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

Thiazolidinediones inhibit the growth of PC12 cells both in vitro and in vivo

Thiazolidinediones (TZDs) have recently been proposed as a therapy for PPARgamma-expressing tumors. Pheochromocytoma (PHEO) is associated with high morbidity and mortality due to excess catecholamine production, and few effective drug therapies currently exist. We investigated the effects of TZDs on PHEO both in vitro and in vivo. PPARgamma protein was expressed in human adrenal PHEO tissues as well as in rat PHEO cells, PC12. TZDs, including rosiglitazone (RGZ) and pioglitazone (PGZ), inhibited proliferation of PC12 cells in a dose-dependent manner and increased casapse-3 expression of PC12 cells. TZDs also reduced expression of cyclin E and cyclin-dependent kinase2. RGZ inhibited nerve growth factor-induced neurite outgrowth and reduced expression of catecholamine-synthesizing enzymes. Finally, rat PHEO growth generated by subcutaneous injection of PC12 cells was slowed in an RGZ-treated mouse. These data suggest that TZDs may be a promising therapeutic approach for medical treatment for PHEO.

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.

Paraganglioma in pituitary fossa

Paragangliomas are neuroendocrine tumors of paraganglionic tissue which are extremely rare in the sellar area. We present a case of sellar paraganglioma with parasellar and suprasellar extension in a 70-year-old man who presented with headache. CT demonstrated sellar mass with suprasellar and right parasellar extension. The lesion was removed subtotally via a trans-sphenoidal approach. Histopathological diagnosis was paraganglioma. Differential diagnosis between paragangliomas and unusual types of pituitary adenomas, especially null-cell adenomas, is made by presence of cell nests (Zellballen) in paraganglioma, lack of immunopositivity for pituitary hormones, cytoplasmic immunopositivity for chromogranin A and neuron-specific enolase, and immunonegativity for cytokeratin 19, cytokeratin 20 and endomysial antibody. In the case of a mass in the sellar region, paraganglioma, although rare, should be included in the differential diagnosis.

Precursor Lesions of the Adrenal Gland

OBJECTIVE

To review the existing literature for evidence that adrenocortical and adrenomedullary tumours develop through a multistep process of carcinogenesis.

RESULTS

In the adrenal cortex hyperplasia and adenomas are frequently observed tumours or tumour-like conditions. In contrast, adrenocortical carcinomas are rare. Based on well-validated histopathological scoring systems, benign and malignant adrenocortical tumours can be separated, although a small subset of tumours remains hard to classify. Although extensive follow-up studies might argue against multistep carcinogenesis, analysis of chromosomal imbalances and gene expression profiling studies in these tumours are inconclusive and could give support for both multistep pathogenesis or de novo genesis of carcinomas. A major limit to most of these studies is the small sample size and the lack of extensive clinical (follow-up) data. In the adrenal medulla, pheochromocytomas (PCC) are the most frequent tumours in adults, with an incidence of 8 per million. They can be divided into benign and malignant PCC, but the distinction can only be made when metastases are present. Arbitrarily, lesions of less than 1 cm in diameter are called hyperplastic, but it should be expected that the majority of these are early lesions and if left in situ would grow to classify as PCC. In contrast to cortical tumours, the frequent 1p and 3q loss as an early event in tumourigenesis of benign PCC is verified in multiple studies. However, studies in malignant PCC yield divergent results, due to the small numbers analysed.

CONCLUSION

Taken together, there appears to be a relationship between cortical and medullary hyperplasia on the one hand and cortical adenomas and PCC on the other. However, whether there is a transition from benign to malignant tumours, both cortical and medullary, remains to be determined.

