Mast cells play an important role in chlamydia pneumoniae lung infection by facilitating immune cell recruitment into the airway.

Mast cells are known as central players in allergy and anaphylaxis, and they play a pivotal role in host defense against certain pathogens. Chlamydia pneumoniae is an important human pathogen, but it is unclear what role mast cells play during C. pneumoniae infection. We infected C57BL/6 (wild-type [WT]) and mast cell-deficient mice (Kit(W-sh/W-sh) [Wsh]) with C. pneumoniae. Wsh mice showed improved survival compared with WT mice, with fewer cells in Wsh bronchoalveolar lavage fluid (BALF), despite similar levels of cytokines and chemokines. We also found a more rapid clearance of bacteria from the lungs of Wsh mice compared with WT mice. Cromolyn, a mast cell stabilizer, reduced BALF cells and bacterial burden similar to the levels seen in Wsh mice; conversely, Compound 48/80, a mast cell degranulator, increased the number of BALF cells and bacterial burden. Histology showed that WT lungs had diffuse inflammation, whereas Wsh mice had patchy accumulations of neutrophils and perivascular accumulations of lymphocytes. Infected Wsh mice had reduced amounts of matrix metalloprotease-9 in BALF and were resistant to epithelial integral membrane protein degradation, suggesting that barrier integrity remains intact in Wsh mice. Mast cell reconstitution in Wsh mice led to enhanced bacterial growth and normal epithelial integral membrane protein degradation, highlighting the specific role of mast cells in this model. These data suggest that mast cells play a detrimental role during C. pneumoniae infection by facilitating immune cell infiltration into the airspace and providing a more favorable replicative environment for C. pneumoniae.

Angiotensin-converting enzyme is required for normal myelopoiesis.

Inhibition of angiotensin-converting enzyme (ACE) induces anemia in humans and mice, but it is unclear whether ACE is involved in other aspects of hematopoiesis. Here, we systemically evaluated ACE-knockout (KO) mice and found myelopoietic abnormalities characterized by increased bone marrow myeloblasts and myelocytes, as well as extramedullary myelopoiesis. Peritoneal macrophages from ACE-KO mice were deficient in the production of effector molecules, such as tumor necrosis factor-α, interleukin-12p40, and CD86 when stimulated with lipopolysaccharide and interferon-γ. ACE-KO mice were more susceptible to Staphylococcus aureus infection. Further studies using total or fractionated bone marrows revealed that ACE regulates myeloid proliferation, differentiation, and functional maturation via angiotensin II and substance P and through the angiotensin II receptor type 1 and substance P neurokinin 1 receptors. Angiotensin II was correlated with CCAAT-enhancer-binding protein-α up-regulation during myelopoiesis. Angiotensin II supplementation of ACE-KO mice rescued macrophage functional maturation. These results demonstrate a previous unrecognized significant role for ACE in myelopoiesis and imply new perspectives for manipulating myeloid cell expansion and maturation.

The NOD/RIP2 pathway is essential for host defenses against Chlamydophila pneumoniae lung infection.

Here we investigated the role of the Nod/Rip2 pathway in host responses to Chlamydophila pneumoniae-induced pneumonia in mice. Rip2(-/-) mice infected with C. pneumoniae exhibited impaired iNOS expression and NO production, and delayed neutrophil recruitment to the lungs. Levels of IL-6 and IFN-gamma levels as well as KC and MIP-2 levels in bronchoalveolar lavage fluid (BALF) were significantly decreased in Rip2(-/-) mice compared to wild-type (WT) mice at day 3. Rip2(-/-) mice showed significant delay in bacterial clearance from the lungs and developed more severe and chronic lung inflammation that continued even on day 35 and led to increased mortality, whereas WT mice cleared the bacterial load, recovered from acute pneumonia, and survived. Both Nod1(-/-) and Nod2(-/-) mice also showed delayed bacterial clearance, suggesting that C. pneumoniae is recognized by both of these intracellular receptors. Bone marrow chimera experiments demonstrated that Rip2 in BM-derived cells rather than non-hematopoietic stromal cells played a key role in host responses in the lungs and clearance of C. pneumoniae. Furthermore, adoptive transfer of WT macrophages intratracheally was able to rescue the bacterial clearance defect in Rip2(-/-) mice. These results demonstrate that in addition to the TLR/MyD88 pathway, the Nod/Rip2 signaling pathway also plays a significant role in intracellular recognition, innate immune host responses, and ultimately has a decisive impact on clearance of C. pneumoniae from the lungs and survival of the infectious challenge.

