Cytopathological spectrum of peripheral neuroblastic tumours in fine needle aspiration cytology and categorisation as per International Neuroblastoma Pathology Classification.

OBJECTIVE: The aim of this analysis was to describe the cytopathology spectrum of peripheral neuroblastic tumours (NTs) including neuroblastoma (NB), ganglioneuroblastoma (GNB) and ganglioneuroma (GN). Feasibility of applying the International Neuroblastoma Pathology Classification (INPC) to further subtype NTs in cytology was evaluated. METHODS: All peripheral NTs reported on fine needle aspiration during 2011-2015 were retrieved and detailed cytomorphological evaluation was performed. Based on INPC criteria, NBs were further categorised as undifferentiated, poorly differentiated and differentiating subtypes. Mitotic-karyorrhectic index was evaluated. Immunocytochemistry on cell blocks was reviewed wherever available. MYCN amplification by fluorescence in situ hybridisation was performed in 11 cases on smears. RESULTS: A total of 90 cases including 83 NBs, six GNB and one GN were evaluated. The age range was 12 days-12 years, with 55 males and 45 females. Both the primary and metastatic locations were aspirated. Applying the INPC criteria, there were 61 poorly differentiated, 14 undifferentiated, eight differentiating NB and six GNB. Immunocytochemistry on cell blocks showed positivity for at least two neuronal markers in NB. Mitotic-karyorrhectic index was high in 63, low in 22 and intermediate in two cases, respectively. MYCN amplification by fluorescence in situ hybridisation was feasible on smears and was amplified in 6 out of 11 cases tested. CONCLUSION: Peripheral NT types including NB, GNB and GN have distinctive cytomorphology. NBs can be further subtyped as undifferentiated, poorly differentiated and differentiating subtypes as per INPC criteria.

Association of MYCN copy number with clinical features, tumor biology, and outcomes in neuroblastoma: A report from the Children's Oncology Group.

BACKGROUND: High-level MYCN amplification (MNA) is associated with poor outcome and unfavorable clinical and biological features in patients with neuroblastoma. To the authors' knowledge, less is known regarding these associations in patients with low-level MYCN copy number increases. METHODS: In this retrospective study, the authors classified patients has having tumors with MYCN wild-type tumors, MYCN gain (2-4-fold increase in MYCN signal compared with the reference probe), or MNA (>4-fold increase). Tests of trend were used to investigate ordered associations between MYCN copy number category and features of interest. Log-rank tests and Cox models compared event-free survival and overall survival by subgroup. RESULTS: Among 4672 patients, 3694 (79.1%) had MYCN wild-type tumors, 133 (2.8%) had MYCN gain, and 845 (18.1%) had MNA. For each clinical/biological feature, the percentage of patients with an unfavorable feature was lowest in the MYCN wild-type category, intermediate in the MYCN gain category, and highest in the MNA category (P<.0001), except for 11q aberration, for which the highest rates were in the MYCN gain category. Patients with MYCN gain had inferior event-free survival and overall survival compared with those with MYCN wild-type. Among patients with high-risk disease, MYCN gain was associated with the lowest response rate after chemotherapy. Patients with non-stage 4 disease (according to the International Neuroblastoma Staging System) and patients with non-high-risk disease with MYCN gain had a significantly increased risk for death, a finding confirmed on multivariable testing. CONCLUSIONS: Increasing MYCN copy number is associated with an increasingly higher rate of unfavorable clinical/biological features, with 11q aberration being an exception. Patients with MYCN gain appear to have inferior outcomes, especially in otherwise more favorable groups. Cancer 2017;123:4224-4235. © 2017 American Cancer Society.

Fine-needle aspiration of ganglioneuroma, maturing type (a.k.a., "borderline ganglioneuroblastoma") in the mediastinum of a young man: Case report and discussion of classification.

We report a very unusual case of a posterior mediastinal tumor in a young man, which we diagnosed by fine-needle aspiration cytology as most consistent with ganglioneuroma, maturing subtype. The cytopathologic features were interpreted using the classification of neuroblastic tumors as defined by the International Neuroblastoma Pathology Committee. Neuroblastic tumors are peculiar tumors that have capacity for maturation, and hence they present as a spectrum of tumors, ranging from the undifferentiated neuroblastoma, to ganglioneuroblastoma, to the mature version ganglioneuroma. The practicing surgical pathologist or cytopathologist who does not regularly encounter pediatric specimens may experience difficulty interpreting a specimen from one of these tumors. The following case report discusses application of these criteria to cytopathologic diagnosis of these tumors.

