Pathologic Features of Primary and Metastatic Hepatic Malignancies.

In the mammalian liver, 60 % of the cellular components are hepatocytes while the remainder (35 %) includes biliary epithelium, Kupffer cells, endothelial cells, fat storing cells and connective tissue cells. Although neoplasms of hepatocytes are the most common, a significant number of both benign and malignant primary liver neoplasms arising from other cell types can develop, such as tumors of bile duct epithelium (Table 1). In addition, the liver is one of the most susceptible sites for metastatic tumors arising from other organs of the body. Not too long ago, liver tumors were left untreated because the liver was considered a complex and mysterious organ inaccessible to surgery. Advances in imaging procedures and surgical techniques over the past 40 years have revolutionized the approaches to the treatment of benign and malignant liver tumors. Subsegmentectomy, segmentectomy, lobectomy, and transplantation are routinely performed for the treatment of primary and metastatic liver tumors with minimal morbidity and mortality. Since accurate diagnosis remains the key to clinical and surgical management, the emphasis of this chapter is on classification, morphological features and differential diagnosis of malignant neoplasms of the liver.

Colorectal Cancer Screening, Version 1.2015.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colorectal Cancer Screening provide recommendations for selecting individuals for colorectal cancer screening, and for evaluation and follow-up of colon polyps. These NCCN Guidelines Insights summarize major discussion points of the 2015 NCCN Colorectal Cancer Screening panel meeting. Major discussion topics this year were the state of evidence for CT colonography and stool DNA testing, bowel preparation procedures for colonoscopy, and guidelines for patients with a positive family history of colorectal cancer.

Dissociation of hepatic insulin resistance from susceptibility of nonalcoholic fatty liver disease induced by a high-fat and high-carbohydrate diet in mice.

Liver steatosis in nonalcoholic fatty liver disease is affected by genetics and diet. It is associated with insulin resistance (IR) in hepatic and peripheral tissues. Here, we aimed to characterize the severity of diet-induced steatosis, obesity, and IR in two phylogenetically distant mouse strains, C57BL/6J and DBA/2J. To this end, mice (male, 8 wk old) were fed a high-fat and high-carbohydrate (HFHC) or control diet for 16 wk followed by the application of a combination of classic physiological, biochemical, and pathological studies to determine obesity and hepatic steatosis. Peripheral IR was characterized by measuring blood glucose level, serum insulin level, homeostasis model assessment of IR, glucose intolerance, insulin intolerance, and AKT phosphorylation in adipose tissues, whereas the level of hepatic IR was determined by measuring insulin-triggered hepatic AKT phosphorylation. We discovered that both C57BL/6J and DBA/2J mice developed obesity to a similar degree without the feature of liver inflammation after being fed an HFHC diet for 16 wk. C57BL/6J mice in the HFHC diet group exhibited severe pan-lobular steatosis, a marked increase in hepatic triglyceride levels, and profound peripheral IR. In contrast, DBA/2J mice in the HFHC diet group developed only a mild degree of pericentrilobular hepatic steatosis that was associated with moderate changes in peripheral IR. Interestingly, both C57BL/6J and DBA/2J developed severe hepatic IR after HFHC diet treatment. Collectively, these data suggest that the severity of diet-induced hepatic steatosis is correlated to the level of peripheral IR, not with the severity of obesity and hepatic IR. Peripheral rather than hepatic IR is a dominant factor of pathophysiology in nonalcoholic fatty liver disease.

Sustained activation of PPARα by endogenous ligands increases hepatic fatty acid oxidation and prevents obesity in ob/ob mice.

