Horseshoe kidney is associated with an increased relative risk of primary renal carcinoid tumor

PURPOSE: Carcinoid tumor is a rare neoplasm of the kidney with an unknown histogenesis. Of only 31 cases previously reported in the literature 4 arose within horseshoe kidneys. We report a case of primary carcinoid tumor arising within a horseshoe kidney and discuss the unique insight it provided into the pathogenesis of this tumor. MATERIALS AND METHODS: We reviewed in detail all 31 reported cases of renal carcinoid tumor and, using reported incidence rates of horseshoe kidney, we calculated the relative risk of renal carcinoid tumor arising within a horseshoe kidney. Immunohistochemical staining for neuroendocrine related markers was performed on tissue sections from the present carcinoid tumor, the adjacent kidney and 5 control samples of normal renal parenchyma. RESULTS: Of the reported tumors 15.6% occurred in horseshoe kidneys, yielding a calculated relative risk of 62. The present tumor was multifocal, arising from the wall of a cystic lesion and possibly representing a dilated calix within the isthmus. Intestinal epithelium lining the cyst cavity exhibited multifocal neuroendocrine cell hyperplasia with an immunohistochemical profile identical to that of the carcinoid tumor cells. CONCLUSIONS: The relative risk of renal carcinoid tumor developing in a horseshoe kidney is markedly greater than that for Wilms tumor or transitional cell carcinoma. The clinical course of renal carcinoid tumor arising within a horseshoe kidney appears to be more benign than that of the nonhorseshoe variant. Our observations support the hypothesis that renal carcinoid tumors may arise from neuroendocrine cells within foci of metaplastic or teratomatous epithelium within the kidney.     

Genotator: a workbench for sequence annotation

The clinical, pathological, and immunohistochemical features of six cases of metastatic neuroendocrine and carcinoid tumors to the thyroid simulating medullary thyroid carcinoma (MTC) are described. The patients were women between the ages of 24 and 70 years who, without symptoms or significant past medical histories, presented with either a single mass or multiple thyroid nodules. The primary source of the tumor was only discovered on follow-up. Two of the neoplasms were classical carcinoid tumors, one was a carcinoid predominantly composed of large cells, another showed a prominent oval to spindle cell component, and the two remaining cases were atypical carcinoid/high-grade neuroendocrine carcinomas. The immunohistochemical profile was inconsistent with MTC in that all tumors were negative for calcitonin and only two were focally positive for carcinoembryonic antigen (CEA). A variable pattern of staining for other neuroendocrine and epithelial markers was obtained in each case. Despite the morphologic and immunohistochemical similarities with MTC, the diagnosis of a metastatic neuroendocrine tumor to the thyroid should be favored in the presence of a predominantly interstitial pattern of spread; occurrence of multiple tumor foci; folliculotropism; rosette formations with lumen and cuticular borders; and lack of immunoreactivity for calcitonin and CEA. The differential diagnosis between MTC and metastatic neuroendocrine carcinoma to the thyroid is of importance because of the vast differences in treatment and prognosis.     

Precursors to pulmonary neoplasia

Squamous dysplasia in the bronchi has been long recognized as a precursor of lung carcinoma, particularly squamous carcinoma. Atypical adenomatous hyperplasia (AAH) has been recently implicated as a precursor to adenocarcinoma. Bronchiolar neuroendocrine cell hyperplasia has also been suggested as a precursor to some pulmonary carcinoid tumors. The atypical adenomatous hyperplasia-adenocarcinoma sequence has been likened to the adenoma-carcinoma sequence in the large intestine. AAH is commonly multifocal, and may explain multicentricity that is observed with some adenocarcinomas. AAH has been shown to have immunohistochemical, morphometric, flow cytometric and genetic abnormalities overlapping with adenocarcinoma. Bronchiolar neuroendocrine cell hyperplasia (carcinoid tumorlets) is classically associated with inflammatory lesions in the airways, but may also be multifocal and bilateral. In the latter setting, lesions may attain a size greater than 0.5 cm and be (arbitrarily) classified as carcinoid tumors.     

