Small cell carcinoma of the prostate. A morphologic and immunohistochemical study of 95 cases. Am J Surg Pathol. 2008;32:65-71. [PMID: 18162772 DOI: 10.1097/PAS.0b013e318058a96b]

Pathology reporting of neuroendocrine tumors: essential elements for accurate diagnosis, classification, and staging

Much recent debate has focused on the optimal classification of epithelial neuroendocrine tumors (NETs). Multiple different systems of terminology, grading, and staging have been proposed, and some systems combine elements of grade and stage into a single prognostic classification. Recently, national and international consensus groups have attempted to standardize the classification of NETs, especially for those arising in the gastrointestinal tract and pancreas. Furthermore, the recognition that common classification criteria (such as proliferative rate) span multiple different systems allows the basic data necessary to predict outcome and tailor therapy to be included in pathology reports, even though a single uniform system of terminology may remain elusive. Formal tumor-node-metastasis (TNM)-based staging systems also have been developed recently, and advances in the treatment of some NETs (pancreatic in particular) are pointing towards the need to assess therapeutic biomarkers in routine practice. This review will present the most widely used systems for classifying, grading, and staging NETs and will summarize the recommendations for the data to be included in standard pathology reports of these uncommon tumors.

Value of thyroid transcription factor-1 immunostaining in tumor diagnosis: a review and update

Thyroid transcription factor-1 (TTF-1) is a tissue-specific transcription factor that plays a critical role in the normal development of embryonic epithelial cells of the thyroid and lung. Because TTF-1 expression is highly restricted to epithelial tumors arising in these organs, it is, at present, one of the immunohistochemical markers most commonly used to assist in the differential diagnosis of carcinomas of the lung and thyroid. Recent studies, however, have reported that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought as it can be found to be expressed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Even though this unexpected TTF-1 positivity has been reported more frequently with the recently available SPT24 anti-TTF-1 monoclonal antibody, it has also been shown to occur with the commonly used 8G7G3/1 clone, albeit in a lower percentage of cases. Despite these findings, TTF-1 remains a very useful immunohistochemical marker in diagnostic pathology.

Small cell carcinoma of the urinary bladder: a rare, aggressive neuroendocrine malignancy

Small cell carcinoma of the urinary bladder is a rare, often fatal, disease. Its presenting symptoms and gross morphology are similar to those of conventional urothelial carcinoma, whereas its prognosis is much poorer with frequent metastasis. Small cell carcinoma of the urinary bladder shares similar histology with its counterparts in other organs; however, its immunoreactivity to conventional neuroendocrine markers is low. Its diagnosis is thus considered permissible on morphologic grounds alone. Multimodal treatments are often employed, although no definite treatment algorithm has been established. For this extremely aggressive malignancy with an as-yet inconclusive etiology, further studies are needed to clarify its molecular pathogenesis to serve as a basis for diagnostic markers and therapeutic targets. The clinical, morphologic, immunoreactive, molecular, and therapeutic features of bladder small cell carcinoma are reviewed, including a detailed discussion on the utility of immunohistochemical markers.

Clinical impact of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of small cell carcinoma of the prostate

Small cell carcinoma of prostate (PSCC) is an uncommon and aggressive type of prostate malignancy with limited data on the use of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in the clinical management of this rare entity. In this report, clinical and imaging findings of a patient with PSCC are presented. We aimed to discuss the role of PET/CT in the evaluation of PSCC in combination with histopathological characteristics of tumor and emphasize the importance of PET/CT in the clinical management of PSCC.

Molecular characterization of neuroendocrine prostate cancer and identification of new drug targets

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that most commonly evolves from preexisting prostate adenocarcinoma (PCA). Using Next Generation RNA-sequencing and oligonucleotide arrays, we profiled 7 NEPC, 30 PCA, and 5 benign prostate tissue (BEN), and validated findings on tumors from a large cohort of patients (37 NEPC, 169 PCA, 22 BEN) using IHC and FISH. We discovered significant overexpression and gene amplification of AURKA and MYCN in 40% of NEPC and 5% of PCA, respectively, and evidence that that they cooperate to induce a neuroendocrine phenotype in prostate cells. There was dramatic and enhanced sensitivity of NEPC (and MYCN overexpressing PCA) to Aurora kinase inhibitor therapy both in vitro and in vivo, with complete suppression of neuroendocrine marker expression following treatment. We propose that alterations in Aurora kinase A and N-myc are involved in the development of NEPC, and future clinical trials will help determine from the efficacy of Aurora kinase inhibitor therapy.

SIGNIFICANCE

We report on the largest in-depth molecular analysis of NEPC and provide new insight into molecular events involved in the progression of prostate cancer.

Small cell cancer of the prostate

De novo small cell cancer of the prostate is a rare tumor and has different presentation, behavior, and outcome compared with adenocarcinoma. A 66-year-old man presented with symptoms masquerading as a rectal tumor. Primary symptoms were intermittent constipation and diarrhea without any urinary symptoms. Initial staging showed only 2 large pelvic nodes. Prostate-specific antigen was 4.8 ng/L. A transrectal prostate biopsy confirmed small cell histology. After having no response to hormones and carboplatin-etoposide, a course of palliative radiotherapy, docetaxel chemotherapy, and defunctioning colostomy offered palliation. Liver and lytic bone metastases developed later; the patient died 9 months after the presentation.

