL), which should be distinguished from head and neck paragangliomas, which are of parasympathetic origin. As is true for many (neuro)endocrine tumors, but unlike most other epithelial tumors, histopathological analysis does not allow a distinction to be made between PCC and PGL that will follow a benign course and those that have metastasized or will do so, a condition associated with poor prognosis. Therefore, many studies have been undertaken in the past decade, with the aim of providing a marker or a set of markers that allows clinical behavior in PCC and PGL to be predicted. Despite promising results in some areas, such as histopathological scoring systems, the use of the MIB-1 labeling index, and the analysis of telomerase activity, no single test or combination of tests has thus far yielded sufficiently high sensitivity and specificity to result in widespread acceptance in every day clinical practice. The relative rarity of PCC and PGL combined with a frequency of malignancy from as low as 2% up to 25% has hampered the power of past research and can only be overcome by multicenter collaborative efforts. In this article, recent attempts at marker detection, such as those mentioned above, as well as emerging knowledge on the molecular abnormalities in benign and malignant PCC and PGL will be presented.

An investigation into the role of Bcl-2 in neuroendocrine differentiation

INTRODUCTION

In addition to its role in apoptosis suppression, Bcl-2 has been reported to be co-expressed with neuroendocrine markers in several tissues, leading to speculation that this oncoprotein may promote neuroendocrine differentiation.

AIM

This study investigated whether Bcl-2 modulated neuroendocrine biopeptide expression.

METHODS

Levels of chromogranin A, neurone specific enolase, protein gene peptide 9.5, pancreatic polypeptide, and the chromogranin-derived peptides, intervening peptide and vasostatin-1 were examined by immunocytochemistry in rat phaeochromocytoma (PC12) cell lines genetically engineered to over-express Bcl-2 and their mock-transfected controls. Intensity of fluorescence was graded using a semi-quantitative scale from (-) indicating negative expression to (+++) indicating intense positivity.

RESULTS

Mann-Whitney U analysis indicated that no significant differences in expression existed between control and Bcl2 over-expressing cell lines for any of the six peptides examined.

CONCLUSIONS

The results of this study do not support the hypothesis that Bcl-2 promotes the acquisition of a neuroendocrine phenotype.

CGH and CD 44/MIB-1 immunohistochemistry are helpful to distinguish metastasized from nonmetastasized sporadic pheochromocytomas

The natural course of pheochromocytomas (PCC) cannot be predicted for certain on the basis of primary histology, their malignant character can only be confirmed by the occurrence of metastases during follow-up. Based on the recently proposed PASS score for evaluation we examined 37 adrenal (36 sporadic and one familial) and six sporadic extra-adrenal paragangliomas (all designated as pheochromocytomas) with a 'malignant histology' to find additional predictive factors. Drawing upon the follow-up (18 months to 12 years, mean 5.8 years) metastasized (n=20) and nonmetastasized (n=23) courses could be distinguished. Metastasized PCC revealed significantly (P=0.03) more copy number changes on comparative genomic hybridization (CGH) (mean 8.3) than nonmetastasized tumors (mean: 4.3). The most frequent chromosomal alterations were losses on 1p (75.6%) and 3q (44%). Both were detected with identical frequency in metastasized and nonmetastasized PCC. A gain on 17q (P=0.025) was significantly predominant in malignant courses and suggests similarities in the genetic origin and progression of PCC and neuroblastomas. The proliferative activity (MIB-1 score) of metastasized PCC (n=20) was found to be significantly higher in metastasized tumors (mean 12.8% vs mean 3.5%). In contrast, the semiquantitatively scored membrane-bound staining of CD 44-S was stronger in tumors without metastases (mean 2.1 vs mean: 0.25) during the follow-up period (P<0.01). Although the results correspond to the established weight differences the tumor weight does not appear to be an independent prognostic factor. Our study suggests that CD 44-S and MIB-1 immunostaining as well as the CGH results might complement the PASS score in predicting a metastasized course of PCC. Regardless of tumor weight, tumors with a 'malignant histology' are highly prone to metastasize when more than 5% of MIB1-positive nuclei are present or CD44-S immunostaining is negative, or both. PCC with 10 or more copy number changes on CGH must be referred to as malignant tumors.

