Small cell undifferentiated ('neuroendocrine') carcinoma of the colon

Small-cell neuroendocrine carcinoma of the rectum - a rare tumor type with poor prognosis: A case report and review of literature

BACKGROUND

Small-cell neuroendocrine carcinoma (SNEC) of the rectum is a rare tumor associated with poor prognosis.

CASE SUMMARY

We report a case of a 77-year-old male who came into our hospital because of blood with his stool. An endoscopy revealed a cauliflower-like neoplasm in his rectum. Imaging examination showed that the lesion in the upper rectum was likely rectal cancer, and there was no evidence of metastasis. The patient was treated with surgery. Pathological examination confirmed SNEC of the rectum and an R0 resection was achieved. However, 1 mo after the operation, the patient developed intestinal and ureteral obstructions due to peritoneal metastases. Finally, the patient died from renal failure.

CONCLUSION

SNEC of the rectum is a high-grade carcinoma with an aggressive phenotype, and surgery should be cautiously considered.

Small cell carcinoma of the stomach: A report of two cases and a review of the literature

Primary small cell gastric carcinomas (SCGC) are rare tumors with an aggressive nature, characterized by early, widespread metastases and poor overall prognosis. SCGC shares similar clinicopathological and molecular characteristics with small cell lung carcinoma and is usually treated in a similar manner. Here, two cases of SCGC in young Caucasian male patients are presented. One patient had metastatic and the other locoregional disease. Multimodal treatment was applied in each case; the resulting survival time was 20.2 months in the patient with initially locoregional disease whereas the remains alive and disease-free 20 months after initial diagnosis. A review of the literature is also presented.

Radiation therapy improves survival in rectal small cell cancer - Analysis of Surveillance Epidemiology and End Results (SEER) data

Background

Small cell carcinoma of the rectum is a rare neoplasm with scant literature to guide treatment. We used the Surveillance Epidemiology and End Results (SEER) database to investigate the role of radiation therapy in the treatment of this cancer.

Methods

The SEER database (National Cancer Institute) was queried for locoregional cases of small cell rectal cancer. Years of diagnosis were limited to 1988–2010 (most recent available) to reduce variability in staging criteria or longitudinal changes in surgery and radiation techniques. Two month conditional survival was applied to minimize bias by excluding patients who did not survive long enough to receive cancer-directed therapy. Patient demographics between the RT and No_RT groups were compared using Pearson Chi-Square tests. Overall survival was compared between patients who received radiotherapy (RT, n = 43) and those who did not (No_RT, n = 28) using the Kaplan-Meier method. Multivariate Cox proportional hazards model was used to evaluate important covariates.

Results

Median survival was significantly longer for patients who received radiation compared to those who were not treated with radiation; 26 mo vs. 8 mo, respectively (log-rank P = 0.009). We also noted a higher 1-year overall survival rate for those who received radiation (71.1% vs. 37.8%). Unadjusted hazard ratio for death (HR) was 0.495 with the use of radiation (95% CI 0.286-0.858). Among surgery, radiotherapy, sex and age at diagnosis, radiation therapy was the only significant factor for overall survival with a multivariate HR for death of 0.393 (95% CI 0.206-0.750, P = 0.005).

Conclusions

Using SEER data, we have identified a significant survival advantage with the use of radiation therapy in the setting of rectal small cell carcinoma. Limitations of the SEER data apply to this study, particularly the lack of information on chemotherapy usage. Our findings strongly support the use of radiation therapy for patients with locoregional small cell rectal cancer.

Synchronous Small Cell Neuroendocrine Carcinoma and Adenocarcinoma of the Colon: A Link for Common Stem Cell Origin?

Synchronous carcinomas have been recognized for over a century, with synchronous primary adenocarcinoma of the colon reported to range from 2-11% of cases involving this type of malignancy. Small cell carcinomas occur frequently with colorectal adenomas; however, despite these reports and a known adenoma-to-carcinoma sequence, scarce literature exists on synchronous colorectal adenocarcinoma and small cell carcinomas. We present a rare cancer of synchronous small cell neuroendocrine carcinomas and discuss a possible link between these two cancers.