Small cell-like change in prostatic intraepithelial neoplasia, intraductal carcinoma, and invasive prostatic carcinoma: a study of 7 cases

Small cell carcinoma of the prostate is associated with poor prognosis and different treatment from conventional acinar adenocarcinoma. Given the important clinicopathologic implications of a diagnosis of small cell carcinoma, we report 7 cases showing unusual, extensive small cell-like change in intraductal carcinoma and invasive carcinoma. Prostatic biopsies from 3 patients and radical prostatectomy specimens from 4 patients showed variably extensive small cell-like high-grade prostatic intraepithelial neoplasia and intraductal carcinoma. Five cases were associated with conventional acinar adenocarcinoma (2 cases with Gleason score 4 + 3 = 7; 3 cases with Gleason 3 + 4 = 7). No small cell carcinoma was seen. Small and large ducts with small cell-like change showed solid and cribriform proliferations of atypical cells with abrupt transition between centrally located populations of small cells and more typical large dysplastic cells at the duct periphery. Rosette-like formations were noted within some involved ducts. Small cell-like change was characterized by crowded cells with uniformly bland vesicular nuclei and minimal cytoplasm and no significant mitotic or apoptotic activity. In 3 cases, similar small cell-like morphology was noted focally in invasive carcinoma. The small cell-like areas were negative for synaptophysin and chromogranin, focally positive for TTF-1, and weakly positive for racemase. Ki-67 labeled less than 5% with predominant labeling of the larger atypical cells and minimal reactivity in the small cell-like population. In summary, small cell-like change in prostatic intraepithelial neoplasia, intraductal carcinoma, and invasive carcinoma is not associated with small cell carcinoma; shows no immunohistochemical evidence of neuroendocrine differentiation; and likely is not an adverse prognostic feature.

Pure small cell carcinoma of the prostate: A rare tumor

Pure small cell carcinoma of the prostate is a rare and aggressive neoplasm, with only few cases described in literature and poor prognosis: mean survival is 5 months. We report the case of a patient with this disease, with special attention to the evolution of neuroendocrine markers as Chromogranine A and neuron-specific enolase during the progression of the tumor, evaluating their possible role in staging and follow up.

Small cell neuroendocrine carcinoma of the prostate: incidence and a report of four cases with an examination of KIT and PDGFRA

Because there have been no reports on the incidence and expressions and mutations of KIT and PDGFRA in small cell neuroendocrine carcinoma (SCNEC) of the prostate, the author surveyed archival specimens of 2,642 prostatic specimens (biopsy, 1,503 cases; transurethral resection, 1,009 cases; prostatectomy, 130 cases). Of these, 706 cases were malignant tumors. In equivocal cases (n = 16) of Gleason 5 adenocarcinoma resembling SCNEC, several neuroendocrine markers were immunohistochemically examined. As the results, four cases of SCNEC were identified; therefore the incidence of SCNEC was 0.5% of all prostatic malignancies. All the four cases were biopsies. The remaining 686 cases were adenocarcinomas. In case 1 (50 years of age), the SCNEC tumor cells were positive for cytokeratin, P504S, synaptophysin, KIT, and PDGFRA, but negative for PSA, neuron specific enolase, CD56, and TTF-1. In case 2 (70 years of age), the tumor cells were positive for cytokeratin, PSA, P504S, chromogranin, and synaptophysin, but negative for neuron-specific enolase, CD56, TTF-1, KIT, and PDGFRA. In case 3 (72 years of age), the SCNEC tumor cells were positive for cytokeratin, PSA, P504S, synaptophysin, CD56, KIT, and PDGFRA, but negative for neuron-specific enolase, chromogranin, and TTF-1. In case 4 (81 years of age), the SCNEC tumor cell were positive for cytokeratin, PSA, P504S, chromogranin, synaptophysin, neuron-specific enolase, KIT, and PDGFRA, but negative for CD56 and TTF-1. A molecular genetic analysis using PCR-direct sequencing showed no mutations of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12 and 18) genes in three informative cases of SCNEC. The present cases were the first of prostatic SCNEC with an examination of KIT and PDGFRA expression and KIT and PDFGRA gene mutations.

Extrapulmonary small cell carcinoma: a clinicopathological study with identification of potential diagnostic mimics

AIMS

To evaluate the clinicopathological features of small cell carcinoma arising outside the lung.

METHODS AND RESULTS

Thirty-seven cases with a pathology diagnosis of extrapulmonary small cell carcinoma (EPSCC) were selected. The clinical notes were reviewed and tumour blocks were selected for a fresh haematoxylin and eosin (H&E) section and immunohistochemical stains. The most common tumour locations were cervix and bladder. Twenty-five cases (68%) were finally diagnosed as EPSCC, nine of which were found with coexisting non small cell carcinoma. Two cases (5%) were diagnosed as large cell neuroendocrine carcinoma (LCNEC) of the cervix. The remainder was classified as 10 poorly differentiated carcinomas (PDCs) (27%). Positive staining for thyroid transcription factor 1 (TTF-1) was noted in nine cases of EPSCC and in none of the cases of PDC (P = 0.034). Synaptophysin immunoreactivity was found in 20 cases of EPSCC and two cases of PDC with neuroendocrine differentiation (P = 0.002), as well as two cases of LCNEC. 34βE12 was positive in eight cases of SCC and two cases of PDC.

CONCLUSIONS

Based on this series, EPSCC may be overdiagnosed. Immunohistochemistry for TTF-1, used in combination with synaptophysin, may help to discriminate EPSCC from PDC.

Pathogenesis of prostatic small cell carcinoma involves the inactivation of the P53 pathway

Small cell neuroendocrine carcinoma (SCNC) of the prostate is a variant form of prostate cancer that occurs de novo or as a recurrent tumor in patients who received hormonal therapy for prostatic adenocarcinoma. It is composed of pure neuroendocrine (NE) tumor cells, but unlike the scattered NE cells in benign prostate and adenocarcinoma that are quiescent, the NE cells in SCNC are highly proliferative and aggressive, causing death in months. In this study, we provide evidence that interleukin 8 (IL8)-CXCR2-P53 (TP53) signaling pathway keeps the NE cells of benign prostate and adenocarcinoma in a quiescent state normally. While P53 appears to be wild-type in the NE cells of benign prostate and adenocarcinoma, immunohistochemical studies show that the majority of the NE tumor cells in SCNC are positive for nuclear p53, suggesting that the p53 is mutated. This observation is confirmed by sequencing of genomic DNA showing p53 mutation in five of seven cases of SCNC. Our results support the hypothesis that p53 mutation leads to inactivation of the IL8-CXCR2-p53 signaling pathway, resulting in the loss of an important growth inhibitory mechanism and the hyper-proliferation of NE cells in SCNC. Therefore, we have identified potential cells of origin and a molecular target for prostatic SCNC that are very different from those of conventional adenocarcinoma, which explains SCNC's distinct biology and the clinical observation that it does not respond to hormonal therapy targeting androgen receptor signaling, which produces short-term therapeutic effects in nearly all patients with prostatic adenocarcinoma.