The basic science of glomus jugulare tumors

Glomus tumors are a fascinating group of lesions. It is a challenge for neurosurgeons and otolaryngologists to resect them completely with minimal morbidity. Laboratory researchers have discovered extremely interesting genetic and molecular biology factors involved in the development and growth of glomus tumors. In this article the author reviews the genetics, protein mutations, angiogenesis and apoptosis associated with tumor formation, and the secretion of vasoactive substances is discussed as well. It is hoped that with further research less invasive measures may be developed to treat these tumors.

The clinically inapparent adrenal mass: update in diagnosis and management

Clinically inapparent adrenal masses are incidentally detected after imaging studies conducted for reasons other than the evaluation of the adrenal glands. They have frequently been referred to as adrenal incidentalomas. In preparation for a National Institutes of Health State-of-the-Science Conference on this topic, extensive literature research, including Medline, BIOSIS, and Embase between 1966 and July 2002, as well as references of published metaanalyses and selected review articles identified more than 5400 citations. Based on 699 articles that were retrieved for further examination, we provide a comprehensive update of the diagnostic and therapeutic approaches focusing on endocrine and radiological features as well as surgical options. In addition, we present recent developments in the discovery of tumor markers, endocrine testing for subclinical disease including autonomous glucocorticoid hypersecretion and silent pheochromocytoma, novel imaging techniques, and minimally invasive surgery. Based on the statements of the conference, the available literature, and ongoing studies, our aim is to provide practical recommendations for the management of this common entity and to highlight areas for future studies and research.

Expression of vascular endothelial growth factor (VEGF) and its cognate receptors in human pheochromocytomas

Pheochromocytomas are well-vascularized tumors, suggesting that a potent angiogenic factor may be involved in the mechanism of their formation. As vascular endothelial growth factor (VEGF) is a potent mitogen for vascular endothelial cells, here we have investigated the mRNA and protein expression of VEGF and the mRNA expression of its two receptors (Flt-1 and Flk-1/KDR) in pheochromocytomas tissue. An increase in VEGF mRNA (mainly isoforms VEGF(121) and VEGF(165)) and in VEGF protein expression were observed by semi-quantitative RT-PCR and Western blot, respectively, compared to normal adrenomedullary tissue. Flk-1/KDR, and Flt-1 levels of mRNA were also increased markedly in tumors and correlated with levels of VEGF mRNA. Therefore, we speculate that upregulation of VEGF expression and its receptors might be important in the pathogenesis of pheochromocytomas.

Laparoscopic adrenalectomy--indications and technique

Laparoscopic adrenalectomy has become the procedure of choice for the surgical management of most adrenal tumors, including functional and non-functional lesions. The role of laparoscopic adrenalectomy in the management of malignant adrenal tumors is controversial and most adrenocortical cancers are generally treated by open adrenalectomy. Laparoscopic adrenalectomy can be performed by both the anterior or lateral trans-abdominal approach and by the lateral or posterior retro-peritoneal approach, with each method being suitable for specific indications. Although there are no randomized trials comparing laparoscopic with open adrenalectomy, the laparoscopic approach is associated with shorter hospital stay, reduced pain and improved cosmesis. This review discusses the indications and contraindications, technique and outcomes for laparoscopic adrenalectomy.

Lack of histologically suspicious features, proliferative activity, and p53 expression suggests benign diagnosis in phaeochromocytomas

AIMS

The malignancy of phaeochromocytomas is difficult to predict. Traditionally, only a metastasized tumour is considered malignant. The aim of this study was to assess the histopathological and clinical features, as well as the proliferative activity, and to analyse p53 and p21 expression in 105 phaeochromocytomas.