Obesity, a major health concern, results from an imbalance between energy intake and expenditure. Leptin-deficient ob/ob mice are paradigmatic of obesity, resulting from excess energy intake and storage. Mice lacking acyl-CoA oxidase 1 (Acox1), the first enzyme of the peroxisomal fatty acid ß-oxidation system, are characterized by increased energy expenditure and a lean body phenotype caused by sustained activation of peroxisome proliferator-activated receptor α (PPARα) by endogenous ligands in liver that remain unmetabolized in the absence of Acox1. We generated ob/ob mice deficient in Acox1 (Acox1(-/-)) to determine how the activation of PPARα by endogenous ligands might affect the obesity of ob/ob mice. In contrast to Acox1(-/-) (14.3±1.2 g at 6 mo) and the Acox1-deficient (ob/ob) double-mutant mice (23.8±4.6 g at 6 mo), the ob/ob mice are severely obese (54.3±3.2 g at 6 mo) and had significantly more (P<0.01) epididymal fat content. The resistance of Acox1(-/-)/ob/ob mice to obesity is due to increased PPARα-mediated up-regulation of genes involved in fatty acid oxidation in liver. Activation of PPARα in Acox1-deficient ob/ob mice also reduces serum glucose and insulin (P<0.05) and improves glucose tolerance and insulin sensitivity. Further, PPARα activation reduces hepatic steatosis and increases hepatocellular regenerative response in Acox1(-/-)/ob/ob mice at a more accelerated pace than in mice lacking only Acox1. However, Acox1(-/-)/ob/ob mice manifest hepatic endoplasmic reticulum (ER) stress and also develop hepatocellular carcinomas (8 of 8 mice) similar to those observed in Acox1(-/-) mice (10 of 10 mice), but unlike in ob/ob (0 of 14 mice) and OB/OB (0 of 6 mice) mice, suggesting that superimposed ER stress and PPARα activation contribute to carcinogenesis in a fatty liver. Finally, absence of Acox1 in ob/ob mice can impart resistance to high-fat diet (60% fat)-induced obesity, and their liver had significantly (P<0.01) more cell proliferation. These studies with Acox1(-/-)/ob/ob mice indicate that sustained activation of lipid-sensing nuclear receptor PPARα attenuates obesity and restores glucose homeostasis by ameliorating insulin resistance but increases the risk for liver cancer development, in part related to excess energy combustion.

Colorectal cancer screening.

Mortality from colorectal cancer can be reduced by early diagnosis and by cancer prevention through polypectomy. These NCCN Guidelines for Colorectal Cancer Screening describe various colorectal screening modalities and recommended screening schedules for patients at average or increased risk of developing colorectal cancer. In addition, the guidelines provide recommendations for the management of patients with high-risk colorectal cancer syndromes, including Lynch syndrome. Screening approaches for Lynch syndrome are also described.

Progressive endoplasmic reticulum stress contributes to hepatocarcinogenesis in fatty acyl-CoA oxidase 1-deficient mice.

Fatty acyl-coenzyme A oxidase 1 (ACOX1) knockout (ACOX1(-/-)) mice manifest hepatic metabolic derangements that lead to the development of steatohepatitis, hepatocellular regeneration, spontaneous peroxisome proliferation, and hepatocellular carcinomas. Deficiency of ACOX1 results in unmetabolized substrates of this enzyme that function as biological ligands for peroxisome proliferator-activated receptor-α (PPARα) in liver. Here we demonstrate that sustained activation of PPARα in ACOX1(-/-) mouse liver by these ACOX1 substrates results in endoplasmic reticulum (ER) stress. Overexpression of transcriptional regulator p8 and its ER stress-related effectors such as the pseudokinase tribbles homolog 3, activating transcription factor 4, and transcription factor CCAAT/-enhancer-binding protein homologous protein as well as phosphorylation of eukaryotic translation initiation factor 2α, indicate the induction of unfolded protein response signaling in the ACOX1(-/-) mouse liver. We also show here that, in the liver, p8 is a target for all three PPAR isoforms (-α, -ß, and -γ), which interact with peroxisome proliferator response elements in p8 promoter. Sustained activation of p8 and unfolded protein response-associated ER stress in ACOX1(-/-) mouse liver contributes to hepatocyte apoptosis and liver cell proliferation culminating in the development of hepatocarcinogenesis. We also demonstrate that human ACOX1 transgene is functional in ACOX1(-/-) mice and effectively prevents metabolic dysfunctions that lead to ER stress and carcinogenic effects. Taken together, our data indicate that progressive PPARα- and p8-mediated ER stress contribute to the hepatocarcinogenesis in ACOX1(-/-) mice.