Immunohistologic analysis of gastrointestinal and pulmonary carcinoid tumors

Carcinoid tumors are potentially malignant neoplasms that arise in various body sites, including the lung and gastrointestinal tract. Those that appear cytologically atypical are more likely to behave aggressively than more typical carcinoid tumors. However, in the absence of cytological atypia or large tumor size, it is difficult to predict the biology of an individual tumor, because some lesions metastasize, whereas others do not. This study had four aims: (1) To study the expression pattern of p53, Ki-67, NCAM, and S-100 in carcinoid tumors and to relate these expression patterns to classical histopathologic features and to tumor location. (2) To identify nonhistological markers that might more accurately predict the early behavior of carcinoid tumors. (3) To determine whether sustentacular cells are present in carcinoid tumors arising in tissues derived from different embryological derivatives. (4) To determine the synaptophysin and chromogranin immunoreactivity in neuroendocrine tumors arising in various locations. The immunostaining reactions were quantitatively scored by three observers. Only 3 of the 39 tumors (all histologically atypical) were strongly positive for Ki-67; two of these were also strongly p53 immunoreactive. NCAM immunostaining differed according to the site of origin: 76.5% of foregut lesions, 58% of the midgut lesions, and 20% of hindgut lesions were positive. S-100 immunostaining ranged from 41% in foregut lesions to 50% in both the hindgut- and midgut-derived tumors. S-100-positive sustentacular cells were present in 20.5% of carcinoid tumors. All tumors stained with antibodies against synaptophysin. In contrast, 100% of midgut, 60% of hindgut, and 88% of foregut tumors were chromogranin positive. Carcinoid tumors tend to have low proliferative rates. p53 immunostaining tends to be strongly positive in tumors that are histologically atypical, but it is negative in typical carcinoid tumors arising in the gastrointestinal tract and lungs. Immunostaining reactions with antibodies to NCAM, S-100, and chromogranin differ depending on the site of origin. Synaptophysin stains 100% of carcinoid tumors regardless of their site of origin. In contrast, antibodies to chromogranin fail to stain 40% of hindgut tumors and 12% of foregut carcinoid tumors. S-100-positive sustentacular cells are present in foregut and midgut tumors but not in hindgut tumors.     

Optic nerve metastasis from a mediastinal carcinoid tumour

A 25-year-old man with a rapidly progressive metastatic carcinoid tumour arising in the mediastinum developed a metastasis to the optic nerve. This is the first instance in the literature of an ocular metastasis from this variant of carcinoid tumour. The ocular pathology, ultrastructure, and recent information on the derivation of this tumour, believed to originate in the thymus, are presented.     

Ectopic thymic carcinoid masquerading as a thyroid nodule

A 26-year old woman presented with a thyroid nodule. Ultrasound and scintigraphy confirmed the presence of a 3.5-cm non-functioning mass in the left lobe. A fine needle aspiration demonstrated unusual, malignant-appearing cells, and thyroidectomy was performed. At gross pathological sectioning, the lesion was clearly attached to, but not part of, the thyroid. Microscopic features indicated an atypical carcinoid arising in a cervical remnant of the thymus. This appears to be the first case of ectopic thymic carcinoid presenting as a thyroid nodule.     

Lymphocytes in host defense against Pneumocystis carinii

To determine the neuroendocrine (NE) features of thymic epithelial tumor, immunohistochemistry and electron microscopy studies were performed on eight NE tumors (thymic carcinoids) and 26 non-NE tumors (nine thymic carcinomas, five atypical thymomas, and 12 thymomas other than lymphocytic thymoma). Immunohistochemical studies were performed with antibodies against general markers for NE cells (synaptophysin, alpha subunit of a guanine nucleotide-binding protein, Go, and small-cell lung carcinoma cluster 1 antigen), and a broad panel of antibodies for hormonal substances. Thymic carcinoid showed synchronous diffuse immunoreactivity for the three NE markers and contained cells that were positive for a variety of hormonal products: human chorionic gonadotropin (hCG) alpha-subunit (eight of eight), hCG beta-subunit (three of eight), adrenocorticotropic hormone (ACTH) (three of eight), calcitonin (two of eight), calcitonin gene-related peptide (two of eight), and serotonin (one of eight). Conversely, although positivity for NE markers was neither synchronous nor diffuse in non-NE tumors, seven of nine thymic carcinomas, three of five atypical thymomas (focal or dispersed distribution), and none of the five thymomas were positive for at least two of these NE markers. A small number of neoplastic cells were positive for hCGalpha-subunit or ACTH in three thymic carcinomas and one atypical thymoma. Ultrastructurally, dense core granules (DCG) were much more frequent in thymic carcinoid, but several DCG-like granules were identified in 12 of 13 non-NE tumors with or without immunoexpression of NE markers. The presence of focal or dispersed NE cells in thymic carcinoma and atypical thymoma may reflect multidirectional differentiation within the tumor, which, like cytological atypia, epithelial CD5 expression, and lack of immature T cell infiltration, may be another feature of this group at thymic tumors.     

