A reappraisal of limited-stage undifferentiated carcinoma of the lung

Typical and Atypical Pulmonary Carcinoid Tumor Overdiagnosed as Small-Cell Carcinoma on Biopsy Specimens

Seven patients with typical or atypical pulmonary carcinoid tumors overdiagnosed as small-cell carcinoma on bronchoscopic biopsies are described. Bronchial biopsies from 9 consecutive small-cell lung carcinoma patients were used as control group for histologic and immunohistochemical studies (cytokeratins, chromogranin A, synaptophysin, Ki-67 [MIB-1], and TTF-1). The carcinoid tumors presented as either central or peripheral lesions composed of tumor cells with granular, sometimes coarse chromatin pattern, high levels of chromogranin A/synaptophysin immunoreactivity, and low (<20%) Ki-67 (MIB-1) labeling index. The tumor stroma contained thin-walled blood vessels. Small-cell carcinomas always showed central tumor location, finely dispersed nuclear chromatin, lower levels of chromogranin A/synaptophysin, and high (>50%) Ki-67 (MIB-1) labeling index. The stroma contained thick-walled blood vessels with glomeruloid configuration. Judging from this study, overdiagnosis of carcinoid tumor as small-cell carcinoma in small crushed bronchial biopsies remains a significant potential problem in a worldwide sample of hospital settings. Careful evaluation of hematoxylin and eosin sections remains the most important tool for the differential diagnosis, with evaluation of tumor cell proliferation by Ki-67 (MIB-1) labeling index emerging from our review as the most useful ancillary technique for the distinction.

The surgical spectrum of pulmonary neuroendocrine neoplasms

OBJECTIVES

The purpose of this study is to review our experience with the spectrum of neuroendocrine neoplasms of the lung with emphasis on the histopathologic classification and surgical therapy of each class of neoplasm.

DESIGN

This retrospective review covers the entire spectrum of neuroendocrine neoplasms of the lung over an 11-year period (January 1985 to December 1995) in a university hospital setting. Only patients who underwent surgical resection were included in this review.

PATIENTS

During this period, a total of 77 patients underwent lung resection for the following neuroendocrine neoplasms: typical carcinoid (TC), 50 patients; atypical carcinoid (AC), 5 patients; large cell neuroendocrine carcinoma (LCNEC), 9 patients; mixed large-small cell neuroendocrine carcinoma (LSNEC), 4 patients; or small cell neuroendocrine carcinoma (SCC), 9 patients. There were 37 men (48.1%) and 40 women (51.9%) among the patients, with a mean age of 57.9 years (range, 14 to 87 years).

INTERVENTIONS

Primary surgical resection consisted of the following procedures: 52 lobectomies (67.5%); 10 pneumonectomies (13%); 13 limited resections (16.9%); 1 left main bronchus sleeve resection; and 1 carinal resection. Six patients had the following concomitant procedures: pericardiectomy, 2 patients; mediastinoscopy, 1 patient; chest wall resection, 1 patient; stapling blebs, 1 patient; and transdiaphragmatic liver biopsy, 1 patient. Four patients underwent bilobectomies, and two patients underwent multiple wedge resections.

RESULTS

The hospital mortality rate was 2.6% (2 of 77 patients), and both patients died of pulmonary failure. Follow-up was obtained in 62 of 77 patients (80.9%) for an average of 38.1 months (range, 2 to 132 months). There were a total of 13 deaths, and 8 were disease-related (LCNEC, 4 deaths; SCC, 2 deaths; LSNEC, 1 death; and AC tumor, 1 death. The mean disease-free intervals for patients with these neoplasms were the following: TC tumor, 41.3 months; AC tumor, 20 months; LCNEC, 20.4 months; LSNEC, 25 months; and SCC, 48 months. The overall 3-year survival rate was 45.2% (28 of 62 patients).

CONCLUSION

This report will emphasize the classification, surgical management, and treatment considerations of pulmonary neuroendocrine neoplasms. Despite the poor overall prognosis in high-grade neuroendocrine tumors of the lung, surgery remains a viable adjunct in the early stages of this disease.

Surgery for small cell lung cancer

Operative management of small cell lung cancer generally yields little benefit because these tumors are known for their propensity to disseminate early to regional lymph nodes and distant sites. Primary surgery followed by chemotherapy is however indicated in very early stage tumors where survival approximates that of resected non small cell lung tumors. Surgery as an adjuvant to combination chemotherapy is also advocated by some authors to downstage the tumor and render it resectable. Candidates for salvage procedures include patients who have achieved complete response with chemotherapy, but subsequently relapsed within the chest at the site of the primary tumor.