Transcription coactivator mediator subunit MED1 is required for the development of fatty liver in the mouse.

UNLABELLED: Peroxisome proliferator-activated receptor-γ (PPARγ), a nuclear receptor, when overexpressed in liver stimulates the induction of adipocyte-specific and lipogenesis-related genes and causes hepatic steatosis. We report here that Mediator 1 (MED1; also known as PBP or TRAP220), a key subunit of the Mediator complex, is required for high-fat diet-induced hepatic steatosis as well as PPARγ-stimulated adipogenic hepatic steatosis. Mediator forms the bridge between transcriptional activators and RNA polymerase II. MED1 interacts with nuclear receptors such as PPARγ and other transcriptional activators. Liver-specific MED1 knockout (MED1(ΔLiv) ) mice, when fed a high-fat (60% kcal fat) diet for up to 4 months failed to develop fatty liver. Similarly, MED1(ΔLiv) mice injected with adenovirus-PPARγ (Ad/PPARγ) by tail vein also did not develop fatty liver, whereas mice with MED1 (MED1(fl/fl) ) fed a high-fat diet or injected with Ad/PPARγ developed severe hepatic steatosis. Gene expression profiling and northern blot analyses of Ad/PPARγ-injected mouse livers showed impaired induction in MED1(ΔLiv) mouse liver of adipogenic markers, such as aP2, adipsin, adiponectin, and lipid droplet-associated genes, including caveolin-1, CideA, S3-12, and others. These adipocyte-specific and lipogenesis-related genes are strongly induced in MED1(fl/fl) mouse liver in response to Ad/PPARγ. Re-expression of MED1 using adenovirally-driven MED1 (Ad/MED1) in MED1(ΔLiv) mouse liver restored PPARγ-stimulated hepatic adipogenic response. These studies also demonstrate that disruption of genes encoding other coactivators such as SRC-1, PRIC285, PRIP, and PIMT had no effect on hepatic adipogenesis induced by PPARγ overexpression. CONCLUSION: We conclude that transcription coactivator MED1 is required for high-fat diet-induced and PPARγ-stimulated fatty liver development, which suggests that MED1 may be considered a potential therapeutic target for hepatic steatosis. (HEPATOLOGY 2011;).

Transcription coactivator PBP/MED1-deficient hepatocytes are not susceptible to diethylnitrosamine-induced hepatocarcinogenesis in the mouse.

Nuclear receptor coactivator [peroxisome proliferator-activated receptor-binding protein (PBP)/mediator subunit 1 (MED1)] is a critical component of the mediator transcription complex. Disruption of this gene in the mouse results in embryonic lethality. Using the PBP/MED1 liver conditional null (PBP/MED1(DeltaLiv)) mice, we reported that PBP/MED1 is essential for liver regeneration and the peroxisome proliferator-activated receptor alpha ligand Wy-14,643-induced receptor-mediated hepatocarcinogenesis. We now examined the role of PBP/MED1 in genotoxic chemical carcinogen diethylnitrosamine (DEN)-induced and phenobarbital-promoted hepatocarcinogenesis. The carcinogenic process was initiated by a single intraperitoneal injection of DEN at 14 days of age and initiated cells were promoted with phenobarbital (PB) (0.05%) in drinking water. PBP/MED1(DeltaLiv) mice, killed at 1, 4 and 12 weeks, revealed a striking proliferative response of few residual PBP/MED1-positive hepatocytes that escaped Cre-mediated deletion of PBP/MED1 gene. No proliferative expansion of PBP/MED1 null hepatocytes was noted in the PBP/MED1(DeltaLiv) mouse livers. Multiple hepatocellular carcinomas (HCCs) developed in the DEN-initiated PBP/MED1(fl/fl) and PBP/MED1(DeltaLiv) mice, 1 year after the PB promotion. Of interest is that all HCC developing in PBP/MED1(DeltaLiv) mice were PBP/MED1 positive. None of the tumors was PBP/MED1 negative implying that hepatocytes deficient in PBP/MED1 are not susceptible to neoplastic conversion. HCC that developed in PBP/MED1(DeltaLiv) mouse livers were transplantable in athymic nude mice and these maintained PBP/MED1(fl/fl) genotype. PBP/MED1(fl/fl) HCC cell line derived from these tumors expressed PBP/MED1 and deletion of PBP/MED1(fl/fl) allele by adeno-Cre injection into tumors caused necrosis of tumor cells. These results indicate that PBP/MED1 is essential for the development of HCC in the mouse.