Neuroendocrine differentiation is a common feature of thymic carcinoma

Immunohistochemical evidence of neuroendocrine differentiation in the form of reactivity for synaptophysin, neuron-specific enolase, and/or chromogranin was found in 11 of 19 (58%) thymic carcinomas having the typical morphologic features of that tumor type. Four of these 19 cases were studied ultrastructurally, and neuroendocrine-type cytoplasmic dense-core granules were found in two. In contrast, 84 thymomas were negative for these markers, except for a focal immunoreactivity for neuron-specific enolase in areas of medullary differentiation in half of the lymphocyte-rich tumors. The results of this study show that in the thymus, similar to most other organs, neuroendocrine differentiation is not limited to tumors with an identifiable neuroendocrine appearance in hematoxylin-eosin-stained slides, such as carcinoid tumor and small cell carcinoma, but rather that it represents a common event shared by the major types of malignant epithelial tumors of that organ.     

Small-cell neuroendocrine carcinoma of the uterine cervix associated with micro-invasive squamous cell carcinoma and adenocarcinoma in situ

A case of small-cell neuroendocrine carcinoma of the uterine cervix associated with squamous cell carcinoma and adenocarcinoma in situ is reported. The tumor consisted mainly of uniform small cells with a population of intermediate cells that resembled carcinoid tumor cells. Foci of micro-invasive squamous cell carcinoma and adenocarcinoma in situ were recognized separately, adjacent to the main tumor. Both Grimelius stain and immunostaining of serotonin were positive for small-cell and intermediate-cell carcinoma. Neurosecretory granules were demonstrated by electron microscopy. Microacini with positive mucin staining and microvilli-like structures suggested glandular or exocrine differentiation of the tumor. Three distinctive types of differentiation, neuroendocrine, exocrine and squamous characteristics, were expressed in the tumor.     

Exfoliative cytology of invasive neuroendocrine small cell carcinoma in a cervical cytologic smear. A case report

BACKGROUND: Neuroendocrine small cell carcinoma of the cervix (NSC) is cytologically identical to its counterparts at other sites, such as the lung, and can be suspected on a cervical cytologic smear. It has to be distinguished from poorly differentiated nonkeratinizing squamous small cell carcinoma, adenocarcinoma with carcinoid features, embryonal neuroblastoma, embryonal rhabdomyosarcoma, stromal sarcoma and non-Hodgkin's lymphoma. CASE: An 18-year-old woman had invasive NSC. Exfoliative cytology of the cervix showed tumor cells, single or in small clusters and files, with darkly staining nuclei. The chromatin pattern was coarse, with small, prominent chromocenters, and the nuclei were often invisible. The cytoplasm was so reduced as to be barely discernible. Mutual molding of adjacent nuclei was frequent. Immunohistochemistry showed positive staining for pancytokeratin and neuron-specific enolase. Flow cytometry showed aneuploidy, with a DNA index of 1.93. CONCLUSION: The cytologic appearance of NSC in a cervical cytologic smear is characteristic. The diagnosis, nevertheless, has to be proven by the identification of neuroendocrine differentiation.     

Neuroendocrine carcinomas of the larynx

Neuroendocrine carcinomas of the larynx are uncommon tumors. They include typical carcinoid tumors, atypical carcinoid tumors and small cell neuroendocrine carcinomas. The diagnosis is based on light microscopy which demonstrate evidence of neurosecretory granules, and on histochemical and immunohistochemical investigations. The histogenesis, treatment and prognosis factors are discussed.     

Neuroendocrine tumours in various organ systems in a ten-year period

Neuroendocrine cells are present in various organ systems. These widely distributed cells as well as their histogenetically related tumours can produce various peptides and peptide hormones. From 1984 to 1993, 349 neuroendocrine tumours were found among 511,382 histological diagnoses at the Institute of Pathology of the Medical School of the Karl Franzens University in Graz. In 30% carcinoid of the appendix was diagnosed, in 16% carcinoid of the colorectum, in 9% carcinoid of the small intestine and in 2% duodenal carcinoid. Carcinoid of the stomach was detected in 14%. Seven of these cases showed microcarcinoidosis and five of them were combined with an adenocarcinoma. Carcinoid of the oesophagus was present in 1%, neuroendocrine pancreatic tumours in 6%. Neuroendocrine tumours of the bronchial system were found in 12%, medullary thyroid cancer in 5%. In 1% a Merkel-cell tumour was diagnosed. Other more rare localizations of neuroendocrine tumours were the uterus, ovary, breast, testes, epididymis, anal region and the upper respiratory tract.     