Complete chemotherapeutic regression of a non-metastatic case of primary pure small cell carcinoma of the prostate

Pure small cell carcinoma of the prostate (SCPCa) is a very rare condition usually with poor survival after diagnosis. It seems to show different clinical features compared to other prostate cancer subtypes, specifically adenocarcinoma. Here, we present a 74-year-old man early diagnosed with SCPCa treated with a cisplatine and etoposide regimen. There was no metastasis found in imaging studies and bone scan. The patient mostly complained of obstructive symptoms which were relieved after resection. Interestingly, our patient experienced a disease free condition after chemotherapy and no further progression was found. This could implicate the critical role of early diagnosis in the treatment of SCPCa despite its aggressive nature.

Modeling a lethal prostate cancer variant with small-cell carcinoma features

PURPOSE

Small-cell prostate carcinoma (SCPC) morphology predicts for a distinct clinical behavior, resistance to androgen ablation, and frequent but short responses to chemotherapy. We sought to develop model systems that reflect human SCPC and can improve our understanding of its biology.

EXPERIMENTAL DESIGN

We developed a set of castration-resistant prostate carcinomas xenografts and examined their fidelity to their human tumors of origin. We compared the expression and genomic profiles of SCPC and large-cell neuroendocrine carcinoma (LCNEC) xenografts to those of typical prostate adenocarcinoma xenografts. Results were validated immunohistochemically in a panel of 60 human tumors.

RESULTS

The reported SCPC and LCNEC xenografts retain high fidelity to their human tumors of origin and are characterized by a marked upregulation of UBE2C and other mitotic genes in the absence of androgen receptor (AR), retinoblastoma (RB1), and cyclin D1 (CCND1) expression. We confirmed these findings in a panel of samples of CRPC patients. In addition, array comparative genomic hybridization of the xenografts showed that the SCPC/LCNEC tumors display more copy number variations than the adenocarcinoma counterparts. Amplification of the UBE2C locus and microdeletions of RB1 were present in a subset, but none displayed AR nor CCND1 deletions. The AR, RB1, and CCND1 promoters showed no CpG methylation in the SCPC xenografts.

CONCLUSION

Modeling human prostate carcinoma with xenografts allows in-depth and detailed studies of its underlying biology. The detailed clinical annotation of the donor tumors enables associations of anticipated relevance to be made. Future studies in the xenografts will address the functional significance of the findings.

Lactate MRSI and DCE MRI as surrogate markers of prostate tumor aggressiveness

Longitudinal studies of lactate MRSI and dynamic contrast-enhanced MRI were performed at 4.7 T in two prostate tumor models grown in rats, Dunning R3327-AT (AT) and Dunning R3327-H (H), to determine the potential of lactate and the perfusion/permeability parameter Ak(ep) as markers of tumor aggressiveness. Subcutaneous AT (n = 12) and H (n = 6) tumors were studied at different volumes between 100 and 2900 mm(3) (Groups 1-5). Lactate concentration was determined using selective multiple quantum coherence MRSI with the phantom substitution method. Tumor enhancement after the administration of gadolinium diethylenetriaminepenta-acetic acid was analyzed using the Brix-Hoffmann model and the Ak(ep) parameter was used as a measure of tumor perfusion/permeability. Lactate was not detected in the smallest AT tumors (Group 1; 100-270 mm(3) ). In larger AT tumors, the lactate concentration increased from 2.8 ± 1.0 mm (Group 2; 290-700 mm(3)) to 8.4 ± 2.9 mm (Group 3; 1000-1340 mm(3)) and 8.2 ± 2.2 mm (Group 4; 1380-1750 mm(3) ), and then decreased to 5.0 ± 1.7 mm (Group 5; 1900-2500 mm(3)), and was consistently higher in the tumor core than in the rim. Lactate was not detected in any of the H tumors. The mean tumor Ak(ep) values decreased with increasing volume in both tumor types, but were significantly higher in H tumors. In AT tumors, the Ak(ep) values were significantly higher in the rim than in the core. Histological hypoxic and necrotic fractions in AT tumors increased with volume from 0% in Group 1 to about 20% and 30%, respectively, in Group 5. Minimal amounts of hypoxia and necrosis were found in H tumors of all sizes. Thus, the presence of lactate and heterogeneous perfusion/permeability are signatures of aggressive, metabolically deprived tumors.

Small cell carcinoma of the kidney: a clinicopathologic study of 14 cases

Small cell carcinoma of the kidney is distinctively rare. We searched pathology files in 2 institutions and found 14 cases of renal small cell carcinoma. The patients' mean age at diagnosis was 59 years (range, 22-75 years); 8 were women, and 6 were men. Patients usually presented with hematuria (n = 6) and abdominal pain (n = 5). The mean tumor size was 7.1 cm (range, 3.5-14.0 cm). The small cell carcinoma was pure in 9 cases and mixed with high-grade urothelial carcinoma in 5 cases. None was associated with any type of renal cell carcinoma. Tumor necrosis was present in all cases, and lymphovascular invasion was identified in 6 cases. The tumor invaded the perinephric adipose tissue in 13 cases and was confined to the kidney in only 1 case. Lymph node metastases were identified in all patients who underwent lymph node dissection (5/5). On immunostains, the small cell carcinoma cells were positive for pancytokeratin (11/12), chromogranin (6/9), and synaptophysin (8/9). Follow-up data were available for 13 patients, and 11 died of small cell carcinoma at a mean of 15 months (range, 4-31 months) after diagnosis. Of the 2 surviving patients, 1 was alive at 5 months after diagnosis, and the other, whose disease was confined to the kidney, was alive with no evidence of disease at 137 months. In summary, renal small cell carcinoma is a highly aggressive disease that often presents at an advanced stage with widespread metastases. Patients usually have a poor clinical outcome despite multimodal therapy. The frequent coexistence of small cell carcinoma with urothelial carcinoma suggests that renal small cell carcinomas may evolve from a preexisting urothelial carcinoma.