Reversal of mouse Acyl-CoA oxidase 1 (ACOX1) null phenotype by human ACOX1b isoform [corrected].

Disruption of the peroxisomal acyl-CoA oxidase 1 (Acox1) gene in the mouse results in the development of severe microvesicular hepatic steatosis and sustained activation of peroxisome proliferator-activated receptor-alpha (PPARalpha). These mice manifest spontaneous massive peroxisome proliferation in regenerating hepatocytes and eventually develop hepatocellular carcinomas. Human ACOX1, the first and rate-limiting enzyme of the peroxisomal beta-oxidation pathway, has two isoforms including ACOX1a and ACOX1b, transcribed from a single gene. As ACOX1a shows reduced activity toward palmitoyl-CoA as compared with ACOX1b, we used adenovirally driven ACOX1a and ACOX1b to investigate their efficacy in the reversal of hepatic phenotype in Acox1(-/-) mice. In this study, we show that human ACOX1b is markedly effective in reversing the ACOX1 null phenotype in the mouse. In addition, expression of human ACOX1b was found to restore the production of nervonic (24:1) acid and had a negative impact on the recruitment of coactivators to the PPARalpha-response unit, which suggests that nervonic acid might well be an endogenous PPARalpha antagonist, with nervonoyl-CoA probably being the active form of nervonic acid. In contrast, restoration of docosahexaenoic (22:6) acid level, a retinoid-X-receptor (RXRalpha) agonist, was dependent on the concomitant hepatic expression of both ACOX1a and ACOX1b isoforms. This is accompanied by a specific recruitment of RXRalpha and coactivators to the PPARalpha-response unit. The human ACOX1b isoform is more effective than the ACOX1a isoform in reversing the Acox1 null phenotype in the mouse. Substrate utilization differences between the two ACOX1 isoforms may explain the reason why ACOX1b is more effective in metabolizing PPARalpha ligands.

Pancreatic adenocarcinoma in type 2 progressive familial intrahepatic cholestasis.

BACKGROUND: BSEP disease results from mutations in ABCB11, which encodes the bile salt export pump (BSEP). BSEP disease is associated with an increased risk of hepatobiliary cancer. CASE PRESENTATION: A 36 year old woman with BSEP disease developed pancreatic adenocarcinoma at age 36. She had been treated with a biliary diversion at age 18. A 1.7 x 1.3 cm mass was detected in the pancreas on abdominal CT scan. A 2 cm mass lesion was found at the neck and proximal body of the pancreas. Pathology demonstrated a grade 2-3 adenocarcinoma with invasion into the peripancreatic fat. CONCLUSIONS: Clinicians should be aware of the possibility of pancreatic adenocarcinoma in patients with BSEP disease.

Conditional ablation of mediator subunit MED1 (MED1/PPARBP) gene in mouse liver attenuates glucocorticoid receptor agonist dexamethasone-induced hepatic steatosis.