Colorectal neuroendocrine carcinomas and adenocarcinomas share oncogenic pathways. A clinico-pathologic study of 12 cases

OBJECTIVE

Neuroendocrine carcinomas (NECs) are rare neoplasms with an increasing incidence. Oncogenetic pathways of colorectal NEC are still poorly understood, and no treatment standards are available for these rare tumors.

METHODS

We analyzed retrospectively the clinical records and histology of 12 patients with colorectal NEC. KRAS and BRAF mutations were investigated after the dissection of exoendocrine and neuroendocrine components. ALK alterations and EML4-ALK transcripts were detected by in-situ hybridization and determination of fusion transcripts, respectively.

RESULTS

At the time of diagnosis, the mean age of the patients was 60 years (40-79) and 10 patients had synchronous metastases. A transient response occurred in two patients and one patient treated with cisplatin-etoposide or fluoropyrimidine-oxaliplatin, respectively. Tumor progression-related death occurred in 11 of 12 patients. Ten tumors contained an exocrine component, accounting for 5-70% of the tumor, and the other two contained an amphicrine component. BRAF/KRAS mutations were found in six of 10 tumors, corresponding to BRAF(V600E) (n=2) or KRAS(G12D) (n=2), KRAS(G12V) or KRAS(G13D). DNA was obtained from both exocrine and endocrine components in seven cases, and the BRAF/KRAS status was identical in all cases. Split of the ALK locus was detected in a minority of tumor cells in two of eight cases, but EML4-ALK transcripts were absent.

CONCLUSION

The association of an exocrine component in all cases and the similar profile of BRAF/KRAS mutations indicate that colorectal NEC may correspond to a high-grade transformation of colorectal carcinoma. New chemotherapy regimens using targeted therapies should be assessed in these tumors.

Mixed Adenoneuroendocrine Carcinomas (MANECs) of the Gastrointestinal Tract: An Update

The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.

The immune response to sporadic colorectal cancer in a novel mouse model

Current mouse models do not reflect the sporadic nature of colon cancer and do not allow the analysis of antitumor immune response because of the lack of known tumor-specific antigens. Two transgenic mouse models with spontaneous tumor development were generated, directing the expression of SV40T antigen (Tag) either constitutively (Vil-Cre × LoxP-Tag-transgenic mice) or stochastically (Vil-Cre-ER(T2) × LoxP-Tag-transgenic mice) into the putative stem cell region of the crypt of Lieberkühn. Tumor development and antitumor immune response were monitored. Vil-Cre × LoxP-Tag mice developed multiple adenocarcinomas of the small intestine and colon at an average age of 6 months. During the tumor development, Tag-specific immunoglobulin G (IgG) antibodies were induced in half of the mice, although they had developed neonatal cytotoxic T lymphocyte (CTL) tolerance. This model shows similarity to hereditary colon cancer but not to the sporadic tumor development. Therefore, the conditional Vil-Cre-ER(T2) × LoxP-Tag mice were established, in which expression of the dormant Tag was induced by stochastic, tissue-specific activation of Cre recombinase. These mice spontaneously developed highly invasive, metastasizing colon carcinomas at an average age of 20 months. Colon carcinomas expressed epithelial and/or neuroendocrine markers depending on the grade of differentiation. Young Vil-Cre-ER(T2) × LoxP-Tag mice had retained CTL responses against epitope IV of Tag. The tumors induced strong anti-Tag IgG responses. We report, for the first time, a mouse model based on stochastic, tissue-specific activation of a dormant oncogene in the colon allowing the analysis of antitumor immune response against primary colorectal cancer.

Cisplatin and etoposide as first-line chemotherapy for poorly differentiated neuroendocrine carcinoma of the hepatobiliary tract and pancreas

OBJECTIVE

The combination chemotherapy consisting of cisplatin and etoposide, one of the standard regimens for small cell lung cancer, has been widely used to treat extrapulmonary poorly differentiated neuroendocrine carcinomas. However, there were no prior reports limited to the hepatobiliary tract and pancreas as the primary sites.