Prostatic carcinomas with neuroendocrine differentiation diagnosed in needle biopsies, a morphologic study of 7 cases among 465 sequential biopsies in a tertiary cancer center

PURPOSE

Neuroendocrine carcinomas (NEC) of the prostate are rare, with only a few series hitherto reported. The objective of this study was to assess in a single institution the clinical and morphologic characteristics of neuroendocrine carcinomas diagnosed in needle core biopsies.

MATERIALS AND METHODS

The current study analyses seven cases diagnosed in needle biopsies at a large tertiary regional cancer center from Northeastern Brazil. Two pathologists reviewed specimens retrospectively, and demographic and morphologic characteristics were compared to 458 acinar tumors diagnosed in the same period.

RESULTS

There were five small cell carcinomas and two low-grade neuroendocrine carcinomas (carcinoid). NEC were associated with an acinar component in 5/7 cases and the Gleason score of the acinar component was always > 6. The number of cores involved in prostates with NEC was greater (65% compared to 24% of acinar tumors, p < 0.05). The mean PSA at diagnosis was 417.7 (range 5.7-1593, SD 218.3), compared to 100.5 (p = 0.1) of acinar tumors (range 0.3-8545, SD 22.7). Prostates harboring NEC were bigger (p < 0.001, mean volume 240 mL vs. 53 mL of acinar tumors). Treatment of NEC included palliative surgery, chemotherapy, and hormonal therapy.

CONCLUSIONS

NEC of the prostate is rare and often associated with a high-grade acinar component. Prostates with NEC tend to be larger and involve a greater number of cores than acinar tumors. PSA at diagnosis does not seem to predict the presence of NE tumors in needle biopsy.

PC3 is a cell line characteristic of prostatic small cell carcinoma

BACKGROUND

The majority of the prostatic cancers are adenocarcinomas characterized by glandular formation and the expression of luminal differentiation markers androgen receptor (AR) and prostate-specific antigen (PSA). Most adenocarcinomas are indolent and androgen-dependent. Hormonal therapy that inhibits AR signaling produces symptomatic relief in patients with advanced and metastatic adenocarcinomas. Prostatic small cell neuroendocrine carcinoma (SCNC) is a variant form of prostate cancer (PC). In contrast to adenocarcinoma, the tumor cells of SCNC do not form glands and are negative for AR and PSA. SCNC is extremely aggressive and does not respond to hormonal therapy. The purpose of this study was to compare the important and relevant features of two most commonly used PC cell lines, LNCaP and PC3, with prostatic adenocarcinoma and SCNC.

METHODS

Xenograft tumors of LNCaP and PC3 were prepared and compared with human prostatic adenocarcinoma and SCNC for the expression of key signaling molecules by immunohistochemistry and Western blot analysis.

RESULTS

LNCaP cells express AR and PSA and their growth is inhibited by androgen withdrawal, similar to human prostatic adenocarcinoma. PC3 cells do not express AR and PSA and their proliferation is independent of androgen, similar to SCNC. Adenocarcinoma cells and LNCaP cells are negative for neuroendocrine markers and stem cell-associated marker CD44 while SCNC and PC3 cells are positive. LNCaP cells have identical cytokeratin profiles to adenocarcinoma while PC3 cells have cytokeratin profiles similar to SCNC.

CONCLUSION

LNCaP cells share common features with adenocarcinoma while PC3 cells are characteristic of SCNC.

Survival of patients with small cell carcinoma of the prostate during 1973-2003: a population-based study

OBJECTIVE

To describe the survival of patients with primary small cell carcinoma (SCC) of the prostate and assess prognostic factors based on a large population sample.

PATIENTS AND METHODS

A total of 241 cases of SCC of the prostate were reported to the Surveillance, Epidemiology, and End Results (SEER) registries from 1973 to 2003 of which 191 cases were included in our study. We used the Kaplan-Meier method for estimating survival, and Cox proportional hazard regression modelling to evaluate prognostic variables.

RESULTS

The overall age-adjusted incidence rate was 0.278 per 1,000,000 (95% confidence interval, 0.239-0.323). In all, 60.5% presented as metastatic disease compared with 39.5% who presented as local/regional disease (P= 0.012). The 12, 24, 36, 48 and 60 months observed survival rates were 47.9%, 27.5%, 19%, 17% and 14.3% respectively. On univariate analyses, age <60, concomitant low-grade prostatic adenocarcinoma, absence of metastasis, prostatectomy and radiation therapy were favourable prognostic factors. In multivariate regression modelling, age, pathology and stage were strong predictors of survival.

CONCLUSIONS

Using the SEER database, we present the largest study describing the epidemiology of primary SCC of the prostate. We found age, concomitant low-grade prostatic adenocarcinoma, and stage of the disease to be the strongest predictors of survival for patients with prostatic SCC. Future studies evaluating a broader range of clinical and molecular markers are needed to refine the prognostic model of this relatively rare disease.

Review of small cell carcinomas of the prostate

Small cell carcinoma of the prostate is a rare neoplasm, with only a few series hitherto reported. A little less than half of the cases are associated with conventional acinar adenocarcinoma, which are usually high grade. Although consensus has not been reached, the majority of patients with small cell neuroendocrine carcinoma of the prostate have advanced disease at diagnosis and disproportionally low PSA levels compared to patients with conventional acinar adenocarcinoma. Treatment consists mainly of chemotherapy associated with surgery. Radiation therapy is reserved for selected cases. This study reviews the most up-to-date information on small cell carcinomas of the prostate.

Establishment and characterization of a new cell line, A99, from a primary small cell carcinoma of the pancreas

OBJECTIVES

Small cell carcinoma (SCC) of the pancreas is a rare malignancy with a poor prognosis. We established and characterized a primary human pancreatic SCC cell line, designated A99.

METHODS

Cancer tissue was obtained from the liver metastasis of an SCC of the pancreas and xenografted into nude mice. The first-pass xenograft was then used to establish a cultured cell line called A99. Cellular morphology, immunohistochemical properties, tumorigenic potential, and genetic alterations of this new line were characterized.