Unbalanced chromosomal aberrations in neuroendocrine lung tumors as detected by comparative genomic hybridization

Typical and atypical carcinoids (TC, ATC) and small (SCLC) and large cell neuroendocrine carcinomas (LCNEC) constitute the spectrum of neuroendocrine lung tumors. Chromosomal aberrations have not been studied in LCNEC and only rarely in carcinoids. Only SCLCs have been investigated frequently for chromosomal aberrations. We compared three typical and four atypical carcinoids, one atypical carcinoid/SCLC mixed type, three SCLC, and three LCNEC for chromosomal gains and losses using comparative genomic hybridization. Typical carcinoids showed either no changes or only few chromosomal gains. Atypical carcinoids appeared genetically heterogeneous: One case had no aberrations, and three cases had few aberrations; two of them showed a deletion of 11q. SCLC and LCNEC were characterized by many gains and losses, especially similar changes of 3p, 5q, 5p, and 13q. Although ATC resemble LCNEC morphologically, there were no similarities at the genetic level. We have found a reciprocal relationship of prognosis and the amount of aberrations. TCs and ATCs with few chromosomal changes have the best prognosis, whereas SCLCs and LCNECs were generally characterized by a great amount of aberrations and worst prognosis. There was no unbalanced aberration common in all types of neuroendocrine tumors of the lung.     

Ancrod: understanding the agent

Five primary ovarian carcinomas composed of a high-grade neuroendocrine tumor of non-small-cell type and a surface-epithelial-stromal tumor are reported. The five tumors presented in women aged 36 to 77 (mean, 57) years with abdominal distension or a palpable mass in three cases, right lower quadrant pain with tenderness and fever in one case, and a cervicovaginal smear showing a high estrogen effect in one postmenopausal patient. The tumors were unilateral, 9 to 30 (mean, 16) cm in greatest dimension, and had solid and cystic components. Three tumors were stage I; one, stage II; and one, stage III. Two patients who received chemotherapy died of tumor 8 and 36 months postoperatively, another who refused chemotherapy but later received radiation died of tumor after 19 months, a fourth was lost to follow-up, and a fifth was treated recently. Microscopically, the neuroendocrine components of all the tumors were composed predominantly of sheets, closely packed islands, cords, and trabeculae of epithelial cells with little intervening stroma. The tumor cells in the neuroendocrine areas were medium-sized to large compared with the cells of small cell carcinoma, and they contained scanty to moderate amounts of cytoplasm and hyperchromatic nuclei with coarse chromatin clumping in three cases and abundant cytoplasm and vesicular nuclei with single, large eosinophilic nucleoli in the other two. In all the cases, areas of necrosis and single-cell necrosis were extensive, and mitotic figures were abundant. Positive argyrophil and argentaffin reactions were observed in occasional to many cells in all cases. The glandular components of the tumors were grade 1/3 endometrioid adenocarcinoma (one case), grade 2/3 mucinous adenocarcinoma (2 cases), and mucinous borderline tumor with small foci of mucinous adenocarcinoma (two cases). Numerous enterochromaffin cells were identified in hematoxylin and eosin sections of the borderline mucinous components of two tumors; occasional nonargentaffin argyrophilic cells were present in the endometrioid and mucinous carcinoma components. Luteinized stromal cells were present focally in two cases, including the case in which there was evidence of a high estrogen level. Immunohistochemical studies in five cases showed staining of most cells in the solid components for cytokeratin and chromogranin A and some to most cells for serotonin and neuron-specific enolase. Neuropeptides that were detected in the solid component of one or more of the cases included vasoactive intestinal peptide, somatostatin, gastrin, and glucagon; negative results were obtained for pancreatic polypeptide and insulin. Flow cytometry in four tumors revealed that the neuroendocrine component was aneuploid in two, suspicious for aneuploidy in one, and diploid in one. Tumors of the type described are distinct pathologically from primary ovarian carcinoid tumors and small cell carcinoma of pulmonary type. Although experience with this type of tumor is limited, the prognosis appears to be poor.     