Telomerase and markers of cellular proliferation are associated with the progression of cervical intraepithelial neoplasia lesions

The expression of the catalytic subunit of telomerase protein (human telomerase reverse transcriptase [hTERT]), which is associated with telomerase activity, was evaluated as a potential marker of the high-grade premalignant cervical intraepithelial neoplasia (CIN 2/3) lesions. For comparison, cases of normal cervical squamous mucosa, low-grade CIN1 lesion, and cervical squamous cell carcinoma were included. The hTERT expression was also compared with Ki-67 and topoisomerase II-alpha (TPII-alpha) to determine the proliferative activity of the hTERT-positive dysplastic cells by a quantitative immunohistochemical staining method and was classified as follows: negative, 5% or less; moderate, 6% to 50%; or high, greater than 50% of the positive cells. The hTERT-positive cells were detected in a patchy pattern in the lower parabasal layers and in much of the basal layer in normal squamous mucosa. A similar frequency of Ki-67- or TPII-alpha-positive cells was observed, with the exception of the basal layer cells that were mostly negative. It is worthy to note that the recognizable intact basal layer cells in cases of CIN lesions were also consistently positive for the expression of hTERT, but rarely for Ki-67 or TPII-alpha. The expression of hTERT was detected in a less patchy pattern at a high or moderate percentage of the dysplastic epithelial cells each in 28.5% of cases of CIN1 lesions. A similar frequency, high and moderate percentage combined, of the TPII-alpha-positive dysplastic cell was also observed. In contrast, a high percentage of the hTERT-positive dysplastic cells were detected as diffuse basal or full-length thickness in 87.5% or 95% of cases of CIN2 or CIN3, respectively. A similar frequency of Ki-67 or TPII-alpha expression was observed in the dysplastic cells of CIN3 lesions. The pattern of hTERT-positive malignant cells in squamous cell carcinoma and dysplastic cells in the high-grade CIN lesions, to a greater extent, and dysplastic cells in the low-grade CIN lesion, to a lesser extent, was distinct from that of the normal cervical squamous mucosa. The results suggest that the progressive increase in the hTERT expression, together with the proliferative activity of the dysplastic epithelial cells of the high-grade CIN lesions, represents an early genetic abnormality in cervical pathogenesis.

Paraganglioma of the greater omentum: Case report and review of the literature

Background

Extra-adrenal, intra-abdominal paraganglioma constitutes a rare neoplasm and, moreover, its location in the greater omentum is extremely infrequent.

Case presentation

A 46-year-old woman with an unremarkable medical history presented with an asymptomatic greater omentum mass that was discovered incidentally during ultrasonographic evaluation due to menstrual disturbances. Clinical examination revealed a mobile, non-tender, well-circumscribed mass in the right upper and lower abdominal quadrant. Blood tests were normal. Contrast-enhanced abdominal computed tomography (CT) scan confirmed a huge (15 × 15 cm), well-demarcated, solid and cystic, heterogeneously enhanced mass between the right liver lobe and right kidney. Exploratory laparotomy revealed a large mass in the greater omentum. The tumor was completely excised along with the greater omentum. Histopathology offered the diagnosis of benign greater omentum paraganglioma. After an uneventful postoperative course, the patient was discharged on the 4^th postoperative day. She remains free of disease for 2 years as appears on repeated CT scans as well as magnetic resonance imaging (MRI) and scintigraphy performed with radiotracer-labeled metaiodobenzyl-guanidine (MIBG) scans.

Conclusion

This is the second reported case of greater omentum paraganglioma. Clinical and imaging data of patients with extra-adrenal, intra-abdominal paragangliomas are variable while many of them may be asymptomatic even when the lesion is quite large. Thorough histopathologic evaluation is imperative for diagnosis and radical excision is the treatment of choice. Since there are no definite microscopic criteria for the distinction between benign and malignant tumors, prolonged follow-up is necessary.

Clinical review: Current treatment of malignant pheochromocytoma

CONTEXT

Pheochromocytomas are rare tumors of predominantly adrenal origin that often produce and secrete catecholamines. Malignancy occurs in a variable percentage of cases depending on genetic background and tumor location. Definitive diagnosis relies on the detection of distant metastases. Treatments for malignant pheochromocytoma include surgical debulking, pharmacological control of hormone-mediated symptoms, targeted methods such as external irradiation, and systemic antineoplastic therapy. Different agents and protocols for this purpose are reviewed, and their therapeutic potential is discussed.