[Neurogenic tumors of the mediastinum in adults]. / Tumeurs nerveuses du médiastin de l'adulte.

In adults, mediastinal neurogenic tumours constitute the third group of mediastinal tumours, after thymomas and lymphomas. If the group of neurogenic tumour is frequent, each type of tumour is relatively unusual in everyday's clinic. Among them, nerve sheath tumours are the more frequent, followed by tumour of the autonomic system. Askin tumour remains uncommon. Treatment of this tumour requires complete preoperative work-up, including standard radiography, CT-scan, MRI, and sometimes nuclear imaging. In most cases, the treatment is based on surgical resection, and may be associated with radiotherapy or chemotherapy in case of malignant tumour or incomplete resection. Better understanding of these tumours, including their molecular abnormalities, may lead to new changes in their classifications, and to their management.

Results of surgical treatment of cervical dumbbell tumors: surgical approach and development of an anatomic classification system.

STUDY DESIGN: A retrospective study of a new classification and surgical approach of cervical dumbbell tumors. OBJECTIVE: To evaluate PUTH classification. SUMMARY OF BACKGROUND DATA: The high recurrence rate and postoperative deformity are unsolved problems. Asazuma's landmark classification could not cover all cases and could not provide clear suggestion for the surgical approach. The ideal classification should be comprehensive, easily understood and of practical value. METHODS: PUTH classification for cervical dumbbell tumors includes 7 categories (types 1-7) and 2 foraminal modifiers. Posterior approach is appropriate for type 1, 2 and 5 tumors, anterior and anterolateral approach is an ideal choice for type 4 and 6 tumors. Type 7 tumors need combined anterior and posterior approach. RESULTS: Forty-four consecutive patients with cervical dumbbell tumor were surgically treated. The pathology included schwannoma in 31 cases, neurofibroma in 9 and ganglioneuroma in 4. Based on PUTH classification, type 3 was diagnosed in 13 cases, type 5 in 17, type 6 in 8, and type 7 in 6. Tumors were unilateral in 41 cases, and bilateral in 3 cases. Five were tumor revision cases. Thirty patients underwent posterior approach, 7 had anterior approach, 1 had anterolateral approach, and 6 had combined approach. Gross total resection was achieved in all the patients. Tumors involved nerve roots were transected in 12 cases. Single vertebral artery was ligated in 3. The complications included cerebrospinal fluid leakage in 18 cases, esophagus injury in 1, Horner syndrome in 1, dysphagia in 2, dyspnea in 1 and deep infection in 1. Thirty-six cases (81.1%) had an average 61-month follow-up. Recurrence was found in only one case (2.8%). CONCLUSION: PUTH classification covers all tumor types and is easier to remember. It is practical and useful for determining the surgical approach. The recurrence rate decreases significantly after radial tumor resection. Revision surgeries are associated with more complications.

Retrospective study of childhood ganglioneuroma.

PURPOSE: To review a historical cohort of childhood ganglioneuroma (GN), the benign representative of the peripheral neuroblastic tumor (PNT) family. PATIENTS AND METHODS: Of 2,286 PNTs enrolled between 1979 and 2005, 146 (6.4%) were registered as GN. Histological revision was carried out on 76 tumors. Diagnosis was confirmed in 45, while 27 were reclassified as ganglioneuroblastoma intermixed (GNBI) and four were reclassified as other PNT subtypes. RESULTS: GNs differed from other PNTs for sex, age, tumor site, stage, tumor markers, and scintigraphic results. Characteristics of 76 reviewed and 70 nonreviewed patients were comparable. Reviewed GN and GNBI patients were comparable except for homovanillic acid excretion, metaiodobenzylguanidine scintigraphy, and DNA content. Seven patients were only biopsied and 139 underwent surgery. Twenty-two patients suffered surgery-related complications, of which two were fatal and seven were severe. Radical tumor resection and surgery-related complication rates were comparable for GN, GNBI, and nonreviewed instances. Six patients developed tumor progression but survived. Two patients developed a late malignancy but survived. None of the 146 patients received chemotherapy. Of 146 patients, two died of surgery-related complications and 144 survived. CONCLUSION: Diagnosis was changed to GNBI for approximately one third of 76 reviewed tumors. Patients with confirmed GN, reclassified as GNBI, and nonreviewed histology presented with comparable clinical, biochemical, and biologic features. Surgical results, complication rate, number of progressions, and outcome were similar for the three groups. Surgery was associated with significant risk of complications. Survival was not influenced by extent of tumor resection. Aggressive surgical approach should not be recommended for childhood GN and GNBI.