METHODS

We reviewed the cases in our database from October 1995 to January 2009 and retrospectively examined the clinical data of patients, with unresectable or recurrent poorly differentiated neuroendocrine carcinoma arising from the hepatobiliary tract and pancreas, who received combination chemotherapy with cisplatin and etoposide as the first-line treatment. The chemotherapy regimen consisted of cisplatin 80 mg/m(2) given intravenously on day 1 and etoposide 100 mg/m(2) intravenously on days 1-3, repeated every 3-4 weeks.

RESULTS

Twenty-one patients were treated with the above regimen of cisplatin and etoposide combination chemotherapy. The primary tumor site was the liver in 2 patients, gallbladder in 8 patients, pancreas in 10 patients and ampulla of Vater in 1 patient. Although no complete responses were obtained, three patients had partial responses, resulting in an overall response rate of 14%. Median progression-free survival was 1.8 months, and median overall survival was 5.8 months. The major adverse events were myelosuppression and gastrointestinal toxicities, with Grade 3 or 4 neutropenia (90%), nausea (33%) and anorexia (24%).

CONCLUSIONS

Cisplatin and etoposide combination as the first-line chemotherapy for hepatobiliary or pancreatic poorly differentiated neuroendocrine carcinoma had only marginal antitumor activity and relatively severe toxicity compared with previous studies on extrapulmonary poorly differentiated neuroendocrine carcinoma treated with the same regimen.

Small cell carcinomas of the gastrointestinal tract: clinicopathological features and treatment approach

Small cell undifferentiated carcinoma (SmCC) of the gastrointestinal tract (GIT) is a rare and highly aggressive malignancy. To date, fewer than 1,000 cases have been reported, with an estimated prevalence of 0.1% to 1% of all gastrointestinal (GI) tumors. Data on the disease are scarce due to its rarity and the fact that most authors have focused on one site within the GIT. In light of the limited data and its perceived similarity to SmCC of the lung, the disease has usually been treated as the latter. Nevertheless, recent clinicopathologic and molecular data imply several differences between the two entities, questioning the extent to which extrapolations from one to the other can be made. We review the available data on GI SmCC with emphasis on outlining its clinicopathologic features and the recommended treatment approach.

The mismatch repair protein status of colorectal small cell neuroendocrine carcinomas

Small cell neuroendocrine carcinoma (SCNC) of the colorectum is a rare and highly aggressive malignancy. It can be associated with conventional-type adenocarcinoma, and an overlying adenoma can often be identified. A disproportionate number has been noted to arise in the right colon. Although some phenotypes (eg, mucinous adenocarcinoma) have been shown to be associated with deficient mismatch repair (MMR) and thus microsatellite instability (MSI), the MMR protein status of colorectal SCNCs has not been investigated. This study investigated the status of 3 MMR proteins, hMLH1, hMSH2, and hMSH6, in SCNCs of the colorectum. Fifteen SCNCs were identified on the basis of previous descriptions and the World Health Organization histologic criteria for the diagnosis of pulmonary small cell carcinoma and immunohistochemical evidence of epithelial and neuroendocrine differentiation. Patient age and sex and tumor size and location were recorded. Immunohistochemistry was performed with antibodies to pancytokeratin (cocktail), CD56, neuron specific enolase, synaptophysin, chromogranin, hMLH1, hMSH2, and hMSH6. Patients' ages ranged from 44 to 87 years (mean age = 73 y) and there were 9 men and 6 women. Tumors were located in the right colon (6), sigmoid colon (4), and rectum (3) (the locations of 2 cases were not recorded) and ranged in size from 0.4 to 15 cm in greatest dimension (mean = 6.6 cm). All tumors showed immunoreactivity with antibodies to pancytokeratin and with antibodies to at least 1 neuroendocrine antigen. MMR proteins were intact by immunohistochemistry in all but a single case that had neither an identifiable precursor lesion nor positive internal control (hMLH1 loss). Colorectal SCNCs are rare and are often right-sided. They are aggressive and tend to occur in older individuals. Most colorectal SCNCs have intact MMR proteins, suggesting that they develop secondary to chromosomal instability rather than MSI. Our single case showing potential MMR protein loss suggests that this phenotype may be independent of the developmental pathway (ie, chromosomal instability vs. MSI). This may explain the rare cases of SCNC that have been identified in patients with hereditary nonpolyposis colon cancer.