Carcinoid tumors of the lung: do atypical features require aggressive management?

Atypical carcinoids are an intermediate form of tumor between low-grade malignant typical carcinoid and high-grade malignant small cell carcinoma, which represent the two ends of the spectrum of neuroendocrine bronchopulmonary tumors. Between 1983 and 1993, 27 patients with atypical carcinoids underwent surgical treatment. The histologic diagnosis of an atypical carcinoid was established if the criteria proposed by Arrigoni and associates were fulfilled. Seven pneumonectomies, 16 lobectomies, 2 segmentectomies, and 2 wedge resections were performed. Thirteen patients (48.1%) had regional nodal metastases and 6 patients (22%) had N2 disease at the time of surgical therapy. Distant metastases developed in 5 patients (18.5%) after initial treatment. The 10-year survival in patients with an atypical carcinoid was 49%, versus the 84% 10-year survival rate observed in patients with a typical carcinoid. We conclude that the aggressive behavior of atypical carcinoids precludes the use of limited surgical resection and requires a more aggressive approach, with lobectomy and mediastinal lymph node dissection constituting a minimal procedure. The same criteria used for well-differentiated lung carcinoma should apply to this form of neuroendocrine lung tumor. Adjuvant chemotherapy is recommended for patients with stage III or distant metastases.

Current treatment of unresectable lung cancer

The treatment of choice for most cases of non-small-cell lung cancer is surgical resection; however, which patients with stage IIIA disease are surgical candidates is debatable. For many patients with stage IIIA or IIIB disease, the preferred modality is thoracic radiotherapy. In several randomized prospective trials, the addition of chemotherapy to thoracic radiotherapy produced a significant but clinically small survival advantage over radiotherapy alone. For patients with stage IV lung cancer, no curative treatment or "standard therapy" is available. Accordingly, many patients are offered investigational agents in phase I or II clinical trials. Small-cell lung cancer has a 60 to 90% rate of initial response to available chemotherapeutic agents. Patients with limited disease are generally given combination chemotherapy and thoracic radiotherapy, approximately 50% of whom have a complete clinical remission. Patients with extensive disease (spread beyond one radiation port) also have a high rate of initial response to chemotherapy, but only 20 to 40% have a complete remission and few survive for 5 years. New agents are being tested in previously untreated patients with extensive small-cell lung cancer. Promising new chemotherapeutic agents for lung cancer are being studied in clinical trials. Currently, only 1% of patients with lung cancer in the United States are enrolled in prospective clinical trials. Primary-care physicians are urged to encourage their patients to consider participation in approved prospective clinical trials at reputable medical centers, in an effort to discover new, effective agents with novel mechanisms of action. Information about such studies is available through Physician Desk Query (PDQ) or the cancer hotline (1-800-4-CANCER).

Neuroendocrine differentiation in lung tumours

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Small cell lung cancer presenting as a solitary pulmonary nodule

Small cell lung cancer (SCLC) rarely presents radiographically as a solitary pulmonary nodule (SPN). Twenty-five patients with this feature were identified among 408 individuals with SCLC at McGill University (Montreal, Quebec) from 1979 through 1984. Of these, 15 (60%) were confirmed on pathologic review as SCLC (ten intermediate cell, four oat cell, one indeterminate). Pathologic review of a control group comprising 24 other limited-disease patients who were long-term survivors (greater than 20 months) confirmed 20 (84%) as SCLC (eight intermediate cell, 12 oat cell). Ten of the 15 patients with SPN were resected whereas five had chemotherapy and/or radiotherapy as primary treatment. Postoperative chemotherapy was administered to most of the resected patients. The median survival of the 15 patients with SPN was 24 months, a significantly longer survival than the other patients with SCLC. This improved prognosis in patients with SPN may be due to smaller initial tumor burden or to a fundamental biologic difference between SPN and other forms of SCLC.

Reevaluation of pulmonary neoplasms resected as small cell carcinomas. Significance of distinguishing between well-differentiated and small cell neuroendocrine carcinomas

The clinicopathologic features of 50 cases of surgically resected small cell carcinoma were reevaluated (doubly blinded). Two pulmonary carcinomas were excluded because neuroendocrine features could not be demonstrated; two additional cases also were excluded because the tumors grossly invaded the chest wall and their pulmonary origin was not substantiated. Thirty-four tumors were confirmed to be small cell neuroendocrine carcinoma (SCNC). Only seven of 11 (64%) patients with T1N0,T2N0 tumors survived more than 1 year; one of 11 (9%) patients survived more than 2 years. In 12 cases, the diagnosis was changed to well-differentiated neuroendocrine carcinoma (WDNC). Of these, nine of nine (100%) patients with T1N0,T2N0 tumors survived more than 1 year; six of eight (75%) patients survived more than 2 years. These observations strongly indicate that a significant number of long-term survivors with the diagnosis of small cell carcinoma may, in fact, have a distinctly less aggressive type of pulmonary neuroendocrine carcinoma. It was concluded that the distinction between small cell and well-differentiated types of neuroendocrine carcinomas has significant prognostic and therapeutic implications.