Lynch syndrome among gynecologic oncology patients meeting Bethesda guidelines for screening.

OBJECTIVE: Lynch syndrome (LS) is characterized by a high lifetime incidence of colorectal cancer and gynecologic malignancies such as endometrial and ovarian cancer. Identification of LS families is important as it allows for heightened cancer screening which decreases colorectal cancer mortality. The original 1996 Bethesda guidelines included two gynecologic populations that should be further evaluated for LS: those with endometrial cancer before the age of 45 years and those with two LS-related cancers (i.e. synchronous endometrial and ovarian cancer). Our study aims to estimate the prevalence of LS in these two populations. METHODS: We utilized a diagnostic algorithm that included immunohistochemistry for mismatch repair protein expression followed by selective evaluation for microsatellite instability and MLH1 gene promoter methylation. RESULTS: Among 72 eligible patients, 9 (12%) had molecular findings consistent with LS: 6/50 (12%) in the early-onset endometrial cancer group and 3/22 (14%) in the synchronous primary cancer group. In an additional 3 cases, MLH1 silencing was due to promoter methylation: 1/50 (2%) in the early-onset endometrial cancer group and 2/22 (9%) in the synchronous primary cancer group. Of the 9 women with molecular criteria suggesting LS, only three had pedigrees meeting the Amsterdam criteria. CONCLUSIONS: A diagnostic algorithm can identify patients with LS and those who warrant further genetic testing. Our findings reinforce the recommendation that women diagnosed with endometrial cancer before the age of 45 years and women with synchronous endometrial and ovarian cancer be screened for LS, irrespective of family history.

Large-cell transformation of a composite lymphoma.

Composite lymphoma is a rarely reported entity, defined as two or more morphologically distinct types of lymphoma at the same anatomic site, occurring either synchronously or metachronously. Since 1978, about 100 case reports of composite lymphoma have been cited, many involving combinations of low-grade B-cell lymphomas. To our knowledge, no cases of large-cell transformation of composite lymphoma have yet been described. We report the case of a patient who presented with diffuse large B-cell lymphoma (DLBCL) fifteen years after successful treatment for a mature B-cell lymphoma. Reassessment of the patient's lymph node from 1995, using techniques not previously available, resulted in a revised diagnosis of composite lymphoma, comprising both follicular lymphoma (FL) and small lymphocytic lymphoma (SLL). Analysis of B-cell gene rearrangement studies using BIOMED-2-based PCR, and of t(14;18) rearrangements by both FISH and PCR, provided evidence that the DLBCL evolved from transformation of the composite lymphoma, specifically from its FL component. B-cell gene rearrangement studies also supported a clonal relationship between the FL and SLL components of the composite lymphoma.

Chlamydial heat shock protein 60 induces acute pulmonary inflammation in mice via the Toll-like receptor 4- and MyD88-dependent pathway.

Heat shock protein 60 derived from Chlamydia pneumoniae (cHSP60) activates Toll-like receptor 4 (TLR4) signaling through the MyD88 pathway in vitro, but it is not known how cHSP60 contributes to C. pneumoniae-induced lung inflammation. We treated wild-type (WT), TLR2(-/-), TLR4(-/-), or MyD88(-/-) mice intratracheally (i.t.) with recombinant cHSP60 (50 microg), UV-killed C. pneumoniae (UVCP; 5 x 10(6) inclusion-forming units/mouse), lipopolysaccharide (2 microg), or phosphate-buffered saline (PBS) and sacrificed mice 24 h later. Bronchoalveolar lavage (BAL) was obtained to measure cell counts and cytokine levels, lungs were analyzed for histopathology, and lung homogenate chemokine concentrations were determined. Bone marrow-derived dendritic cells (BMDDCs) were generated and stimulated with live C. pneumoniae (multiplicity of infection [MOI], 5), UVCP (MOI, 5), or cHSP60 for 24 h, and the expression of costimulatory molecules (CD80 and CD86) was measured by fluorescence-activated cell sorting. cHSP60 induced acute lung inflammation with the same intensity as that of UVCP-induced inflammation in WT mice but not in TLR4(-/-) or MyD88(-/-) mice. cHSP60- and UVCP-induced lung inflammation was associated with increased numbers of cells in BAL, increased neutrophil recruitment, and elevated BAL interleukin-6 (IL-6) levels. Both cHSP60 and UVCP induced IL-6 release and CD80 and CD86 expression in WT cells but not in MyD88(-/-) BMDDCs. cHSP60 stimulated DC activation in a TLR4- and MyD88-dependent manner with an intensity similar to that induced by UVCP. These data suggest that cHSP60 promotes lung inflammation and DC activation via TLR4 and MyD88 and therefore may play a significant role in the pathogenesis of C. pneumoniae-induced chronic inflammatory lung diseases.