Primary small cell carcinoma of the cecum

Cecal extrapulmonary small cell carcinoma (cESC) is extremely rare, with only single previous report of occurrence in a child. We report a 76-year-old man admitted for evaluation of a cecal mass seen in colonoscopy. Histology revealed small cell carcinoma with classic immunohistochemical profile similar to those seen in the colon. Further clinical survey documented absence of any other masses or abnormality. To the best of our knowledge, this is the first case of primary cESC occurring in an adult. Awareness of the pathologist and clinician of the cecum as a potential site of cESC may help to prevent misdiagnosis as poorly differentiated adenocarcinoma. This is crucial because extrapulmonary small cell carcinomas usually have worse prognosis.

Small cell carcinoma of rectum: A case report

We present a case of a 40-year-old woman with small-cell carcinoma (SCC) of the rectum. She had profuse bleeding in rectum for 5 d. By colonoscopy, polyps were determined in the rectum and biopsies were carried out. Histopathologically, the polyps were adenomatous. Because of the profuse bleeding in rectum, she underwent low anterior resection. After the diagnosis of SCC, she received intravenous chemotherapy with standard doses of siklofosfamid, adriamycin, and vepesid. Nevertheless, intracranial metastases were revealed and she died 6 mo after the operation.

Hepatocellular carcinoma with an unusual neuroendocrine component

We report a rare case of hepatocellular carcinoma (HCC) with an unusual neuroendocrine component. During a follow-up study for chronic hepatitis C in a 71-year-old man, a nodular lesion showed rapid growth from 1 cm to 4 cm in diameter within 3 months. Histologically, the tumor was consistent with moderately differentiated HCC, but was intermingled with nests of small round cells with scarce cytoplasm, which resembled those found in small cell carcinoma. This population formed small solid nests among the trabecular structures. Immunohistochemically the small round cell component of the tumor was strongly positive for neuron-specific enolase (NSE), chromogranin A and synaptophysin, but hepatocyte paraffin-1 (HP-1) and alpha-fetoprotein (AFP) were negative. In contrast, HP-1 and AFP were positive, and NSE, chromogranin A and synaptophysin were negative in moderately differentiated HCC tissues. Electron microscopy revealed many intracytoplasmic neurosecretory granules in the small round cells. The labeling indexes of p53 and Ki-67 were significantly higher in the small round cell component than in the moderately differentiated HCC component. Overall, we conclude that this nodule was HCC with neuroendocrine differentiation.

Aberrant Expression of Human Achaete-Scute Homologue Gene 1 in the Gastrointestinal Neuroendocrine Carcinomas

Purpose: Gastrointestinal neuroendocrine carcinoma (NEC) is extremely aggressive, but its pathophysiologic features remain poorly understood. There have been no biologically specific markers for this disease. In this study, distinctive up-regulation of human achaete-scute homologue 1 (hASH1) in gastrointestinal NECs was clarified.

Experimental Design: Expression of hASH1 in NECs (n=10), carcinoid tumors (n = 10), other tumors (10adenocarcinomas, 2 squamous cell carcinomas and 1 malignant lymphoma), and the corresponding normal mucosa were investigated by in situ hybridization, reverse transcription-PCR (RT-PCR), real-time RT-PCR, and immunohistochemistry.

Results: By in situ hybridization, mild to intense signals of hASH1 mRNA were detected in 9 of 10 NECs, but not in other tumors or normal mucosa, except for focally weak signals in one carcinoid tumor. RT-PCR showed strong expression of hASH1 in a small cell NEC, followed by a moderately differentiated NEC, and a carcinoid tumor, whereas it is undetectable in adenocarcinomas or normal mucosa. By real-time RT-PCR, the amounts of hASH1 mRNA in a small cell NEC were 16,600 times higher than those in adenocarcinomas and 110 times higher than those in a carcinoid tumor. Immunohistochemically, mammalian homologue of hASH1 was positive in 7 of 10 NECs but was negative in the other tumors. Pan-endocrine markers chromogranin A and synaptophysin were positive in almost all carcinoid tumors, in 4 and 7 of the 10 NECs, respectively.