Well differentiated and small cell neuroendocrine carcinomas of the lung. Two related but distinct clinicopathologic entities

Twenty-two resected pulmonary well differentiated neuroendocrine carcinomas (WDNC) were re-evaluated histologically as were 28 resected intermediate-small cell neuroendocrine carcinomas (IC-SCNC). WDNC were distinguishable from IC-SCNC by their consistently recognizable organoid architecture, and by the absence or limited extent of necrosis. Furthermore, WDNC could be subclassified into 3 subsets based upon the degrees of pleomorphism, local and vascular invasion, and stromal fibrosis, the mitotic count, and the extent of tumor necrosis. Whereas all those parameters were important in discriminating between WDNC and IC-SCNC, the quality of the organoid architecture, and the extent and pattern of necrosis emerged as the most significant. WDNC with the more aggressive histologic features (subset III) had, as a group, a distinctly worse clinical course that those displaying blander features (subsets I and II). Nevertheless, even subset III of WDNC had, as a group, a longer survival than similarly treated Stages I and II IC-SCNC. We conclude that the histologic spectrum of WDNC is broader than generally recognized. Moreover, 3 subsets of WDNC are definable based on conventional histologic criteria provided sufficient, well preserved samples are examined. Even the most aggressive subset of WDNC can be thus histologically discriminated from IC-SCNC, and, given comparable stages, has a better prognosis than the latter.

Immunohistochemical evaluation of neuroendocrine cells and neoplasms of the lung

The dispersed neuroendocrine (NE) system is represented in the bronchopulmonary tract by submucosal nerves and ganglion cells and, in the mucosal lining by solitary NE cells and neuroepithalial bodies (NEB's). The latter two components variably express pan-NE markers including NSE, chromogranin (s) and, notably, synaptophysin. The expression of serotonin, bombesin, calcitonin and leu-enkephalin has been well established; additional eutopic materials include somatostatin and calcitonin gene-related peptide. Solitary NE cells and NEB's are epithelial structures as defined by their consistent cytokeratin expression. Hyperplasia and dysplasia of NE cells may be found in association with various forms of chronic injury; they have been noted in chronic bronchiectasis and in the vicinity of neoplasms of various types. Hyperplastic and dysplastic pulmonary NE cells frequently express ectopic materials particularly ACTH. NE neoplasms of the bronchopulmonary tract comprice a spectrum that includes a) carcinoids, b) well differentiated NE carcinomas, c) intermediate cell NE carcinomas and d) small cell NE carcinomas. The precise pathologic criteria defining these entities are discussed in detail as are their clinical implications. The entire spectrum of lung NE neoplasms express NE markers demonstrable by immunocytochemistry; these include pan-NE markers, serotonin and numerous neuropeptides. The expression of multiple hormonal materials is frequent. Within any given tumor, some variation in expression may be noted in different sites and in different periods of the "normal" or therapeutically modified lifespan of the tumor. The entire spectrum of lung NE neoplasms is epithelial for they express cytokeratin polypeptides and desmoplakin; subsets of the tumors coexpress cytokeratins and neurofilament proteins. Also, subsets of these NE neoplasms may be immunostained with monoclonal antibodies to antigens related to exocrine phenotype suggesting focal amphicrine features.

Peripheral small cell undifferentiated carcinoma of the lung. Clinicopathologic features of 17 cases

Seventeen cases of resectable peripheral small cell undifferentiated carcinoma of the lung were studied (average size, 2.1 cm; range, 0.9-3.5 cm). The carcinomas exhibited predominantly mixed intermediate and fusiform/spindle subtypes; in seven carcinomas there were at least some foci of oat cell subtype. There was no histologic evidence of typical carcinoid tumor. Seven cases were fixed in solutions appropriate for immunohistologic study; these exhibited prominent neuron-specific enolase activity but less prominent and more variable staining for the carcinoembryonic antigen and cytokeratins. All 17 cases were deemed resectable and had no clinical or radiologic evidence of metastasis. Seven (41%) patients died with recurrent and/or metastatic carcinoma (average survival, 1.7 years); five of these patients had carcinomas with at least some foci of oat cell foci subtype.