EVIDENCE ACQUISITION

Literature on antineoplastic therapies for malignant pheochromocytoma was identified by searching the PubMed database with restriction to articles published in English during the past 30 yr.

EVIDENCE SYNTHESIS

Because of the rarity of the condition, no randomized clinical trials concerning the treatment of malignant pheochromocytoma have been performed. The strategy established best is [131I]meta-iodobenzylguanidine (MIBG) therapy, which is well tolerated. Similar to cytotoxic chemotherapy with cyclophosphamide, vincristine, and dacarbazine, MIBG can induce remission for a limited period in a significant proportion of patients. Octreotide as a single agent seems to be largely ineffective.

CONCLUSIONS

MIBG radiotherapy and cyclophosphamide, vincristine, and dacarbazine chemotherapy are comparable with respect to response rate and toxicity. It is unclear whether combining both can improve the outcome. Future developments may include new multimodal concepts with focus on inhibition of angiogenetic factors and heat shock protein 90. Any present or new therapeutic approach must take into account the highly variable natural course of the disease.

Telomerase: is it the future diagnostic and prognostic tool in human cancer?

A number of methods exist to detect levels of telomerase activity and the presence of telomerase subunits in a variety of tissues. As telomerase activation seems to be an important step in tumorigenesis, accurate detection of the presence and activity of the enzyme and its subunits is vital. The original method of detecting telomerase activity was developed by Kim and coworkers in 1994, and was termed the telomeric repeat amplification protocol. This assay led to a staggering increase in the number of telomerase-associated publications in scientific journals (85 publications from 1974-1994, 5063 publications from 1994-2004). A number of methods have been described to detect telomeres and to measure their length, with the standard measurement of telomere length performed using a modification of the Southern blot protocol. RNA in situ hybridization can be performed to detect levels of the RNA component of telomerase, and standard in situ hybridization and immunohistochemistry can be applied to examine expression levels and localization of the catalytic subunit of the enzyme. Reverse transcriptase PCR has also been applied to assess expression levels of the telomerase components in various tissues. This review provides a synopsis of telomeres, telomerase, telomerase and cancer, and finally, methods for the detection of telomerase in cancer.

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.

Malignant Pheochromocytoma

Malignant pheochromocytoma is a rare disease with a high mortality. Surgical resection is the only effective treatment if extensive metastatic disease is not present. However, differentiating between benign and malignant pheochromocytoma is impossible in the absence of locoregional invasion or distant metastasis. This diagnostic dilemma has several drawbacks, including later detection and treatment of recurrence than if malignancy is determined at the original operation. With emerging molecular markers of malignant disease, optimal extent and approach for surgical treatment and appropriate extent of follow up could be established based on specific tumor behavior and the need for additional systemic therapy.

Differential expression of human telomerase catalytic subunit mRNA by in situ hybridization in pheochromocytomas

In pheochromocytomas, it is very difficult to predict malignant potential by conventional histology or immunohistochemical and molecular markers. We investigated the expression of human telomerase catalytic component (hTERT) mRNA, hTERT protein, Ki-67 antigen, and p27kip1 in pheochromocytomas (27 benign, 7 suspected malignant, and 7 malignant), and evaluated the possibility of expressions of these proteins, and hTERT mRNA serve as diagnostic markers for predicting the biological behavior of these tumors. All tumors showed the classical histology and typical immunohistochemical pattern. By in situ hybridization, hTERT mRNA was expressed in 5/7 malignant tumors (defined as the presence of metastasis and/or extensive local invasion) as compared with 3/27 benign tumors. We examined the hTERT by immunohistochemistry to confirm the mRNA. hTERT mRNA expression was correlated with hTERT protein expression. All benign tumors exhibited no immunopositivity or <1% of cells stained for Ki-67 antigen. Six out of seven malignant tumors have shown either hTERT mRNA expression or Ki-67 immunoreactivity. While no statistical difference in p27kip1 expressions was observed among benign, malignant, and suspected malignant tumors, there was a statistical difference between the normal adrenal medulla samples and tumors (p < 0.001). Thus, hTERT mRNA detection by in situ hybridization, hTERT expression, and Ki-67 antigen expression are all useful tools for differentiating malignant from benign pheochromocytomas.