Conclusions: These findings revealed that hASH1 is distinctly up-regulated in gastrointestinal NECs. hASH1 may be used as a more sensitive and specific marker than conventional pan-endocrine markers for clinical diagnosis of gastrointestinal NECs.

Mice Expressing SV40 T Antigen Directed by the Intestinal Trefoil Factor Promoter Develop Tumors Resembling Human Small Cell Carcinoma of the Colon

The colonic epithelium contains three major types of mature cells, namely, absorptive, goblet, and enteroendocrine cells. These cells are maintained by a complex process of cell renewal involving progenitor and stem cells, and colon cancers develop when this process goes awry. Much is known about the genetic and epigenetic changes that occur in cancer; however, little is known as to the specific cell types involved in carcinogenesis. In this study, we expressed the SV40 Tag oncogene in the intestinal epithelium under the control of an intestinal trefoil factor (ITF) promoter. This caused tumor formation in the proximal colon with remarkable efficiency. ITFTag tumors were rapidly growing, multifocal, and invasive. ITFTag tumor cells express synaptophysin and contain dense core secretory granules, markers of neuroendocrine differentiation. The cell type involved in the early steps of ITFTag tumorigenesis was studied by examining partially transformed crypts that contained populations of both normal and dysplastic cells. The dysplastic cell population always expressed both Tag and synaptophysin. Cells expressing Tag alone were never observed; however, normal enteroendocrine cells expressing synaptophysin but not Tag were readily visualized. This suggests that ITFTag tumor cells originate from the enteroendocrine cell lineage following a transforming event that results in Tag expression. ITFTag tumors closely resemble human small cell carcinomas of the colon, suggesting the possibility that these tumors might be derived from the enteroendocrine cell lineage as well.

Small-Cell Carcinomas of the Gastrointestinal Tract: A Review

Purpose

To improve our understanding of the entity of small-cell carcinoma (SmCC) of the gastrointestinal (GI) tract.

Methods

A MEDLINE search was done, using the terms “small cell carcinoma” or “oat cell carcinoma” combined with “gastrointestinal” or with any of the GI sites, for the period 1970 to 2003. The 138 eligible reports identified in this way were reviewed for clinical data.

Results

To date, approximately 544 cases of GI SmCC have been reported. The disease represents 0.1% to 1% of all GI malignancies, with the esophagus being the most common primary site. A majority of patients present with overt distant metastases. Systemic symptoms are common; ectopic hormonal secretion may occur. By light microscopy, GI SmCCs are essentially indistinguishable from primary pulmonary SmCC. The presence of non-SmCC components is common. Data from molecular analysis of the disease has identified some similarities to pulmonary SmCC. Chemotherapy represents the main treatment option, with modest impact on survival. In locoregional disease, the literature suggests that treatment be initiated using chemoradiotherapy and then, if metastatic disease is still excluded, surgical resection be considered. The disease is highly aggressive, and survival is in the range of several weeks for untreated patients and of 6 to 12 months for those receiving therapy.

Conclusion

SmCC of the GI tract is a rare and lethal disease. Although there are many similarities to pulmonary SmCC, some differences between the two entities are suggested. While chemotherapy can achieve significant palliation, surgery may have a potential impact on long-term survival of patients with locoregional disease.