METHODS AND RESULTS

All malignant phaeochromocytomas (n = 8) showed at least one of the histologically suspicious features, i.e. over five mitoses/10 high-power fields, necrosis, capsular or vascular invasion. Malignant tumours were larger, but the age and gender of the patients were not significantly different. All benign (n = 33) and most of the borderline (18/21) adrenal phaeochromocytomas had less than 6% Ki67+ tumour cells, while most malignant tumours (6/7) expressed Ki67 in >6% of the cells. p53+ immunohistochemistry was found in two malignant tumours, while p21 expression did not correlate with malignancy.

CONCLUSIONS

These data suggest that the lack of histologically suspicious features, low proliferative activity, smaller size, and negative p53 immunostaining point to a benign diagnosis in phaeochromocytomas.

Von Hippel-Lindau gene alterations in sporadic benign and malignant pheochromocytomas

The Von Hippel-Lindau (VHL) gene product has a wide spectrum of tissue-specific functions, and specific germline mutations are associated with clinical phenotypes in VHL disease. In particular, missense mutations are correlated with the susceptibility to pheochromocytomas. An association between VHL aberrations and prognosis has been suggested in renal clear cell carcinoma but has not been studied in pheochromocytomas. We studied the frequency and spectrum of VHL alterations in apparently sporadic pheochromocytomas in relation to the clinical behavior in 72 patients, including 48 patients with clinically benign and 24 patients with malignant pheochromocytomas. Single-strand conformation polymorphism (SSCP) analysis followed by DNA sequencing, loss of heterozygosity analysis of the VHL locus and immunohistochemistry for VHL protein expression were used to investigate somatic VHL gene alterations. In 2 patients, 1 with a malignant tumor, germline mutations were identified in the stop codon. Tumor-specific intragenic VHL mutations and accompanying loss of heterozygosity were identified in 2 (4.3%) of 47 sporadic benign pheochromocytomas compared to 4 (17.4%) of 23 malignant tumors (p = 0.064). Only one of these mutations has been previously described, in a renal clear cell carcinoma. Expression of the VHL protein was observed in all pheochromocytomas. No distinction in the nature of VHL alterations between benign and malignant pheochromocytomas and no correlation with histopathologic or clinical features was observed. We report novel VHL mutations in sporadic pheochromocytomas, which are slightly correlated with malignancy. VHL mutations may have some impact on the malignant transformation of pheochromocytomas.

Clinical and pathologic relevance of p53 index in canine osseous tumors

The clinicopathologic value of the immunohistochemical (IHC) expression of p53 protein was evaluated in 167 canine osseous tumors. p53 staining frequency and intensity in tumor cells was expressed as a p53 index. p53 index was significantly higher in osteosarcomas than in other sarcomas, chondrosarcoma, multilobular tumor of bone, and tumors initially misdiagnosed as osteosarcomas as well as in appendicular versus axial and in distal versus proximal osteosarcomas. A strong correlation is demonstrated between the p53 index and a range of clinicopathologic parameters in osteosarcoma, including the tumor site, histologic grade and score, mitotic index, degree of tumor necrosis, and pleomorphism. Chondroblastic osteosarcomas had significantly higher and telangiectatic osteosarcomas significantly lower p53 index than did osteosarcomas belonging to other histopathologic subtypes, a fact that tends to reinforce the perception of these osteosarcomas as distinct clinicopathologic entities. Entire males had higher p53 index than did neutered males. p53 index was higher in Rottweilers than in Great Danes and Terriers, confirming breed susceptibilities to osteosarcoma. p53 index showed no association with age, primary or secondary site status, or the presence of metastases or other tumor types. Biopsy samples had a higher p53 index than did postmortem samples, either because of differences in sample processing or the possibility that p53 overexpression is more evident at the earlier stages of osteosarcoma pathogenesis, presumably represented by the biopsy material. IHC examination for p53 and the derived index has the potential to be used as an additional diagnostic tool and prognostic indicator for osseous tumors.