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.

Composite paraganglioma-ganglioneuroma of the urinary bladder

Presented herein is the case of a 73-year-old man, complaining of dysuria, who had a composite paraganglioma-ganglioneuroma of the urinary bladder (CPGUB). At cystoscopy a submucosal tumor was found in the urinary bladder and resected after transurethral biopsy. The levels of serum catecholamine and 24 h urinary excretion of catecholamine and vanillylmandelic acid were elevated. Grossly, the resected tumor, measuring 4 x 3 x 2.5 cm, had a brownish cut surface with no necrosis and hemorrhage. Histologically, the tumor had alternating cellular and fibrous areas. The cellular areas consisted of polygonal cells, arranged in well-defined nests (Zellballen) and positive for Grimelius staining, with abundant amphophilic to acidophilic cytoplasm, occasionally containing eosinophilic hyaline globules and brown pigments. Although the nuclei of several polygonal cells were bizarre, mitoses and vascular invasion were not found. Fibrous areas consisted of spindle cells, resembling Schwann cell, admixed with ganglionic cells. To the authors' knowledge, only four cases of CPGUB have been reported in the English-language literature. Detailed reported cases and the present case showed no malignant features, such as extra-bladder infiltration and metastasis, and no recurrence in the short length of follow up. Accumulation of long-term follow-up cases may provide valuable prognostic information on this composite tumor.

Phaeochromocytoma: current concepts

The discovery of novel mutations in genes encoding succinate dehydrogenase subunits has revealed that familial phaeochromocytomas are much more common than previously thought. Genetic screening should be offered to patients with apparently sporadic phaeochromocytomas and their first-degree relatives. An increasing proportion of phaeochromocytomas present preclinically on genetic testing or as "incidentalomas" on abdominal imaging, rather than with classic symptoms and signs. Clinical suspicion should prompt measurement of plasma levels of free metanephrine or 24-hour urinary catecholamine and metanephrine levels, followed, if positive, by tumour localisation studies. With appropriate perioperative care, surgical management of phaeochromocytomas is safe and effective. Most tumours can be removed laparoscopically.

Pheochromocytoma and functional paraganglioma syndrome: no longer the 10% tumor

Pheochromocytomas and abdominal paragangliomas are catecholamine-producing tumors of the sympathetic nervous system, while head and neck paragangliomas are non-secreting tumors of parasympathetic origin. Recent developments in clinical and molecular research on these tumor forms have significantly clarified their genetic backgrounds and challenged the view of "pheochromocytoma as the 10% rule tumor." Firstly, a larger proportion of these tumors are today discovered in normotensive patients during imaging carried out for other reasons than suspicion of pheochromocytoma. Secondly, although the differential diagnosis between malignant and benign tumors remains a challenge, the risk of malignancy well exceeds the classical 10% in patients with extra-adrenal disease, and/or carriers of germ-line SDHB mutations. Finally, up to a third of patients carry a germ-line mutation in a gene predisposing to pheochromocytoma and/or paraganglioma. Identification of a constitutional mutation in RET, VHL, SDHD, or SDHB has implications for clinical screening and follow-up for both the patient and for relatives at risk who can be identified by screening for the same mutation. Genetic testing in apparently sporadic cases is therefore regarded as beneficial, especially in patients diagnosed before 50 years of age, and in patients with bilateral, multifocal, malignant and/or extra-adrenal disease.

Malignant retroperitoneal paraganglioma: case report and review of the literature

Paraganglioma is a rare neuroendocrine neoplasm observed in patients of all ages but it has not been characterized in children. The authors describe a retroperitoneal paraganglioma diagnosed by chance in an 11-year-old boy. Many aspects of retroperitoneal paraganglioma are still under investigation. The treatment of choice is radical resection. Surgery may be possible following chemotherapeutic debulking with cyclophosphamide, vincristine, and dacarbazine. 131I-MIBG radiotherapy has proved increasingly useful in reducing the pain associated with disseminated disease and also in facilitating surgical resection in cases that appear inoperable. Conventional radiotherapy is purely palliative and used to reduce the pain of bone metastases.