Heterogeneous expression of neuroendocrine marker proteins in human undifferentiated carcinoma of the colon and rectum

The expression of neuroendocrine marker proteins in undifferentiated colorectal cancers has not yet been studied in great detail. Therefore, the survival of 20 patients with small cell undifferentiated colorectal cancers treated at our institution between 1982 and 1997 (0.8% of all operated colorectal carcinomas) was correlated with the extent of neuroendocrine differentiation. Chromogranin A, synaptophysin, syntaxin1, VAMP2, SNAP25, and alpha/beta-SNAP were used as neuroendocrine markers. Based on the degree of immunoreactivity for these marker proteins, tumors were divided into group 0 (<2% cells stained positive for neuroendocrine markers) and group 1 (>2% cells stained positive). Patients were followed up for at least 5 years or until death. Nine of twenty (45%) undifferentiated colorectal tumors expressed neuroendocrine markers (group 1). Only one patient of this group survived 2 years (11%), whereas the 2-year survival rate was 45.4% in group 0. Nine of eleven patients of group 0 were diagnosed in UICC stage I-III, whereas eight of nine tumors with expression of neuroendocrine markers were diagnosed in UICC stage IV (P = 0.002). Our results show that neuroendocrine differentiation is often seen in small cell undifferentiated colorectal cancer. It correlates with a more aggressive course of the disease.

The effectiveness of chemotherapy with cisplatin and 5-fluorouracil for recurrent small cell neuroendocrine carcinoma of the rectum: report of a case

We report herein the case of a 46-year-old-man with small cell neuroendocrine carcinoma (NEC) concomitant with large villous adenoma of the rectum, who underwent abdominoperineal resection with regional lymphnode dissection. The resected specimen was histologically found to contain a small lesion of NEC confined to the submucosa in the large adenoma. A computed tomography scan done 4 months postoperatively revealed recurrences in the liver, lymph nodes, and bone. Therefore, two cycles of sequential intravenous combined chemotherapy with standard doses of cisplatin and 5-fluorouracil (5-FU) were administered, after which the size of each tumor decreased remarkably. Nevertheless, the patient died 8 months after the operation. As there was a fair response of this tumor to the combined chemotherapy of cisplatin and 5-FU, this regimen against NEC of the colon and rectum should be given consideration.

Concordance of genetic alterations in poorly differentiated colorectal neuroendocrine carcinomas and associated adenocarcinomas

BACKGROUND

The histopathologic spectrum of colorectal neuroendocrine tumors ranges from benign to highly malignant. In this spectrum, poorly differentiated neuroendocrine carcinoma (PDNC) is the most aggressive type, characterized by early dissemination and a rapidly fatal course. Since it is unclear whether PDNC originates from neoplastic transformation of preexisting neuroectodermal cells, pluripotent epithelial stem cells, or adenocarcinoma precursor cells, we investigated the histogenesis of this type of cancer by performing genetic analyses on a series of colorectal tumors.

METHODS

Archived histologic sections of colorectal PDNC from nine patients were analyzed; gastrointestinal carcinoid tumor specimens from four patients were used as controls. The specimens were deparaffinized, microdissected, and analyzed genetically. After DNA extraction, polymerase chain reaction amplification was performed to investigate alteration (i.e., loss of heterozygosity [LOH]) of the APC (adenomatous polyposis coli), DCC (deleted in colorectal carcinoma), and p53 (also known as TP53) genes.

RESULTS

LOH of the APC, DCC, or p53 genes was observed in six of eight informative PDNC tumors; no LOH was detected in the carcinoid control specimens. Four of five informative PDNC tumors had associated adenocarcinoma; LOH of the APC and p53 genes in these tumors involved the same allele in both tissue components. Four of the five tumors with associated adenocarcinoma showed LOH of the DCC gene; in three of these four tumors, the PDNC and adenomatous components showed LOH of the same allele.

CONCLUSIONS

PDNC and associated adenocarcinoma appear to be derived from the same cell of origin, which is most likely either a pluripotent epithelial stem cell or an adenocarcinoma precursor cell.