Ganglion cell containing pituitary adenomas: signs of neuronal differentiation in adenoma cells.

Ganglion cell containing pituitary adenomas are rare. They represent tumors originating in the sella turcica which are composed of adenomatous and neuronal components. Recently accumulated information suggests a common origin for their neuronal and pituitary constituents. The objective of this study was to report the clinical and morphologic findings of pituitary gangliocytomas and study their immunoprofile using neuronal markers. Seven cases of pituitary gangliocytomas retrieved from 1,322 sellar lesions were studied. All tumors were removed from patients with mild acromegaly. Histologically they were biphasic composed of pituitary adenoma and clusters of ganglion cells embedded in a variably dense neuropil substrate. All adenomas belonged to the category of sparsely granulated somatotroph adenoma and were positive for growth hormone, whereas in five tumors, a few adenoma cells were also positive for prolactin. Ganglion cells were immunoreactive for NSE, synaptophysin and neurofilament protein (NFP). NFP-reactive fibrils were observed in the neuropil substrate and varied in number among the cases. Interestingly, all tumors contained varying numbers of adenoma cells with NFP-positive, dot-like areas of cytoplasmic reactivity, mostly tiny paranuclear, a finding not previously reported in human pituitary gangliocytomas. The presence of NFP in pituitary adenomas indicates neuronal differentiation in adenoma cells, suggesting a common origin for neuronal and pituitary adenoma cell elements in gangliocytomas.

Pathologic classification of peripheral nerve tumors.

Peripheral nerve tumors show an interesting histologic variety despite being composed ofa limited array of cellular constituents. As we learn more about the interplay between the Schwann cells, perineurial cells, and ganglion cells that comprise these tumors, it is likely that we will better understand the biologic behavior of these important tumors. Key issues for the pathologist include distinguishing schwannomas from neurofibromas, ganglioneuromas from neurofibromas involving ganglia, and MPNSTs from cellular schwannomas or neurofibromas. The association of each of these tumors with genetic tumor disorders provides a unique window into discovering basic mechanisms of cell regulation and tumorigenesis that may ultimately shed light on the biology of a much wider array of human disease.

[Peripheral neuroblastic tumors: anatomo pathological classification]. / Les tumeurs neuroblastiques périphériques, classification anatomo-pathologique.

Peripheral Neuroblastic Tumors are classified according to the recommendations of the INPC into four categories and their subtypes: 1/Neuroblastoma stroma poor, undifferentiated, poorly differentiated, and differentiating, 2/ganglioneuroblastoma stroma composite, nodular, 3/ganglioneuroblastoma stroma composite, intermixed and 4/ganglioneuromas stroma dominant, maturing and mature. The classification is based on age and morphologic features of PNT, including the differentiation grade of the neuroblasts and the mitosis-karyorrhexis index. Histopathological classification has prognostic impact in predicting overall and event-free survival allowing the categorisation of PNT into two groups: favorable subset and unfavorable subset.

Lhermitte-Duclos disease (dysplastic cerebellar gangliocytoma): a malformation, hamartoma or neoplasm?

OBJECTIVES: Dysplastic gangliocytoma (Lhermitte-Duclos disease) is a rare disorder, characterized by a slowly progressive unilateral tumour mass of the cerebellar cortex. The fundamental nature of this apparently benign entity and in particular its pathogenesis remain unknown. The debate, whether it represents a neoplastic, malformative or hamartomatous lesion, is still in progress. Lhermitte-Duclos disease was recently encountered to be part of a multiple hamartoma-neoplasia complex (Cowden's syndrome). METHODS: The present account gives a review of the pertinent literature with emphasize on clinical presentation, radiological findings, surgical procedures, histopathological features and pathogenetic considerations of dysplastic cerebellar gangliocytoma. RESULTS: Dysplastic cerebellar gangliocytoma clusters within the third to fourth decades of life. Cranial nerve palsies, unsteadiness of gait, ataxia and sudden neurological deterioration as a result of occlusive hydrocephalus are frequent signs and symptoms. Associations with other congenital malformations, such as megalencephaly, polydactylia, multiple haemangioma and skull abnormalities are common. Magnetic resonance imaging (MRI) is the diagnostic modality of choice and reveals characteristic non-enhancing gyriform patterns with enlargement of cerebellar folia. Surgery is the therapeutic procedure generally performed and complete resection was attempted in the majority of cases. The histopathological findings of Lhermitte-Duclos disease include widening of the molecular layer, which is occupied by abnormal ganglion cells, absence of the Purkinje cell layer and hypertrophy of the granule cell layer. CONCLUSIONS: Dysplastic gangliocytoma of the cerebellum is of benign behaviour and its incidence is extremely rare. The disease should be considered when confronted with a young adult presenting with clinical signs of progressive mass effect in the posterior fossa. The lesion is hypointense on T1- and hyperintense on T2-weighted magnetic resonance images. Recognition of the disease is of particular importance, as the frequent but under-reported coexistence with Cowden syndrome, should prompt thorough clinical and apparative investigation to detect or exclude concomitant malignancies.