Glucocorticoid receptor (GR) agonist dexamethasone (Dex) induces hepatic steatosis and enhances constitutive androstane receptor (CAR) expression in the liver. CAR is known to worsen hepatic injury in nonalcoholic hepatic steatosis. Because transcription coactivator MED1/PPARBP gene is required for GR- and CAR-mediated transcriptional activation, we hypothesized that disruption of MED1/PPARBP gene in liver cells would result in the attenuation of Dex-induced hepatic steatosis. Here we show that liver-specific disruption of MED1 gene (MED1(delta Liv)) improves Dex-induced steatotic phenotype in the liver. In wild-type mice Dex induced severe hepatic steatosis and caused reduction in medium- and short-chain acyl-CoA dehydrogenases that are responsible for mitochondrial beta-oxidation. In contrast, Dex did not induce hepatic steatosis in mice conditionally null for hepatic MED1, as it failed to inhibit fatty acid oxidation enzymes in the liver. MED1(delta Liv) livers had lower levels of GR-regulated CAR mRNA compared to wild-type mouse livers. Microarray gene expression profiling showed that absence of MED1 affects the expression of the GR-regulated genes responsible for energy metabolism in the liver. These results establish that absence of MED1 in the liver diminishes Dex-induced hepatic steatosis by altering the GR- and CAR-dependent gene functions.

Ectopic hamartomatous thymoma in an immunocompromised male.

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm classically occurring in the lower neck of adult males. Here we present a case of EHT occurring in a 43-year-old immunocompromised male and a brief review of existing literature. The patient presented with a palpable mass overlying the left clavicle which, on imaging, showed a solitary nodule possibly eroding the cortical bone. A biopsy predominantly showed spindle cells that were immunopositive for keratin AE1/AE3 as well as weakly positive for CD99, SMA, and CD34. A diagnosis of synovial sarcoma was favored; at which point surgical resection was performed. The resected mass was well-demarcated with a tan-yellow cut surface. Microscopically, the lesion was composed of a mixture of spindle cells, glands, and mature adipose tissue. The spindle cells were plump with bland nuclei, and the epithelial component showed morphology similar to glands of salivary or breast tissue with a bilayered appearance (luminal and basal). No pleomorphism, mitotic figures, or necrosis was present. Immunohistochemical stains were performed and showed the spindle cells to express a myoepithelial phenotype (cytokeratin AE1/AE3, p63, calponin positive). The glands showed SMA and p63 positivity in the basal cells (similar to salivary gland and breast). Overall, given the clinical context, histomorphologic, and immunohistochemical profile, a diagnosis of EHT was made. At 12 months of follow-up there was no evidence of recurrence.

Solitary fibrous tumor of the pancreas: case report with cytologic and surgical pathology correlation and review of the literature.

CONTEXT: Solitary fibrous tumor is an uncommon spindle cell tumor which can occur in a variety of locations. Four cases of pancreatic solitary fibrous tumor have been reported in the literature. CASE REPORT: We report the fifth case of pancreatic solitary fibrous tumor in a 78-year-old woman who presented with back pain and weight loss. Imaging studies were suggestive of an endocrine tumor. Endoscopic ultrasound with fine needle aspiration was performed and revealed a benign mesenchymal tumor, which is the first successful report of cytology on a pancreatic solitary fibrous tumor. The patient underwent a distal pancreatectomy with resection of the mass which was diagnosed as solitary fibrous tumor, supported by immunohistochemical studies showing positivity for CD99, vimentin, bcl-2, and CD34. CONCLUSION: Diagnosing pancreatic solitary fibrous tumor is challenging due to its rarity, nonspecific clinical presentation, and difficulty to be radiologically distinguished from other pancreatic lesions. These issues as well as the prior four cases are discussed.

Extranodal Rosai-Dorfman Disease With Mucosal Involvement of the Stomach in a Background of Autoimmune Atrophic Gastritis.