Fine-needle aspiration cytology of metastatic small cell carcinoma of the colon: a report of three cases

Small cell carcinoma of the large intestine is a rare, extremely aggressive malignancy often associated with an overlying adenoma. We report three cases of metastatic small cell carcinoma of the colon diagnosed by fine-needle aspiration (FNA) biopsy. Two of the patients were women (ages 33 and 46 yr old) and one was a man (69 yr old). FNA biopsy established the diagnosis of metastatic small cell carcinoma involving the liver (2 cases) and soft tissue of the scapular region (1 case). In one patient, the FNA diagnosis of hepatic metastases preceded identification of the primary site. Subsequently, the patient was found to have a small cell carcinoma subadjacent to a colonic villous adenoma, illustrating the importance of investigating villous lesions of the colon in patients with metastatic small cell carcinoma of unknown primary origin (especially in non-smokers). All three cases showed the characteristic cytologic features of small cell carcinoma. Ancillary studies performed on aspirated material confirmed the diagnosis of small cell carcinoma in one case. Immunocytochemical studies revealed punctate cytokeratin and diffuse neuron-specific enolase (NSE) positivity of the malignant cells. Ultrastructurally neurosecretory granules were evident. To the best of our knowledge, this is the first FNA cytologic report of metastatic small cell carcinoma of the large intestine. This FNA report also demonstrates when a small cell carcinoma is detected in a metastatic site in a patient lacking a lung primary, a likely primary site could be adjacent or beneath a polypoid lesion of the colon.

Metastasis from small cell carcinoma of the lung producing acute appendicitis

A case of acute gangrenous appendicitis with perforation caused by metastatic small cell carcinoma of the lung in a 65 year old man is reported. The manifestation of appendicitis occurred more than 4 years after the diagnosis of the bronchogenic carcinoma. With longer survival of patients with disseminated tumors it is probable that new manifestations of those malignancies will be discovered. Acute appendicitis due to metastasis from a distant neoplasm should be considered in the differential diagnosis of right lower abdominal pain in the oncology patient.

Small cell neuroendocrine carcinoma of the rectum

Poorly differentiated small cell neuroendocrine (NE) carcinoma of the colon and rectum is a rare primary epithelial malignancy at this location. A case of a highly aggressive NE tumor of small cell type, combined with non-invasive well-differentiated papillary adenocarcinoma in villous adenoma is reported. The patient died rapidly with massive and progressive liver metastasis. The tumor cells were argyrophilic and diffusely immunoreactive for neuronspecific enolase and synaptophysin. Ultrastructural analysis disclosed NE-type cored granules in most of the small tumor cells. NE tumors of the colon and rectum are briefly reviewed.

Ectopic ACTH syndrome associated with anorectal carcinoma. Report of a case and review of the literature

A 25-year-old black homosexual was noted to be hypertensive, hypokalemic, and to have a rectal mass. Histopathology of the biopsied lesion revealed a mixture of poorly differentiated squamous cell and undifferentiated small cell carcinoma. Abdominopelvic CT showed multiple liver metastases, minimal local tumor extension, and normal adrenal glands. Despite aggressive treatment, he remained hypertensive and hypokalemic. Endocrine work-up revealed: normal 24-hr VMA and catecholamines, normal serum aldosterone and renin levels, elevated urinary free cortisol (3360 micrograms/24 hr), elevated serum cortisol (60 micrograms/dl), and elevated serum ACTH (1697 pg/dl). Liver biopsy confirmed metastatic anorectal carcinoma, and immunohistochemical stains of the rectal biopsy were positive for ACTH and neuron-specific enolase. Although many types of neoplasms have been associated with ectopic ACTH production, small cell carcinoma of the lung is the most common. While there are many reports of colorectal and anorectal neuroendocrine small cell carcinomas, few of these tumors have been associated with clinical ectopic hormone production. This case represents the first report of the ectopic ACTH syndrome associated with anorectal carcinoma.