RESULTS

A99 cells grew consistently in culture, formed colonies in soft agar, and grew as subcutaneous xenografts when inoculated into nude mice. A99 cells were positive for pancytokeratin, synaptophysin, chromogranin A, neuron-specific enolase, CD57 (Leu7), CD56, protein gene product 9.5, thyroid transcription factor 1, Smad4, p53, and p16, but not for CD99, PDX-1, or retinoblastoma protein. Sequencing analysis revealed homozygous point mutations of KRAS and TP53. Cytogenetic analysis revealed complex chromosomal rearrangements including marker chromosomes.

CONCLUSIONS

A99 is the first cell line reported to be derived from a primary SCC of the pancreas. The establishment of this cell line may serve as a useful model system for studying the cell biology of this rare cancer or for evaluating novel targeted agents in preclinical models.

ERG-TMPRSS2 rearrangement is shared by concurrent prostatic adenocarcinoma and prostatic small cell carcinoma and absent in small cell carcinoma of the urinary bladder: evidence supporting monoclonal origin

Prostatic carcinoma is a heterogeneous disease with frequent multifocality and variability in morphology. Particularly, prostatic small cell carcinoma is a rare variant with aggressive behavior. Distinction between small cell carcinoma of the prostate and urinary bladder may be challenging, especially in small biopsy specimens without associated prostatic adenocarcinoma or urothelial carcinoma. Recently, gene fusions between ETS genes, particularly ETS-related gene (ERG), and transmembrane protease, serine 2 (TMPRSS2) have been identified as a frequent event in prostate cancer. Thus, molecular methods may be helpful in determining the primary site of small cell carcinoma. Thirty cases of prostatic small cell carcinoma from the authors' archives were studied, among which 13 had concurrent prostatic adenocarcinoma. Tricolor fluorescence in situ hybridization (FISH) was performed on formalin-fixed paraffin-embedded tissue sections with a probe cocktail for 3'/5' ERG and TMPRSS2. Cases of small cell carcinoma of the bladder and conventional prostatic adenocarcinoma (25 each) were also tested as controls. ERG gene alterations were found only in prostate malignancies and not in benign prostatic tissue or bladder small cell carcinoma. TMPRSS2-ERG gene fusion was found in 47% (14/30) of prostatic small cell carcinoma. Of cases with concurrent prostatic adenocarcinoma, 85% (11/13) had identical findings in both components. In 20% of rearranged cases, the ERG abnormality was associated with 5' ERG deletion. In 17% (5/30) of cases, gain of the 21q22 locus was present. Two cases showed discordant aberrations in the small cell carcinoma and adenocarcinoma, one with deletion of 5' ERG and one with gain of chromosome 21q, both in only the adenocarcinoma component. Small cell carcinoma of the prostate demonstrates TMPRSS2-ERG rearrangement with comparable frequency to prostatic adenocarcinoma. In cases with concurrent adenocarcinoma and small cell carcinoma, the majority showed identical abnormalities in both components, indicating a likely common clonal origin. Discordant alterations were present in rare cases, suggesting that acquisition of additional genetic changes in multifocal tumors may be responsible for disease progression to a more aggressive phenotype. TMPRSS2-ERG fusion is absent in bladder small cell carcinoma, supporting the utility of FISH in distinguishing prostate from bladder primary tumors and identifying metastatic small cell carcinoma of unknown origin.

ERG gene rearrangements are common in prostatic small cell carcinomas

Small cell carcinoma of the prostate is a rare subtype with an aggressive clinical course. Despite the frequent occurrence of ERG gene rearrangements in acinar carcinoma, the incidence of these rearrangements in prostatic small cell carcinoma is unclear. In addition, molecular markers to distinguish prostatic small cell carcinomas from lung and bladder small cell carcinomas may be clinically useful. We examined the occurrence of ERG gene rearrangements by fluorescence in situ hybridization in prostatic, bladder and lung small cell carcinomas. We also examined the expression of ERG, androgen receptor (AR) and NKX3-1 by immunohistochemistry in prostatic cases. Overall, 45% (10/22) of prostatic small cell carcinoma cases harbored ERG rearrangements, whereas no cases of bladder or lung small cell carcinomas showed ERG rearrangement (0/12 and 0/13, respectively). Of prostatic small cell carcinoma cases, 80% (8/10) showed ERG deletion and 20% (2/10) showed ERG translocation. In 83% (5/6) of prostatic small cell carcinoma cases in which a concurrent conventional prostatic acinar carcinoma component was available for analysis, there was concordance for the presence/absence of ERG gene rearrangement between the different subtypes. ERG, AR and NKX3-1 protein expression was detected in a minority of prostatic small cell carcinoma cases (23, 27 and 18%, respectively), while these markers were positive in the majority of concurrent acinar carcinoma cases (66, 83 and 83%, respectively). The presence of ERG rearrangements in nearly half of the prostatic small cell carcinomas is a similar rate of rearrangement to that found in prostatic acinar carcinomas. Furthermore, the high concordance rate of ERG rearrangement between the small cell and acinar components in a given patient supports a common origin for these two subtypes of prostate cancer. Finally, the absence of ERG rearrangement in bladder or lung small cell carcinomas highlights the utility of detecting ERG rearrangement in small cell carcinomas of unknown primary for establishing prostatic origin.

Premalignant and malignant prostate lesions: pathologic review

BACKGROUND

High-grade prostatic intraepithelial neoplasia (HGPIN) is currently the only recognized premalignant lesion of prostatic carcinoma.

METHODS

This review article discusses HGPIN, its link to prostatic adenocarcinoma, and the significance of its presence on needle biopsy. The criteria and clinical impact of the diagnosis of atypical small acinar proliferation on needle biopsy are reviewed. Certain subtypes of prostate cancer that are not associated with HGPIN are of clinical relevance, and the unique clinicopathologic features of these subtypes are discussed. Histologic variants of prostatic adenocarcinoma with distinct cell types are also described.

RESULTS

HGPIN is the only known pathologic factor currently available to distinguish which patients may be at risk for detecting carcinoma on repeat biopsy. Histologic variants are recognized due to the inference of a particular Gleason grade pattern associated with the cell type, hence affecting prognosis. Typically, pure forms of these histologic variants are associated with worse prognosis due to the associated high Gleason grades.