Maturation of mass-screened localized adrenal neuroblastoma.

BACKGROUND/PURPOSE: In infants, neuroblastoma has been known to spontaneously differentiate into a benign ganglioneuroma. Although several investigators have compared mass-screened with unscreened, disseminated with localized, and adrenal with retroperitoneal neuroblastoma, there are very few cross-comparisons of the above parameters. Herein, the authors report the maturation of mass-screened, localized adrenal neuroblastoma. METHODS: Fifty-one mass-screened adrenal neuroblastomas were divided into 2 groups. In infants less than 1 year of age (Group A), 45 neuroblastomas were resected, whereas 6 neuroblastomas were resected after observation in 1- to 4-year-old children (group B). Histopathology of the tumors in the 2 groups was compared. Data were analyzed by X(2) test, and P <.05 was considered significant. RESULTS: According to the International Neuroblastoma Pathological Classification, 41 of 45 tumors of group A were "differentiating neuroblastoma" and 4 of 6 tumors of group B were "maturing ganglioneuroma." Maturation toward ganglioneuroblastoma was observed in 16 neuroblastomas of group A (36%) and 6 neuroblastomas of group B (100%). In group A, 58% had low mitosis karyorrhexis index (MKI); all patients in group B had low MKI. CONCLUSIONS: If left untreated, maturation of mass-screened, localized adrenal neuroblastomas is a common phenomenon. These children do not need to undergo early operation.

Telomerase activity distinguishes between neuroblastomas with good and poor prognosis.

BACKGROUND: Treatment of neuroblastoma has remained a major challenge in pediatric oncology because the assessment of the individual prognosis, particularly in disseminated disease is still obscure. Previous studies have correlated clinical outcome with activity levels of telomerase, a cellular reverse transcriptase which has been detected in the majority of human malignant tumors. PATIENTS AND METHODS: In this blind-trial study, a non-radioactive telomeric repeat amplification protocol (TRAP) with an internal telomerase-assay standard was used on an automated laser fluorescence sequencer for the detection and semiquantitative analysis of telomerase activity (TA) in 67 neuroblastomas of all clinical stages from the German Neuroblastoma Trial and 2 ganglioneuromas. TA levels were correlated with event-free and overall survival rates and established prognostic markers such as MYCN. RESULTS: TA was present in 14 of 69 (20%) samples, including 3 of 22 stage IVS, 8 of 14 stage IV, 1 of 10 stage III, 1 of 7 stage II and 1 of 14 stage I neuroblastomas and 0 of 2 ganglioneuromas. We found a strong statistical correlation between the presence of TA and poor clinical prognosis with regard to all tumor stages. Multivariate analysis revealed TA as an independent prognostic marker. In particular, the analysis of TA in IVS neuroblastomas distinguished two different prognostic groups. CONCLUSIONS: Our data suggest that TA is an independent prognostic marker in neuroblastoma which, in combination with other markers such as MYCN, may proof useful in assessing the individual patient's prognosis.

Terminology and morphologic criteria of neuroblastic tumors: recommendations by the International Neuroblastoma Pathology Committee.