Small cell carcinoma of the anus in a human HIV carrier: report of a case

We report herein a rare case of metastatic anal small cell neuroendocrine carcinoma in a human immunodeficiency virus (HIV) carrier. This is only the third case of an HIV infection associated with the rare anorectal small cell carcinoma to be reported in the world literature. Although radiation and abdominoperineal resection cannot provide a cure, systemic chemotherapy consisting of cisplatin and etoposide (VP-16) achieved complete resolution of all the indicator lesions. The values of the T-helper: T-suppressor )OKT4:OKT8) ratio and beta 2-microglobulin showed that the state of immunodeficiency caused by the HIV did not become worse during either major surgery or systemic chemotherapy.

c-myc antisense oligonucleotides inhibit the colony-forming capacity of Colo 320 colonic carcinoma cells

Colo 320 cells are colonic carcinoma cells known to express abundant c-myc mRNA. Based on the response of several hematopoietic cell lines to chemical inducers of differentiation, we reasoned that such agents might have similar inductive activity in Colo 320 cells. Accordingly, we exposed Colo 320 cells to 5 mM sodium butyrate (NaBT) for 7 d. C-myc expression decreased threefold and self-replicative potential decreased (defined as a greater than 60% decrease in colony-forming capacity in soft agar that did not contain inducer). In an effort to demonstrate a direct cause and effect between myc expression and the colony-forming capacity of Colo 320 cells, we exposed these cells to a 15-base antisense c-myc oligonucleotide (complementary to the translation initiation region of exon II). Cells were also exposed to equimolar (20 microM) amounts of sense and missense oligonucleotides. Subsequently, cells were incubated at 10, 20, 30, and 40 microM antisense DNA for 16 h, then washed and plated in oligonucleotide-free agar medium. We demonstrated that: (a) the oligomers were stable in the extracellular medium and in the cell cytoplasm; (b) the uptake of the oligonucleotides was 0.7%; (c) sense and missense oligonucleotides had no effect on colony-forming capacity; and (d) the antisense c-myc oligonucleotide resulted in a 40-75% concentration-dependent decrease in colony-forming capacity. The specific inhibition of colony-forming capacity by antisense DNA suggests that the role of myc expression in Colo 320 cells is similar to its role in hematopoiesis, and that the failure to inhibit myc expression maintains colony-forming capacity. This system provides a new strategy for inducing differentiation and may provide further insight into the genetic factors that govern the process of colonic carcinogenesis.

Small cell carcinoma of the gallbladder combined with adenocarcinoma

A rare case of small cell carcinoma (SCC) of the gallbladder combined with adenocarcinoma is reported. The patient was a 70-year-old Japanese man, who died of the disease shortly after the onset of symptoms. Autopsy disclosed a small tumor (1.0 cm in longest diameter) in the fundus of the gallbladder, with widespread metastasis. Histochemically, the tumor cells showed negative reactions for argyrophilic and argentaffin stainings, a weak immunohistochemical reaction only for neuron-specific enolase, and negative reactions for all of the other neurosecretory markers used, including neurofilament, chromogranin, somatostatin, gastrin and leu-7. However, electron microscopic examination revealed a few typical neurosecretory granules (NSG) in the cytoplasm of some tumor cells. We suggest that: 1. The presence of NSG in the cytoplasm of tumor cells is the most reliable diagnostic criterion for SCC. 2. SCC, at least the combined type, arises from a multipotential stem cell.

'Neuroendocrine' differentiation in primary neoplasms of the liver

Thirty primary liver neoplasms (16 hepatocellular, nine biliary, and five epithelioid haemangioendotheliomas) were studied for the expression of the general 'neuroendocrine' markers, neurone specific enolase (NSE) and protein gene product 9.5 (PGP 9.5). Grimelius silver staining for neurosecretory granules and immunostaining for S100 protein, HMB-45, vasoactive intestinal polypeptide (VIP), and calcitonin were also performed. Eleven of the 16 hepatocellular carcinomas stained positively for PGP 9.5, four for NSE, six for HMB-45, and two for S100 protein. Seven exhibited granular staining by the Grimelius method; eight showed immunostaining for VIP, and two for calcitonin. Three of the five haemangioendotheliomas demonstrated positive immunostaining for PGP 9.5, and two for NSE; of the nine biliary carcinomas, two showed staining for PGP 9.5 and NSE, and four contained cells staining with the Grimelius technique. Primary neoplasms of liver may show 'neuroendocrine' differentiation and this aspect of their phenotypic expression has to be considered before predicting the site of origin of a tumour in the liver.