Expression of HER-2/neu receptor protein in adrenal tumors

The HER-2/neu protein is overexpressed in many human carcinomas obtained from different tissues and may represent a useful target for therapy with the commercially available monoclonal antibody trastuzumab (herceptin). Novel therapeutic options are needed for metastasized adrenocortical cancer. Therefore, we studied expression of the HER-2/neu cell surface receptor protein using three different antibodies in 12 adrenal adenomas, 17 adrenocortical carcinomas and 5 pheochromocytomas. Normal adrenals (n = 5) served as controls. One adenoma showed very weak membranous immunostaining with the Dako antibody, two others showed a nonspecific cytoplasmic staining pattern. A nonspecific reaction in the cytoplasm was demonstrable in seven carcinomas with the Novocastra antibody. In all pheochromocytomas, a granular intracytoplasmic and, rarely, slightly membranous immunostaining with the Dako antibody was found. From our data we conclude that specific and significant membranous immunostaining indicating strong overexpression (grade 3) of HER-2/neu protein is not present in adrenocortical tumors. The granular cytoplasmic immunostaining of the medulla may be helpful for differentiation of adrenocortical tumors from pheochromocytomas.

KI-67 AND hTERT expression can aid in the distinction between malignant and benign pheochromocytoma and paraganglioma

The clinical and histopathological distinction between benign and malignant pheochromocytomas and paragangliomas is difficult, and reliable diagnostic markers are lacking. Here we have evaluated the prognostic value of human telomerase reverse transcriptase (hTERT) gene expression detected by reverse transcription PCR (RT-PCR); telomerase activity (TA) measured by TRAP (telomeric repeat amplification protocol) assay; immunohistochemical staining for Ki-67/MIB-1; and the mRNA expression of matrix metalloproteinase (MMP)-2 and EMMPRIN (extracellular matrix metalloproteinase inducer) analyzed by in situ hybridization in 32 primary pheochromocytomas or abdominal paragangliomas. hTERT was expressed in 7/11 malignant tumors (defined as presence of metastasis and/or extensive local invasion) as compared with in 2/21 benign tumors. All of the benign tumors showed <1% proliferative activity, as measured by Ki-67/MIB-1 staining. In all three patients with malignant tumors who developed metastases and/or invasive local recurrence during follow-up, the tumors were positive for either hTERT expression or Ki-67/MIB-1 immunoreactivity. TA was not a significant discriminator between benign and malignant tumors, and the value of EMMPRIN and MMP-2 as predictive markers was limited. In conclusion, the findings imply that the combined use of Ki-67/MIB-1 and hTERT, in addition to histopathology, provides a highly specific tool to identify benign pheochromocytoma and abdominal paraganglioma cases that are not at risk of developing recurrent or metastatic disease.

The molecular pathogenesis of hereditary and sporadic adrenocortical and adrenomedullary tumors

Modern imaging modalities lead to frequent detection of adrenal masses, most of them incidental findings. Although the majority of adrenocortical and adrenomedullary tumors are benign, there are no reliable clinical and laboratory markers to distinguish most of them from malignant neoplasms. The molecular mechanisms underlying the pathogenesis of these tumors have recently begun to be unraveled. A fruitful avenue for the elucidation of tumorigenesis has been the study of adrenal tumors that are manifestations of hereditary or postzygotic genetic syndromes, because one knows the "first hit", i.e. the primary gene defect. In contrast, in sporadic adrenal tumors the first hit, possibly a somatic mutation of a tumor-related gene, is unknown, and therefore the sequence of genetic alterations is difficult to establish. In this article we review in addition to our own work the literature on molecular aspects of adrenocortical and adrenomedullary tumorigenesis.