Rosai-Dorfman disease (RDD), or sinus histiocytosis with massive lymphadenopathy, has been described involving both lymph nodes and extranodal sites, but extranodal RDD rarely involves the gastrointestinal tract. Although the etiology is unclear, several risk factors have been shown to be highly associated with this disease process, including viral infection and immune alterations. In this article, we present a case of a 79-year-old male with a history of autoimmune atrophic gastritis and multiple carcinoid tumors of the stomach presenting with a new stomach mass. An additional large sigmoid colon mass and adjacent enlarged lymph node was identified through imaging, prior to surgery. Through extensive pathologic analysis, we identified the first case of predominant extranodal RDD involving gastric mucosa and submucosa in a background of atrophic gastritis, with additional involvement of the sigmoid colon. Based on this case and literature review, we further discuss possible risk factors and pathogenesis of this disease process.

Transcription coactivator PRIP, the peroxisome proliferator-activated receptor (PPAR)-interacting protein, is redundant for the function of nuclear receptors PParalpha and CAR, the constitutive androstane receptor, in mouse liver.

Disruption of the genes encoding for the transcription coactivators, peroxisome proliferator-activated receptor (PPAR)-interacting protein (PRIP/ASC-2/RAP250/TRBP/NRC) and PPAR-binding protein (PBP/TRAP220/DRIP205/MED1), results in embryonic lethality by affecting placental and multiorgan development. Targeted deletion of coactivator PBP gene in liver parenchymal cells (PBP(LIV-/-)) results in the near abrogation of the induction of PPARalpha and CAR (constitutive androstane receptor)-regulated genes in liver. Here, we show that targeted deletion of coactivator PRIP gene in liver (PRIP(LIV-/-)) does not affect the induction of PPARalpha-regulated pleiotropic responses, including hepatomegaly, hepatic peroxisome proliferation, and induction of mRNAs of genes involved in fatty acid oxidation system, indicating that PRIP is not essential for PPARalpha-mediated transcriptional activity. We also provide additional data to show that liver-specific deletion of PRIP gene does not interfere with the induction of genes regulated by nuclear receptor CAR. Furthermore, disruption of PRIP gene in liver did not alter zoxazolamine-induced paralysis, and acetaminophen-induced hepatotoxicity. Studies with adenovirally driven EGFP-CAR expression in liver demonstrated that, unlike PBP, the absence of PRIP does not prevent phenobarbital-mediated nuclear translocation/retention of the receptor CAR in liver in vivo and cultured hepatocytes in vitro. These results show that PRIP deficiency in liver does not interfere with the function of nuclear receptors PPARalpha and CAR. The dependence of PPARalpha- and CAR-regulated gene transcription on coactivator PBP but not on PRIP attests to the existence of coactivator selectivity in nuclear receptor function.

Thymidylate synthase protein expression in primary colorectal cancer: lack of correlation with outcome and response to fluorouracil in metastatic disease sites.

PURPOSE: The aim of this study was to investigate the utility of quantitating thymidylate synthase (TS) in the primary tumor as a surrogate for metastatic disease sites to predict the likelihood of response and outcome to fluorouracil (FU) treatment in patients with metastatic colorectal cancer. METHODS: TS protein expression was evaluated using the TS 106 antibody and the avidin biotin labeling immunohistochemical technique in primary tumor samples from 219 patients with metastatic colorectal cancer. The patients were a representative sample of those patients enrolled into the Eastern Cooperative Oncology Group E2290 protocol that evaluated five separate FU-containing regimens in patients with metastatic residual or recurrent colorectal carcinoma. RESULTS: Our retrospective analysis found that the level and extent of TS protein expression in the primary tumor did not correlate with overall survival in patients with metastatic or recurrent colorectal cancer. A trend toward a direct correlation between the level of TS protein expression and response was noted in tumors that expressed high TS levels. This response advantage for patients expressing high TS levels in the primary tumor was apparent regardless of what FU-based treatment the patient received but was most apparent in the subgroup treated with leucovorin, in which the level of TS expression and response to FU and leucovorin reached statistical significance (P =.034). No significant interaction could be detected between the addition of leucovorin to FU and the level of TS expression in the primary tumor. CONCLUSION: This study demonstrated that measurement of TS protein levels in the primary tumor tissue does not aid in predicting outcome or response to FU in a metastatic disease site. These assays must be performed on biopsy tissue from the metastatic disease site that is used to radiologically assess response and outcome to treatment.