BACKGROUND: As part of the international cooperative effort to develop a complete set of International Neuroblastoma Risk Groups, the International Neuroblastoma Pathology Committee (INPC) initiated activities in 1994 to devise a morphologic classification of neuroblastic tumors (NTs; neuroblastoma, ganglioneuroblastoma, and ganglioneuroma). METHODS: Six member pathologists (H.S., I.M.A., L.P.D., J.H., V.V.J., and B.R.) discussed and defined morphologically based classifications (Shimada classification; risk group and modified risk group proposed by Joshi et al.) on the basis of a review of 227 cases, using various pathologic characteristics of the NTs. The classification-grading system was evaluated for prognostic significance and biologic relevance. RESULTS: The INPC has adopted a prognostic system modeled on one proposed by Shimada et al. It is an age-linked classification dependent on the differentiation grade of the neuroblasts, their cellular turnover index, and the presence or absence of Schwannian stromal development. Based on morphologic criteria defined in this article, NTs were classified into four categories and their subtypes: 1) neuroblastoma (Schwannian stroma-poor), undifferentiated, poorly differentiated, and differentiating; 2) ganglioneuroblastoma, intermixed (Schwannian stroma-rich); 3) ganglioneuroma (Schwannian stroma-dominant), maturing and mature; and 4) ganglioneuroblastoma, nodular (composite Schwannian stroma-richlstroma-dominant and stroma-poor). Specific features, such as the mitosis-karyorrhexis index, the mitotic rate, and calcification, were also included to allow the prognostic significance of the classification to be tested. Recommendations are made regarding the surgical materials to use for an optimal pathobiologic assessment and the practical handling of samples. CONCLUSIONS: The current article covers the essentials and important points regarding the histopathologic evaluation of NTs. Using the morphologic criteria described herein, the INPC is proposing the International Neuroblastoma Pathology Classification. It is reported in a companion article in this issue (Cancer 1999;86:363-71).

The International Neuroblastoma Pathology Classification (the Shimada system).

BACKGROUND: The International Neuroblastoma Pathology Committee, which is comprised of six member pathologists, was convened with the objective of proposing a prognostically significant and biologically relevant classification based on morphologic features of neuroblastic tumors (NTs) (i.e., neuroblastoma, ganglioneuroblastoma, and ganglioneuroma). METHODS: A total of 227 cases were reviewed. Consensus diagnoses from morphologic features (criteria described separately) based on five of six or six of six agreements by the reviewer pathologists were used for prognostic analysis. Prognostic effects of morphology, both individual and in combination, taken in conjunction with age (Shimada classification, histologic grade, and risk group), were analyzed. RESULTS: Approximately 99% of cases (224 of 227) had consensus diagnoses for categorization: neuroblastoma (Schwannian stroma-poor), 190 cases; ganglioneuroblastoma, intermixed (Schwannian stroma-rich), 5 cases; ganglioneuroma (Schwannian stroma-dominant) maturing, 1 case; ganglioneuroblastoma, nodular (composite Schwannian stroma-rich/stroma-dominant and stroma-poor), 19 cases; and NT-unclassifiable, 9 cases. For the NTs, subtype (93% consensus: undifferentiated, 6 cases; poorly differentiated, 155 cases; and differentiated, 15 cases), mitosis-karyorrhexis index (90% consensus: low, 94 cases; intermediate, 40 cases; and high, 37 cases), mitotic rate (75% consensus: low, 89 cases; high, 50 cases; and not determined, 4 cases), and calcification (100% consensus: yes, 110 cases and no, 80 cases) were recorded. Statistical analysis demonstrated that the Shimada classification system (90% consensus; 3-year event free survival: 85% for the group with favorable histology and 41% for the group with unfavorable histology; P = 0.31 x 10(-9)) had a significantly stronger prognostic effect than individual features and other combinations. CONCLUSIONS: The International Neuroblastoma Pathology Classification, a system based on a framework of the Shimada classification with minor modifications, is proposed for international use in assessing NTs.

Comparison of ultrastructural features among neuroblastic tumors: maturation from neuroblastoma to ganglioneuroma.

Neuroblastic tumors have the unique ability to differentiate and mature. This family of tumors is composed of the neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. These tumors are derived from primordial neural crest cells that form the sympathetic nervous system. The purpose of this study was to characterize the ultrastructural features of neuroblastic tumors in a pediatric population. Forty-five neuroblastic tumors (15 neuroblastomas, 15 ganglioneuroblastomas, and 15 ganglioneuromas) were examined using standard transmission electron microscopic techniques. Undifferentiated neuroblastomas were composed of primitive cells with rare neurite-like processes containing clear secretory vesicles and no Schwann cell differentiation. Poorly differentiated and differentiating neuroblastomas showed more frequent neuritic processes with infrequent dense core granules and infrequent immature Schwann-like cells. Ganglioneuroblastomas possessed an admixture of cell types, including immature ganglion cells without associated satellite cells, intermediate cells, and differentiating neuroblasts. The neuropil contained immature Schwann cells encasing haphazardly arranged neuritic processes. Ganglioneuromas were composed of mature ganglion cells with occasional binucleation. The neuropil contained mature Schwann cells with well-organized neuritic processes and abundant collagen deposition. Differentiation or maturation of tumor cells, neuritic processes, and Schwann cells may thus be discerned ultrastructurally in primary neuroblastic tumors in pediatric patients.