Differential heparanase-1 expression in malignant and benign pheochromocytomas

INTRODUCTION

Extracellular matrix (ECM) degradation is an essential step that allows tumor cells to penetrate a tissue barrier and become metastatic. Heparanase-1 (HPR) is an endoglycosidase that specifically degrades heparan sulfate proteoglycans, a chief component of the ECM. Previous studies have demonstrated HPR expression in various malignancies and that there is differential HPR expression between benign and malignant tumors. Currently, there is no technique that can reliably predict the malignant behavior of some pheochromocytomas. This study tests whether HPR is differentially expressed in malignant and benign pheochromocytomas.

METHODS

Paraffin-embedded specimens from 29 pheochromocytomas were evaluated. The tissues were collected from surgical specimens over a 10-year period from 26 patients (8 males, 18 females) with a mean age of 47 years (range 19-78 years, median 47 years). One female patient underwent 3 separate operations for malignant pheochromocytoma and thus provided 3 specimens. Another female patient had both the primary tumor and a liver metastasis processed, and therefore provided 2 specimens. Patient charts and pathology reports were reviewed to classify the pheochromocytomas as either benign or malignant. Based on clinical behavior and/or pathological evidence of metastasis or invasion into surrounding tissues, 10 specimens were malignant and 19 had benign behavior. As a control, normal adrenal tissue from 3 nephrectomy specimens was included in the study, as was tissue from 1 adrenocortical adenoma. All 33 specimens were tested for HPR gene expression by in situ hybridization (ISH) with an antisense RNA probe and immunohistochemistry (IHC) with an anti-HPR antibody. Statistical analysis was done using the chi(2) test of proportions to determine if HPR expression correlated with malignancy using ISH, IHC, or both tests together.

RESULTS

Using ISH, the percentage of HPR expression in the malignant pheochromocytomas was 50% while HPR expression in the benign tumors was 21% (P = 0.11). Using IHC, the percentage of HPR expression in the malignant pheochromocytomas was 80% while HPR expression in the benign tumors was 32% (P = 0.01). Considering both tests cumulatively, all 10 malignant pheochromocytomas stained positive for HPR by ISH and IHC, while only 37% of the benign tumors were positive for HPR expression (P = 0.001). The one adrenal adenoma and the 3 normal adrenal glands processed stained negative for HPR expression by both ISH and IHC.

CONCLUSIONS

HPR expression is higher in malignant pheochromocytomas than in benign pheochromocytomas or normal tissue. HPR may contribute to the invasive characteristics of malignant pheochromocytomas and might be used as a marker to distinguish malignant from benign pheochromocytomas. HPR expression might also be used as a prognostic tool in guiding long-term patient follow-up.

N-cadherin expression in adrenal tumors: upregulation in malignant pheochromocytoma and downregulation in adrenocortical carcinoma

Cell adhesion molecules (CAMs) are important regulators of tumor growth. The aim of the present study was to evaluate the expression pattern of CAMs in adrenal tumors regarding origin (cortex vs medulla) and biologic behavior (benign vs malignant). Eighty seven adrenal tumors were investigated by immunocytochemistry (ICC) using monoclonal antibodies against N-cadherin (NCAD), E-cadherin (ECAD), neural cell adhesion molecule (NCAM), and CD44. Western blotting was performed on 30 tumors using the same antibodies. Markers for proliferation (Ki-67) and catecholamine synthesis (tyrosine hydroxylase) were also analyzed in tumors by ICC. NCAD was expressed in 12/27 benign pheochromocytomas (BPCs) (12 familial cases), 8/8 malignant pheochromocytomas (MPCs), 28/30 adrenocortical adenomas, and 9/22 adrenocortical carcinomas. ECAD was expressed in 0/27 BPCs, 0/8 MPCs, 0/30 adrenocortical adenomas, and 2/22 adrenocortical carcinomas. NCAM was expressed in 26/27 BPCs, 7/8 MPCs, 21/30 adrenocortical adenomas, and 17/22 adrenocortical carcinomas. CD44 was expressed in 23/27 BPCs, 6/8 MPCs, 7/30 adrenocortical adenomas, and 4/22 adrenocortical carcinomas. Both cortical and medullary adrenal tumors expressed NCAD, NCAM, and CD44 but were devoid of ECAD. The expression of CD44 and NCAM did not correlate with the malignant potential of tumors. NCAD was upregulated in MPCs, but downregulated in adrenocortical carcinoma. Thus, NCAD appears to be involved in the development of both cortical and medullary adrenal tumors.