Merkel cell carcinoma of the skin

Primary neuroendocrine carcinoma of the skin or Merkel cell carcinoma is an aggressive primary neoplasm. It is commonly seen in the elderly, on the head, neck and extremities, where it can mimic a benign or less malignant skin tumour. Pathological examination shows a generally dense growth of small dark cells, with immunohistochemical evidence of neuroendocrine differentiation. The microscopic appearance is very similar to metastatic oat cell carcinoma from the lung and this must be excluded by clinical means and appropriate imaging studies. In this study we present 13 new cases of Merkel cell carcinoma (the largest published series in the UK) and summarize 214 cases from the literature in which the survival data are given. In our series, 5 of 13 patients died from spread of the Merkel cell carcinoma. From this and other studies, it appears that early diagnosis and wide local excision may be the only way to prolong survival. No other adjuvant therapy has proved effective.     

Bronchopulmonary atypical carcinoid tumour metastatic to the orbit

BACKGROUND: Bronchopulmonary carcinoid tumours metastatic to the orbit are rare. A case is presented demonstrating presentation, histopathology and treatment. METHODS: A 64-year-old man with a history of bronchopulmonary atypical carcinoid presented with an orbital mass. The nature of this metastasis was confirmed with histology and it was surgically excised and, in addition, local radiotherapy and chemotherapy were administered. RESULTS: There was a good response to the treatment for the orbital mass but other metastases developed, causing death. CONCLUSIONS: In this case of atypical carcinoid, orbital metastasis was the first sign of disease progression. Histological confirmation of the diagnosis was important in this case to allow planning of oncological therapy and for appropriate patient counselling. A good local response was obtained with a combination of surgical excision, local radiotherapy and chemotherapy. The systemic prognosis remains poor in cases of metastatic bronchopulmonary atypical carcinoid tumour, in contrast to typical carcinoid.     

Neuroendocrine differentiated carcinoma of the uterine cervix

Cervical neuroendocrine carcinomas (CNC) are rare tumors. The term includes the cervical carcinoid, the small cell (oat-cell) carcinoma and the primitive neuroectodermal tumor (PNET). Between 1979 and 1993 eight CNC out of 788 cervical carcinomas were identified by conventional light microscopy and immunohistochemistry. Three tumors were small cell carcinomas with positive staining for NSE (6/8 tumors) and chromogranin A (2/8). In one case a PNET was diagnosed by identifying rosette like structures and negative immunohistochemistry for neuroendocrine markers. Two patients (including PNET) died of disease 3.1 (1.3 to 4.8) years after diagnosis. The others showed no evidence of disease after a mean follow up to 4.4 years. Three of them got pelvic radiation postoperatively. Four tumors showed foci of squamous cell carcinoma [3] and adenocarcinoma [2]. There is no evidence, that these foci influence the prognosis on CNC. Therefore, it is important to recognize the neuroendocrine component, as this type of carcinoma requires special therapeutic considerations. The authors favour the metaplastic origin of CNC from a multipotent (endocervical) stem cell.     

Large cell neuroendocrine [corrected] carcinoma of the uterine cervix: a clinicopathologic study of 12 cases

Twelve cervical tumors showing morphologic evidence of neuroendocrine differentiation and lesional cells larger than those of typical small cell carcinoma are reported in women 21 to 62 (mean 34) years of age. The patients presented with an abnormal Papanicolaou smear or vaginal bleeding. Two tumors were stage Ia2, nine were stage Ib, and one was stage IIa. All patients were treated by radical hysterectomy, and most received adjuvant chemotherapy. Seven of 10 patients with > 1 year of follow-up died of tumor 6 to 24 months after hysterectomy. The tumors had insular, trabecular, glandular, and solid growth patterns and contained medium to large cells with moderate to abundant cytoplasm; eosinophilic cytoplasmic granules were present in nine cases. The tumors were mitotically active, and necrosis was present in 10 of them. Nine of 10 tumors were argyrophilic, and all 12 were immunoreactive for chromogranin. Individual cells containing somatostatin, serotonin, or glucagon were identified in four of eight cases. Adenocarcinoma in situ was present adjacent to the tumor in eight cases; invasive adenocarcinoma of non-neuroendocrine type was present in three of these tumors. Using diagnostic criteria established for pulmonary neuroendocrine tumors, the 12 tumors were classified as large cell neuroendocrine carcinomas. Cervical large cell neuroendocrine carcinomas are distinctive cervical carcinomas that are frequently misdiagnosed and have an unfavorable outcome, similar to that of small cell carcinoma.     