CONCLUSIONS

HGPIN has a strong association with acinar-type prostatic adenocarcinoma. HGPIN and acinar-type prostatic adenocarcinoma both show similar molecular alterations, providing further evidence of their association.

A case of robot-assisted laparoscopic radical prostatectomy in primary small cell prostate cancer

Primary small cell carcinoma of the prostate is a rare and very aggressive disease with a poor prognosis, even in its localized form. We managed a case of primary small cell carcinoma of the prostate. The patient was treated with robot-assisted laparoscopic radical prostatectomy and adjuvant chemotherapy. Herein we report this first case of robot-assisted laparoscopic radical prostatectomy performed in a patient with primary small cell carcinoma of the prostate.

Wnt/β-catenin activation promotes prostate tumor progression in a mouse model

Our previous studies have found that activation of Wnt/β-Catenin signaling resulted in mouse prostatic intraepithelial neoplasia (mPIN). In the large probasin promoter directed SV40-Large T-antigen (LPB-Tag) expressing mouse prostate, mPIN forms with rare areas of adenocarcinoma. Combining expression of both Wnt-signaling and Tag expression in the mouse prostate, we have studied the role of Wnt/β-Catenin signaling in the progression from mPIN to adenocarcinoma. Our results show that the prostates of mice expressing Tag alone or nuclear β-Catenin alone developed mPIN while the activation of both Tag and the Wnt/β-Catenin pathway resulted in invasive prostate adenocarcinoma. Also, Foxa2, a forkhead transcription factor, was induced by active Wnt/β-Catenin signaling; and the expression of Foxa2 was associated with the invasive phenotype in the primary prostate cancer. In the LPB-Tag/dominant active (D.A.) β-Catenin prostates, MMP7, a Wnt/β-Catenin target gene, was up-regulated. Furthermore, we also assessed AR and AR signaling pathway in these LPB-Tag/D.A. β-Catenin mice. Although β-Catenin is a well known AR co-activator in vitro, our study provides strong in vivo evidences indicating that both AR protein and the AR pathway were down-regulated in the prostate of LPB-Tag/D.A. β-Catenin mice. Histological analysis shows that prostate sections derived from the LPB-Tag/D.A. β-Catenin mice display neuroendocrine differentiation (NED) but NE cancer does not develop. Together, our findings indicate that Wnt/β-Catenin signaling plays an important role in the progression of mPIN to prostate adenocarcinoma.

TMPRSS2-ERG gene fusion in small cell carcinoma of the prostate

Recent studies have shown that most prostate cancers carry the TMPRSS2-ERG gene fusion. Here we evaluated the TMPRSS2-ERG gene fusion in small cell carcinoma of the prostate (n = 12) in comparison with small cell carcinoma of the urinary bladder (n = 12) and lung (n = 11). Fluorescence in situ hybridization demonstrated rearrangement of the ERG gene in 8 cases of prostatic small cell carcinoma (67%), and the rearrangement was associated with deletion of the 5' ERG gene in 7 cases, but rearrangement of the ERG gene was not present in any small cell carcinoma of the urinary bladder or lung. Next we evaluated the TMPRSS2-ERG gene fusion in nude mouse xenografts that were derived from 2 prostatic small cell carcinomas carrying the TMPRSS2-ERG gene fusion. Two transcripts encoded by the TMPRSS2-ERG gene fusion were detected by reverse transcriptase polymerase chain reaction, and DNA sequencing demonstrated that the 2 transcripts were composed of fusions of exon 1 of the TMPRSS2 gene to exon 4 or 5 of the ERG gene. Our study demonstrates the specific presence of TMPRSS2-ERG gene fusion in prostatic small cell carcinoma, which may be helpful in distinguishing small cell carcinoma of prostatic origin from nonprostatic origins. The high prevalence of the TMPRSS2-ERG gene fusion in prostatic small cell carcinoma as well as adenocarcinoma implies that small cell carcinoma may share a common pathogenic pathway with adenocarcinoma in the prostate.

ERG rearrangement in small cell prostatic and lung cancer

AIMS

Small cell prostatic cancer is a rare but aggressive disease. Currently, its histogenetic origin is unclear and its distinction from metastatic small cell lung cancer is challenging. The aim of our study was to determine whether the ERG rearrangement commonly observed in acinar prostatic cancer can distinguish small cell prostatic cancer from small cell lung cancer samples.

METHODS AND RESULTS

We assessed 15 small cell prostatic cancers and 22 small cell lung cancers for ERG rearrangement using fluorescence in situ hybridization. Commonly used and novel immunohistochemical markers (i.e. androgen receptor, calcium activated nucleotidase 1, Golgi phosphoprotein 2, prostate-specific antigen, prostate-specific membrane antigen, CD56, epithelial membrane antigen, thyroid transcription factor 1, chromogranin A, synaptophysin and Ki67) were further studied. ERG rearrangement occurred in 86% of small cell prostatic cancers but in none of the small cell lung cancers and was the best marker to differentiate between both tumours (P < 0.0001).

CONCLUSIONS

The ERG rearrangement is commonly observed in small cell prostatic cancer, supporting the hypothesis that ERG rearrangement occurs in aggressive prostatic cancers. Furthermore, the ERG rearrangement is the most significant marker to differentiate between small cell prostatic cancer and small cell lung cancer. Moreover, our data suggest that small cell prostatic cancer is not a tumour entity on its own, but a dedifferentiated variant of common acinar prostatic cancer.

