The prognostic significance of histologic subtyping in small cell carcinoma of the lung

Small cell carcinoma of the prostate. A morphologic and immunohistochemical study of 95 cases

Small cell carcinoma of prostate is rare, with the literature consisting of case reports and small series. The current work analyzes the morphology and immunohistochemistry of 95 cases of prostatic small cell carcinoma diagnosed at our institution. Specimens included 55 needle biopsies, 27 transurethral resections, 4 radical prostatectomies, and 9 biopsies from metastatic sites (some patients with >1 procedure). Patients ranged in age from 44 to 92 years old (mean: 69 y). Although serum prostate-specific antigen (PSA) in some cases was very high (up to 1896 ng/mL), the median value was only 4.0 ng/mL. Of cases with available information, 33/78 (42%) had a history of usual prostatic adenocarcinoma. The interval between the diagnosis of small cell carcinoma and prior usual prostatic cancer ranged from 1 to 300 months (median 25 mo). Pure small cell carcinoma was seen in 54/95 (57%) of cases with the remaining cases admixed with prostate adenocarcinoma. In cases with adenocarcinoma, there was a sharp demarcation between small cell carcinoma and adenocarcinoma in 20.5% of cases; in the remaining cases there was gradual merging of the 2 components. In mixed cases, small cell carcinoma predominated (median: 80% of the tumor); the Gleason score of the adenocarcinoma was > or =8 in 85% of these cases. In 61 cases (64%), small cell carcinoma was classic "oat cell" morphology with remaining the "intermediate cell" variant. Of the 95 cases: necrosis was seen in 40% (2% to 95% of the tumor); giant bizarre cells in 19%; Indian filing in 21%; rosette formation in 29%; focal vacuolated cytoplasm in 18%; and desmoplasia in 20%. Most (88%) of small cell carcinoma were positive for at least 1 neuroendocrine marker. In the small cell carcinoma component, 14/73 (19%) were positive for PSA, 17/61 (28%) positive for prostein (P501S), and 15/59 (25%) positive for prostate-specific membrane antigen, although often very focally. Stains for thyroid transcription factor-1 were positive in 23/44 (52.3%) cases. In this, the largest study of prostatic small cell carcinoma, we highlight the presence of morphologic features that may result in its underdiagnosis. Other more classic histologic features of small cell carcinoma along with rosettes are critical for its accurate diagnosis. P501S and prostate-specific membrane antigen were better in identifying the prostatic origin of small cell carcinoma than PSA, although the majority (60%) of prostatic small cell carcinomas were negative for all 3 markers.

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.

High-grade neuroendocrine carcinomas display unique cytogenetic aberrations

Neuroendocrine tumors represent a spectrum of tumor types with different biologic and clinical features. The morphologic types include the low-grade typical and atypical carcinoids and the high-grade small cell and large cell neuroendocrine carcinomas (NECs). Cytogenetic descriptions of high-grade NECs are rare. Complete karyotypic descriptions of 34 high-grade NECs are reviewed: 7 extrapulmonary small cell NECs, 3 metastatic NECs of unknown primary, and 24 small cell lung carcinomas (SCLCs). Chromosomal deletions are more frequent than gains and often involve the entire chromosome arm. Typical aberrations are deletions of chromosome 3p, 5q, 10q, and 17p and gains of 1q, 3q, and 5p occurring as isochromosomes. Non-small cell lung cancers (NSCLCs) have different cytogenetic aberrations, but those with a metastatic phenotype display the identical aberrations as SCLC, a tumor known for its metastatic phenotype at onset. A genetic classification of lung cancer that incorporates the pattern of recurrent chromosome aberrations may be a better predictor of clinical outcome than a morphologic classification.

Combined carcinoid tumor of the lung: a combination of carcinoid and adenocarcinoma

Combined small cell carcinoma is an uncommon but well described diagnostic category of neuroendocrine lung tumors. The prognosis of these tumors appears to be similar to that of pure small cell carcinoma, although it is believed that the non-small cell components of these tumors are less chemo-responsive than the small cell components. We report a case of a 60-year-old male smoker with a 2-cm nodule that, on subsequent lobectomy, was a combination of carcinoid and adenocarcinoma. A lymph node metastasis to an ipsilateral hilar node was comprised of only the well differentiated adenocarcinoma component. The biologic behavior of such tumors is not well described and their place within, what may be described as, a spectrum of combined neuroendocrine tumors is discussed.

Clinical relevance of histologic subtyping in small cell lung cancer

Histopathologic specimens from 249 patients with small cell lung cancer (SCLC) were reviewed and classified into oat cell-type, pure intermediate cell-type (excluding specimens with mixed small cell/large cell features), and small cell/large cell-type. One hundred seventy (68%) specimens displayed oat cell features (including 30 with mixed oat cell/intermediate cell features), 66 (27%) displayed intermediate cell features, and 13 (5%) displayed mixed small cell/large cell features. No differences among these subtypes were found with respect to stage of disease, sex, age, performance status, and number and distribution of metastases. Complete and partial remission rates for the oat cell-type were, respectively, 31% and 38%, for the intermediate cell-type 20% and 45%, and for the small cell/large cell-type 38% and 31%. Two-year survival rates were 7%, 11%, and 15%, respectively. These data were all statistically insignificant, and comparisons of log-rank analyses of survival curves for these SCLC subtypes also showed no statistically significant differences. We thus conclude that histologic subtypes of SCLC are not distinct entities of clinical relevance, and that prognostic as well as therapeutic decisions cannot be based on histologic subtyping.

Indications for surgical treatment in small cell carcinoma of the lung

Small cell carcinoma of the lung is notable for extreme malignancy in clinical behavior, with rapid growth, wide dissemination, and short survival after treatment. It is highly responsive to chemotherapy and radiation therapy, yet seldom cured. Prevalent therapeutic dogma rules out surgical resection as any part of treatment. We find, however, that patients with disease in stages I and II, treated with initial resection followed by the full course of chemotherapy, have a good prognosis for long disease-free survival.

Prevalence of neuroendocrine granules in small cell lung carcinoma. Usefulness of electron microscopy in lung cancer classification

Fifty-four lung carcinomas submitted for routine electron microscopy under the light microscopical diagnosis of small cell carcinoma were investigated. In 42 or of 45 evaluable cases, neuroendocrine granules were considered definitely or probably present, the modification 'probably' being necessary in suboptimal material. In three cases, squamous cell differentiation was seen, but no neuroendocrine granules were found. On revision of these three cases, the light microscopical diagnosis was changed to squamous cell carcinoma in one instance, and neither of the other two cases was considered classical for small cell carcinoma. Patient follow-up of these three cases showed tumour behaviour indicative of non-small cell carcinoma in two evaluable cases, the third case yielding no significant data. These results indicate that neuroendocrine granules can generally be found in small cell lung carcinomas, provided the material is sufficient for evaluation. When these granules are absent, and other differentiation is found on electron microscopy, the final classification of the tumour should incorporate this finding, to warn the clinician that the tumour will not necessarily behave as a small cell carcinoma.