Malignancy in pheochromocytomas. Review article

A catecholamine-secreting tumor arising from the chromaffin cells of the sympathoadrenal system was first termed pheochromocytoma by Poll in 1905. The term refers to the dysky (pheo) color (chromo) of the cut surface of the tumor when exposed to dichromate. Pheochromocytomas most commonly arise from the adrenal medulla. Extraadrenally located pheochromocytomas are called paragangliomas, and arise from the paraganglion system. An adrenal pheochromocytoma is usually a rounded, gray-white, firm tumor 3 to 5 cm in diameter. When larger, they can adhere to adjacent structures, although still not metastasizing. Most pheochromocytomas are benign. However, approximately 10% of these tumors metastasize. It is almost impossible to differentiate a benign from a malignant tumor only by histological criteria. Classically only metastasized tumors are considered malignant for certain. Many attempts have been made to find markers that would predict the future behavior of an unmetastasized pheochromocytoma. In this overview of malignancy in pheochromocytomas, different steps of the tumorigenesis and several markers associated with them are discussed.

Pigmented composite paraganglioma-ganglioneuroma of the urinary bladder

We report a case of a pigmented composite paraganglioma-ganglioneuroma of the urinary bladder in a 70-year-old female. Grossly, the tumor measured 6.5 cm in diameter and had arisen from the base of the urinary bladder. Histologically, the tumor was composed of approximately equal components of paraganglioma and ganglioneuroma, which were partly separated and partly mixed, and intermingled with each other. There were foci of ample dark brown pigmentation in the cytoplasm of chromaffin paraganglioma cells. The pigment was Masson-Fontana-positive and had been bleached by hydrogen peroxide (H2O2). Electron microscopy showed large, abundant, pleomorphic electron-dense granules consistent with neuromelanin. In addition, there were numerous electron-dense neurosecretory-type granules. Neuromelanin, melanin or lipofuscin are occasionally observed in paragangliomas, although the occurrence of these pigments has never been described in a composite tumor originating from either adrenal medulla or extraadrenal paraganglia. To the best of our knowledge, our report represents the first case of pigmented composite paraganglioma-ganglioneuroma and expands the morphological spectrum of these unusual tumors.

Expression of the human telomerase reverse transcriptase in pheochromocytoma and neuroblastoma tissues

In an effort to clarify the role of telomerase in the pathogenesis of pheochromocytomas and neuroblastomas, and to test whether its component could serve as a marker of malignancy, we measured telomerase reverse transcriptase (TERT) mRNA in 31 human pheochromocytoma tissue samples (5 malignant, 23 benign and 3 suspected malignant) and 16 neuroblastoma tissues (9 unfavorable and 7 favorable). All cases were classified by both the clinical course and histopathological examination. Malignancy was defined as the presence of metastasis and/or extensive local invasion. TERT mRNA was determined by nested PCR and a real-time PCR system (LightCycler). By nested PCR methods, 5 of the 5 malignant pheochromocytoma samples were positive (sensitivity = 100%), and 21 of 23 benign pheochromocytoma samples were negative (specificity = 91%) in pheochromocytomas. Four out of five malignant tumors were positive for either hTERT expression or Ki-67/MIB-1 immunoreactivity. In the neuroblastoma tissues, 9 of the 9 unfavorable samples were positive (sensitivity = 100%), and only 2 of 7 favorable samples were negative (specificity = 29%). We also determined the expression of the hTERT mRNA by real-time PCR to quantitate the mRNA. The mean values of hTERT mRNA by real time PCR in benign and malignant pheochromocytomas were 2 and 26 arbitrary units (AU), respectively. The difference was not significant by the U-test. The mean values of hTERT mRNA in favorable and unfavorable neuroblastoma were 203 and 497 AU, respectively. This difference was also not significant (U-test). N-Myc mRNA expression correlated with the expression of hTERT mRNA in the neuroblastoma samples (r = 0.534, p = 0.0317). Thus, hTERT mRNA might be a potential marker for estimating the malignancy of pheochromocytomas and neuroblastomas.