Losses of chromosomes 1p and 3q are early genetic events in the development of sporadic pheochromocytomas

Despite several loss of heterozygosity studies, a comprehensive genomic survey of pheochromocytomas is still lacking. To identify DNA copy number changes which might be important in tumor development and progression and which may have diagnostic utility, we evaluated genetic aberrations in 29 sporadic adrenal and extra-adrenal pheochromocytomas (19 clinically benign tumors and 10 malignant lesions). Comparative genomic hybridization was performed using directly fluorochrome-conjugated DNA extracted from frozen (16) and paraffin-embedded (13) tumor tissues. The most frequently observed changes were losses of chromosomes 1p11-p32 (86%), 3q (52%), 6q (34%), 3p, 17p (31% each), 11q (28%), and gains of chromosomes 9q (38%) and 17q (31%). No amplification was identified and no difference between adrenal and extra-adrenal tumors was detected. Progression to malignant tumors was strongly associated with deletions of chromosome 6q (60% versus 21% in clinically benign lesions, P = 0.0368) and 17p (50% versus 21%). Fluorescence in situ hybridization confirmed the comparative genomic hybridization data of chromosomes 1p, 3q, and 6q, and revealed aneuploidy in some tumors. Our results suggest that the development of pheochromocytomas is associated with specific genomic aberrations, such as losses of 1p, 3q, and 6q and gains of 9q and 17q. In particular, tumor suppressor genes on chromosomes 1p and 3q may be involved in early tumorigenesis, and deletions of chromosomes 6q and 17p in progression to malignancy.

Proliferative index in phaeochromocytomas: does it predict the occurrence of metastases?

Evaluation of the malignant potential of phaeochromocytomas in the absence of metastases presents a formidable challenge to both clinicians and pathologists. Until now, no widely accepted clinical, histological, immunohistochemical or molecular method has become available to discriminate malignant from benign phaeochromocytomas. In other endocrine tumours, estimation of proliferative activity by MIB-1 immunostaining has emerged as a promising approach for the determination of metastatic potential. In this study, the utility of MIB-1 immunostaining as a predictive marker for the occurrence of metastases in phaeochromocytomas was evaluated. In addition, the density of S100-positive sustentacular cells was studied, since their depletion has been identified as a negative predictive marker in smaller series. Furthermore, several clinicopathological parameters were evaluated. One hundred and ten patients operated on for a total of 99 benign and 37 malignant phaeochromocytomas were studied. All malignant tumours had documented metastases. The histopathological diagnosis of primary tumours and metastases was reviewed and graded for angioinvasion, capsular extension, and intra-tumoural necrosis. The proliferative index (percentage of MIB-1-positive cells) and the density of S100-positive cells were assessed. In addition, age at resection, associated familial tumour syndromes, tumour size, and tumour location were recorded. Univariate analysis revealed statistically significant correlations between malignancy and proliferative index (p<0.0005) and depletion of S100-positive sustentacular cells (p<0.0005). Fifty per cent of the malignant, but none of the benign phaeochromocytomas had a proliferative index greater than 2.5%. Higher age at resection (p=0. 03), sporadic occurrence (p<0.0005), extra-adrenal location (p<0. 0005), tumour size (p<0.0005), and necrosis (p=0.03) were also significantly associated with malignancy. Logistic regression showed that proliferative index (p=0.0072), size (p=0.0022), and extra-adrenal location (p=0.0012) of the primary tumour were independently predictive for malignancy. In conclusion, this study indicates that assessing the proliferative activity of phaeochromocytomas by MIB-1 immunohistochemistry can predict the occurrence of metastases. The predictive value of S100 immunostaining, tumour size, and extra-adrenal location of the tumour was also confirmed.