Immunohistochemical detection of the beta4 integrin subunit in pancreatic adenocarcinoma.

The expression of the beta4 integrin subunit protein in pancreatic cancer was investigated using routine immunohistochemical methods on paraffin-embedded archival material. Forty-eight cases of pancreatic ductal adenocarcinoma were immunostained with a monoclonal antibody to the beta4 integrin subunit, and the extent of staining was compared with that seen in non-cancerous pancreatic tissues, including 15 separate cases of chronic pancreatitis and 6 sections from normal pancreas. We found that the beta4 integrin subunit protein was overexpressed in the majority of pancreatic carcinoma cases tested, whereas chronic pancreatitis and normal pancreas did not display substantial levels of expression.

Expression of androgen receptor and prostate-specific antigen in male breast carcinoma.

BACKGROUND: The androgen-regulated proteins prostate-specific antigen (PSA) and prostate-specific acid phosphatase (PSAP) are present in high concentrations in normal prostate and prostatic cancer and are considered to be tissue-specific to prostate. These markers are commonly used to diagnose metastatic prostate carcinoma at various sites including the male breast. However, expression of these two proteins in tumors arising in tissues regulated by androgens such as male breast carcinoma has not been thoroughly evaluated. METHODS: In this study we analyzed the expression of PSA, PSAP and androgen receptor (AR) by immunohistochemistry in 26 cases of male breast carcinomas and correlated these with the expression of other prognostic markers. RESULTS: AR, PSA and PSAP expression was observed in 81%, 23% and 0% of carcinomas, respectively. Combined expression of AR and PSA was observed in only four tumors. CONCLUSION: Although the biological significance of PSA expression in male breast carcinomas is not clear, caution should be exercised when it is used as a diagnostic marker of metastatic prostate carcinoma.

Signet-ring cell change versus signet-ring cell carcinoma: a comparative analysis.

Signet-ring cell change (SCC) is a nonneoplastic condition that morphologically simulates signet-ring cell carcinoma (SRCA). The few case reports on SCC have focused on morphologic characteristics in distinguishing benign from malignant. In biopsy specimens, however, SCC can be easily confused with SRCA, which often demonstrates innocuous cytologic features. The object of this study is twofold: 1) to report 14 additional cases of SCC, comparing their morphologic and phenotypic features with that of SRCA; and 2) to evaluate the incidence of SCC in pseudomembranous colitis. Paraffin sections of biopsy or resection specimens containing focal or extensive SCC and 5 cases of colonic SRCA were stained with hematoxylin and eosin, periodic-acid Schiff stain with and without diastase digestion, and by standard ABC immunoperoxidase procedure using antibodies to E-cadherin, p53, and Ki-67. Both cells in SCC and SRCA were strongly positive for neutral mucins. Cells in SCC were strongly positive for E-cadherin and negative for p53 and Ki-67. In contrast, cells in SRCA were strongly positive for p53, exhibited high proliferation, and demonstrated absent or weak positivity for E-cadherin. Although SCC is not well recognized in pseudomembranous colitis, the incidence is fairly high: 14 of 50 (28%) cases showed variable numbers of signet-ring cells. Extensive SCC, although rare, can occur in different clinical conditions and can be easily mistaken for SRCA. When in doubt, routine immunohistochemical stains such as p53, Ki-67, and E-cadherin can help to differentiate SCC from SRCA.