How should drugs for anxiety be prescribed?

For a tumor classification scheme to be useful, it must be reproducible and it must show clinical significance. Classification of neuroendocrine lung tumors is a difficult problem with little information about interobserver reproducibility. We sought to evaluate the classification of typical carcinoid (TC), atypical carcinoid (AC), large-cell neuroendocrine carcinoma (LCNEC), and small-cell carcinoma (SCC) tumors as proposed by W.D. Travis et al (Am J Surg Pathol 15:529, 1991). Forty neuroendocrine tumors were retrieved from the Armed Forces Institute of Pathology (AFIP) files and independently evaluated by five lung pathologists and classified as TC, AC, LCNEC, or SCC (pure SCC, mixed small cell/large cell, and combined SCC). A single hematoxylin and eosin-stained slide from each case was reviewed. Each participant was provided a set of tables summarizing the criteria for separation of the four major categories. Agreement was regarded as unanimous if all five pathologists agreed, a majority if four agreed, and a consensus if three or more pathologists agreed. The kappa statistic was calculated to measure the degree of agreement between two observers. A consensus diagnosis was achieved in all 40 cases (100%), a majority agreement in 31 of 40 (78%), and unanimous agreement in 22 of 40 (55%) of cases. Unanimous agreement occurred in seven of SCC (70%), seven of TC (58%), four of AC (50%), and four of LCNEC (40%). A majority diagnosis was achieved in 11 of 12 (92%) of TC, 9 of 10 (90%) of SCC, 6 of 8 (75%) of AC, and 5 of 10 (50%) of LCNEC. Most of the kappa values were 0.70 or greater, falling into the substantial agreement category. The most common disagreements fell between LCNEC and SCC, followed by TC and AC, and AC and LCNEC. The highest reproducibility occurred for SCC and TC, with disagreement in 8% and 10% of the diagnoses, respectively. For TC, 10% of the diagnoses rendered were AC. For AC, 15% of the diagnoses were rendered as TC, with 2.5% called LCNEC and 2.5% called SCC. For LCNEC, 18% and 4% of the diagnoses were called SCC and AC, respectively. For SCC, 4% of the diagnoses were called AC and 4% were called LCNEC. Thus, using the classification scheme tested, a consensus diagnosis can be achieved for virtually all neuroendocrine lung tumors with substantial agreement between experienced lung pathologists. Classification of NE tumors is most reproducible for classification of TC and SCC but less reproducible for AC and LCNEC. These results indicate a need for more careful definition and application of criteria for TC versus AC and SCC versus LCNEC.     

Neural cell adhesion molecules (NCAM) and NCAM-PSA expression in neuroendocrine lung tumors

Neural cell adhesion molecules (NCAM) represent specific markers of neuroendocrine (NE) differentiation in lung cancer. Because the polysialic acid form (NCAM-PSA) has reduced adhesion properties, we hypothesized that NCAM-PSA expression could favor metastatic spread. Immunostaining of NCAM and NCAM-PSA were therefore compared in 120 NE lung tumors, including 17 typical carcinoids, 3 atypical carcinoids, 30 large cell NE carcinomas and 70 small cell lung carcinomas, as compared with 25 adenocarcinomas and 25 squamous cell carcinomas. Neural cell adhesion molecules were negative in adenocarcinomas and squamous cell carcinomas but were constantly expressed in all NE tumors from typical carcinoids to small cell lung carcinomas. NCAM-PSA expression was significantly more frequent in high-grade tumors, with 24 of 30 positive cases in large cell NE carcinomas and 65 of 70 positive cases in small cell lung carcinoma, than in carcinoids with 10 of 17 and 2 of 3 positive cases in typical carcinoids and atypical carcinoids, respectively. The neural cell adhesion molecule-polysialic acid form scores of staining were significantly higher in high-grade as compared with low-grade tumors (p = 0.002), and were correlated with nodal spread (p = 0.04) and metastasis (p = 0.016) across histologic classes but not in individual tumor type. We conclude that NCAM-PSA connotes poor differentiation and aggressive clinical behavior in the spectrum of NE lung tumors, but cannot be regarded as a prognostic factor in individual tumor classes.