TTF1 expression in normal lung neuroendocrine cells and related tumors: immunohistochemical study comparing two different monoclonal antibodies

Thyroid transcription factor-1 (TTF1) regulates lung morphogenesis and differentiation, and its immunohistochemical expression is used for identifying lung neoplasms. The 8G7G3/1 antibody has been used in previous studies, but a different and more sensitive anti-TTF1 antibody, named SPT24, has become commercially available. Since the immunohistochemical expression of TTF1 in normal lung neuroendocrine (NE) cells has not been previously investigated and its utility in the diagnosis of lung NE tumors is a controversial issue, we studied the TTF1 expression in normal adult and fetal lungs, in 83 pulmonary NE neoplasms, in 131 non-lung NE tumors and in 36 metastases from these neoplasms using these two antibodies. A TTF1 immunoreactivity was demonstrated in normal fetal and adult NE cells when using the SPT24 clone. Conversely, using the 8G7G3/1 antibody, only rare fetal neuroendocrine cells were TTF1 positive while adult NE cells were negative. The SPT24 clone identified TTF1 expression in more carcinoids, most of them peripherally located, and poorly differentiated NE carcinomas than the 8G7G3/1 clone. Non-pulmonary well-differentiated NE tumors were negative for both antibodies. Among the 45 non-pulmonary poorly differentiated NE carcinomas 11% were positive for 8G7G3/1 and 18% for SPT24. TTF1 expression in metastases perfectly reflected that detected in the related primary tumors. Our results indicate that the SPT24 antibody is more sensitive than the 8G7G3/1 clone for labeling lung carcinoids and it appears particularly useful in detecting peripheral neoplasms. In addition, the expression of TTF1 in normal NE cells suggests a possible role for the transcription factor in their development and differentiation.

Pathology reporting of neuroendocrine tumors: application of the Delphic consensus process to the development of a minimum pathology data set

Epithelial neuroendocrine tumors (NETs) have been the subject of much debate regarding their optimal classification. Although multiple systems of nomenclature, grading, and staging have been proposed, none has achieved universal acceptance. To help define the underlying common features of these classification systems and to identify the minimal pathology data that should be reported to ensure consistent clinical management and reproducibility of data from therapeutic trials, a multidisciplinary team of physicians interested in NETs was assembled. At a group meeting, the participants discussed a series of "yes" or "no" questions related to the pathology of NETs and the minimal data to be included in the reports. After discussion, anonymous votes were taken, using the Delphic principle that 80% agreement on a vote of either yes or no would define a consensus. Questions that failed to achieve a consensus were rephrased once or twice and discussed, and additional votes were taken. Of 108 questions, 91 were answerable either yes or no by more than 80% of the participants. There was agreement about the importance of proliferation rate for tumor grading, the landmarks to use for staging, the prognostic factors assessable by routine histology that should be reported, the potential for tumors to progress biologically with metastasis, and the current status of advanced immunohistochemical and molecular testing for treatment-related biomarkers. The lack of utility of a variety of immunohistochemical stains and pathologic findings was also agreed upon. A consensus could not be reached for the remaining 17 questions, which included both minor points related to extent of disease assessment and some major areas such as terminology, routine immunohistochemical staining for general neuroendocrine markers, use of Ki67 staining to assess proliferation, and the relationship of tumor grade to degree of differentiation. On the basis of the results of the Delphic voting, a minimum pathology data set was developed. Although there remains disagreement among experts about the specific classification system that should be used, there is agreement about the fundamental pathology data that should be reported. Examination of the areas of disagreement reveals significant opportunities for collaborative study to resolve unanswered questions.

Dramatically elevated circulating tumor cell numbers in a patient with small cell neuroendocrine carcinoma of the prostate

Detection of circulating tumor cells in whole blood is a useful prognostic tool for patients with castration-resistant prostate cancer, as well as for patients with metastatic breast cancer and colorectal carcinoma. In this report, we present the case of a patient with neuroendocrine small cell prostate cancer with normal prostate-specific antigen levels throughout the course of disease but who had markedly elevated circulating tumor cells, as detected with the CellSearch (Veridex) system.

The relationship of neuroendocrine carcinomas to anti-tumor therapies in TRAMP mice

BACKGROUND

Neuroendocrine differentiation and neuroendocrine carcinoma (NEC) have been linked to androgen deprivation in prostate cancers. No previous study has directly connected neuroendocrine phenotypes to chemotherapy. The pathogenesis of prostatic NEC has not yet been determined.

METHODS

Using the transgenic adenocarcinoma of mouse prostate (TRAMP) model, we studied tumor progression after hormone ablation (castration) and/or chemotherapy (docetaxel), and analyzed the incidence of NEC as a function of the anti-tumor therapies. Non-treated mice were used as controls. Protein expressions in tumor tissues were analyzed by Western blots and immunohistochemistry.

RESULTS

Although all animals developed prostate cancer, no NEC was found in control mice. However, over 30% of the mice that received an anti-tumor therapy developed NEC. A similar incidence of NEC was found in the castration-only and docetaxel-only treatment groups, while a higher incidence was observed in the combined treatment (castration and docetaxel) group. The NEC-bearing mice had smaller tumors in their prostates and lived longer than mice with adenocarcinoma (ADC-only). However, NEC tumors had a higher proliferative index and greater potential for metastasis and drug-resistance, as evidenced by significantly higher expression levels of PCNA, S100A4, and Pgp, but lower levels of E-cadherin. SV40 T-antigen was highly expressed in both NEC and ADC tumors.

CONCLUSIONS

Stress induced by anti-cancer treatments may play a role in NEC development. Although NEC and ADC differ in their expressions of many proteins, a high level of SV40 T-antigen in both tumor types suggest a common progenitor..

Histological variants of urothelial carcinoma: diagnostic, therapeutic and prognostic implications

It is well established that invasive urothelial carcinoma, involving the urinary bladder and renal pelvis, has marked propensity for divergent differentiation. In recent years, several 'variant' morphologies have been described and most have been recognized in the 2004 World Health Organization Classification. These histological variants of urothelial carcinoma have clinical significance at various levels, including diagnostic, that is, awareness of the morphological variant is essential in order to avoid diagnostic misinterpretations; prognostic for patient risk stratification; and therapeutic, where a diagnostic assignment of a particular variant may be associated with the administration of a therapy distinctive from that used in conventional invasive urothelial carcinoma. The diagnoses of micropapillary urothelial carcinoma, small-cell carcinoma, lymphoepithelioma-like carcinoma and sarcomatoid carcinoma are prime examples where treatment protocols may be different than the usual muscle-invasive bladder cancer. This review discusses the variants of urothelial carcinoma, outlining for each the diagnostic features, differential diagnostic considerations and the clinical significance.