Systematization of primary histopathologic and fine-needle aspiration cytologic features and description of unusual histopathologic features of neuroblastic tumors: a report from the Pediatric Oncology Group.

On the basis of a detailed review of the primary histopathologic features of 239 cases and the fine-needle aspiration cytologic features of seven cases, a systematized schema of differentiation, progressive maturation and organization, and biologic behavior in neuroblastic tumors (NTs) is presented. The differentiation is of the gangliocytic and schwannian lineages. Maturation occurs in differentiating neuroblasts, leading to the formation of various stages of ganglion cells and Schwann cells. Organization is characterized by nesting pattern, rosette formation, parallel arrangement of neuropil, and alignment of Schwann cells along the neurites. According to this schema the NTs can be arranged in the following order: undifferentiated, poorly differentiated, and differentiating neuroblastoma; nodular, intermixed, and borderline ganglioneuroblastoma; and ganglioneuroma. Formulation of such a schema is helpful in gaining a better understanding of the complex pathologic features and in defining the criteria for various types of NTs. Therefore, the schema also would be helpful in achieving uniformity and reproducibility of the diagnosis of various types of NTs. Previously unreported features related to shape, size, nucleus, and cytoplasm of neuroblasts; secondary changes and patterns; changes in the fibrovascular septa; and other morphologic aspects of NTs and features (such as large tumor cells, karyorrhectic cells in fine-needle aspiration biopsy, tumor giant cells, anaplasia, and nesting pattern of tumor cells that have not been sufficiently emphasized) also are described. The importance of these previously unreported and insufficiently emphasized features relates to the histologic and cytologic diagnosis of NTs. For example, some of the features, such as starry sky appearance and spindle-shaped neuroblasts, may be misleading if seen in a small biopsy specimen. Others, such as tumor giant cells resembling ganglion cells and nesting pattern, will provide clues to the correct diagnosis. Some of the features, such as sclerosing pattern, hyalinization, and dense lymphoplasmacytic infiltration, may be related to the phenomenon of regression exhibited by neuroblastomas.

Tumors of the neuroblastoma group.

The basic histologic changes associated with the maturational sequences of neuroblastoma tumors are reviewed. The author describes a histopathologic classification system developed for distinguishing favorable and unfavorable prognoses, based on the combination of tumor morphology and patient's age at diagnosis. Also discussed are the results of recent analyses of the biologically significant relationship between histologic findings and molecular markers, such as amplification of the N-myc oncogene and expression of the nerve growth factor receptor gene. Clinical trials involving neuroblastoma tumors are briefly reviewed.

Recommendations for modification of terminology of neuroblastic tumors and prognostic significance of Shimada classification. A clinicopathologic study of 213 cases from the Pediatric Oncology Group.

To develop consistency in terminology and pathologic criteria, the authors reviewed the literature and 213 cases of neuroblastic tumors (NT) registered with Pediatric Oncology Group (POG) protocols 8104 and 8441. The patients were given standardized therapy stratified according to POG stage and patient age, and four or more histologic sections of primary tumor resected before therapy were available in each of these 213 cases. All stages were represented. The recommended nomenclature combines conventional terms and criteria with those used by Bove and McAdams and Shimada et al. The main features of the recommended nomenclature are as follows: (1) the terms neuroblastoma (NB) and ganglioneuroblastoma (GNB) are retained instead of stroma-poor NB and stroma-rich NB, recommended by Shimada et al.; (2) undifferentiated NB is considered a subtype separate from poorly differentiated NB; and (3) the term GNB is used only when there is a predominant ganglioneuromatous component admixed with the minor neuroblastomatous component. With the use of these criteria and terms, the Shimada classification was determined in the 213 cases. The results showed that, even after stratification for age, POG stage, and primary site, there is a statistically significant difference in survival rate between favorable histologic and unfavorable histologic prognostic subgroups. The authors recommend that definitive prognostic categorization of an NT according to Shimada classification should be done only when adequate histologic material is available from a primary tumor resected before any other therapy. Categorization done on histologic material from small biopsy specimens, previously treated primary tumors, or metastatic sites should be considered tentative.