Neuroendocrine tumours of the urinary system and male genital organs: clinical significance

Two basic types of neuroendocrine (NE) tumours with diverse clinicopathological features and outcome are identified in the urinary system and male genital organs: carcinoid tumour and neuroendocrine carcinoma. Carcinoid, a rare tumour, occurs in the kidney, bladder, prostate and testis. It is morphologically, histochemically, immunohistochemically and ultrastructurally similar to its counterpart in other organs, such as lung or gastrointestinal tract. Metastases can be detected at the initial evaluation, although they have been reported up to several years after removal, emphasizing the need for a long-term follow-up. NE carcinoma occurs in the kidney, bladder and prostate, and includes small cell carcinoma (SCC) and large cell NE carcinoma (LCNEC), the latter being exceedingly rare. Both show the morphology and immunophenotype of NE carcinoma originating in other organs. Although the occurrence is rare, it is highly aggressive.

Small cell lung cancer: significance of RB alterations and TTF-1 expression in its carcinogenesis, phenotype, and biology

Small cell lung cancer (SCLC) exhibits highly aggressive behavior and has a poor prognosis. While numerous investigations have been carried out, the exact mechanism of its carcinogenesis and aggressiveness is still unclear. SCLC is categorized as a neuroendocrine neoplasia and has a genetic profile characterized by universal alterations of the RB and TP53 genes. Epidemiological studies indicate the majority of SCLCs to be caused by smoking and the TP53 mutational pattern to be consistent with that evoked by smoke carcinogens; however, there is no direct evidence that such carcinogens induce alterations to RB in SCLC. While the importance of these alterations in the carcinogenesis of SCLC is strongly suggested, the exact molecular mechanism has been only little elucidated. SCLC cells almost always express mammalian achaete-scute homolog-1 (MASH1) and thyroid transcription factor-1 (TTF-1). MASH1 plays a critical role in neuroendocrine differentiation. TTF-1 is a characteristic marker of distal airway cells and pulmonary adenocarcinomas, but is also expressed in extrapulmonary neuroendocrine cancers. Thus, TTF-1 may well play a significant role in the development of neuroendocrine cancers. Recent studies indicate that the airway stem cell is committed to the neuroendocrine lineage through MASH1 and Notch signaling and that only RB-deleted neuroendocrine cells selectively proliferate in response to E2F3, eventually undergoing transformation to neuroendocrine cancer cells, probably in concert with TP53 gene aberrations. Thus, alterations of both the RB and TP53 genes are central to the carcinogenesis of SCLC, while many other factors including MASH1 and TTF-1 contribute to the development and biological behavior of SCLC.

CD44 expression is a feature of prostatic small cell carcinoma and distinguishes it from its mimickers

Small cell neuroendocrine carcinoma of the prostate is a rare variant of prostatic cancer that shares morphologic similarity with prostatic adenocarcinoma of Gleason 5 pattern. It has also been considered morphologically and immunohistochemically indistinguishable from small cell neuroendocrine carcinomas of other origins. CD44 is a cell-surface molecule proposed to identify cancer stem/progenitor cells in prostate cancer. We performed immunohistochemical study for CD44 expression in 11 cases of prostatic small cell neuroendocrine carcinoma and compared its patterns of expression with 73 cases of prostatic adenocarcinoma and 47 cases of small cell neuroendocrine carcinomas of other organs. Strong and diffuse membrane staining for CD44 was observed in 100% of the prostatic small cell neuroendocrine carcinomas. In conventional adenocarcinomas of the prostate, positive staining was only seen in rare, scattered tumor cells; and CD44 staining was negative in most of the small cell neuroendocrine carcinomas of nonprostate origin. The difference in CD44 expression between small cell neuroendocrine carcinomas of the prostate and those of other organs are statistically significant (P < .001). Our study demonstrates the utility of immunohistochemical staining for CD44 in distinguishing prostatic small cell neuroendocrine carcinoma from its mimickers including prostatic adenocarcinoma of Gleason 5 pattern and small cell neuroendocrine carcinomas of other organs. CD44 is the first marker that shows a high degree of tissue/organ specificity for small cell neuroendocrine carcinomas. Because CD44 is a putative marker of prostate cancer stem cells, the strong and diffuse expression of CD44 and the lack of expression of prostate luminal differentiation markers androgen receptor and prostatic specific antigen in prostatic small cell neuroendocrine carcinomas suggest that the tumor cells may retain cancer stem cell features.

Rare and unusual histological variants of prostatic carcinoma: clinical significance

We review the clinicopathological features of the following unusual histological variants of prostatic carcinoma: small cell carcinoma, ductal adenocarcinoma, sarcomatoid (carcinosarcoma), basal cell, squamous cell and adenosquamous, and urothelial carcinoma. These variants are rare and account for 5-10% of carcinomas that originate in the prostate. Some develop from acinar adenocarcinoma after hormonal or radiation therapy. They are usually aggressive tumours that often present with secondary deposits. The outcome is generally poor. Only basal cell carcinoma is seen as a low-grade carcinoma.

The nuclear factor-kappaB pathway controls the progression of prostate cancer to androgen-independent growth

Typically, the initial response of a prostate cancer patient to androgen ablation therapy is regression of the disease. However, the tumor will progress to an "androgen-independent" stage that results in renewed growth and spread of the cancer. Both nuclear factor-kappaB (NF-kappaB) expression and neuroendocrine differentiation predict poor prognosis, but their precise contribution to prostate cancer progression is unknown. This report shows that secretory proteins from neuroendocrine cells will activate the NF-kappaB pathway in LNCaP cells, resulting in increased levels of active androgen receptor (AR). By blocking NF-kappaB signaling in vitro, AR activation is inhibited. In addition, the continuous activation of NF-kappaB signaling in vivo by the absence of the IkappaBalpha inhibitor prevents regression of the prostate after castration by sustaining high levels of nuclear AR and maintaining differentiated function and continued proliferation of the epithelium. Furthermore, the NF-kappaB pathway was activated in the ARR(2)PB-myc-PAI (Hi-myc) mouse prostate by cross-breeding into a IkappaBalpha(+/-) haploid insufficient line. After castration, the mouse prostate cancer continued to proliferate. These results indicate that activation of NF-kappaB is sufficient to maintain androgen-independent growth of prostate and prostate cancer by regulating AR action. Thus, the NF-kappaB pathway may be a potential target for therapy against androgen-independent prostate cancer.