Innate immune responses during respiratory tract infection with a bacterial pathogen induce allergic airway sensitization.

BACKGROUND: The original hygiene hypothesis predicts that infections should protect against asthma but does not account for increasing evidence that certain infections might also promote asthma development. A mechanistic reconciliation of these findings has not yet emerged. In particular, the role of innate immunity in this context is unclear. OBJECTIVE: We sought to test whether bacterial respiratory tract infection causes airway sensitization toward an antigen encountered in parallel and to elucidate the contribution of innate immune responses. METHODS: Mice were infected with different doses of Chlamydia pneumoniae, followed by exposure to human serum albumin (HSA) and challenge with HSA 2 weeks later. Airway inflammation, immunoglobulins, and lymph node cytokines were assessed. Furthermore, adoptive transfer of dendritic cells (DCs) and depletion of regulatory T (Treg) cells was performed. RESULTS: C pneumoniae-induced lung inflammation triggered sensitization toward HSA, resulting in eosinophilic airway inflammation after HSA challenge. Airway sensitization depended on the severity and timing of infection: low-dose infection and antigen exposure within 5 days of infection induced allergic sensitization, whereas high-dose infection or antigen exposure 10 days after infection did not. Temporal and dose-related effects reflected DC activation and could be reproduced by means of adoptive transfer of HSA-pulsed lung DCs from infected mice. MyD88 deficiency in DCs abolished antigen sensitization, and depletion of Treg cells prolonged the time window in which sensitization could occur. CONCLUSIONS: We conclude that moderate, but not severe, pulmonary bacterial infection can induce allergic sensitization to inert inhaled antigens through a mechanism that requires MyD88-dependent DC activation and is controlled by Treg cells.

Rare t(1;11)(q23;p15) in therapy-related myelodysplastic syndrome evolving into acute myelomonocytic leukemia: a case report and review of the literature.

Balanced chromosome rearrangements are the hallmark of therapy-related leukemia that develops in patients treated with topoisomerase II inhibitors. Many of these rearrangements involve recurrent chromosomal sites and associated genes (11q23/MLL, 21q22.3/AML1, and 11p15/NUP98), which can interact with a variety of partner genes. One such rearrangement is the rare t(1;11)(q23;p15), which involves juxtaposition of the homeobox gene PMX1 (PRRX1) and NUP98. We report on an additional patient with t(1;11) who presented with myelodysplastic syndrome (MDS) subsequent to treatment for a pleomorphic liposarcoma. With time, the patient's disorder progressed to acute myelomonocytic leukemia with cytogenetic evidence of clonal evolution. To our knowledge, this is the first report of a patient presenting with a myelodysplastic syndrome with isolated t(1;11) (q23;p15), which evolved into therapy-related acute myeloid leukemia (t-AML). This patient is the third reported with this cytogenetic rearrangement and t-AML, and is compared with the other two reports of t(1;11)(q23;p15).

Posttransplantation lymphoproliferative disorder presenting as a unilateral leg mass 10 years after kidney transplantation.

Epstein-Barr virus (EBV)-associated lymphoproliferative disorder is a well-known complication of solid organ transplantation. The risk factors include type and degree of immunosuppression and EBV status of the donor and recipient before transplantation. The manifestations of posttransplantation lymphoproliferative disorders are myriad, from subtle findings such as tonsillar hypertrophy to fulminant manifestations such as hepatocellular failure and death. Here we report an unusual presentation of posttransplantation lymphoproliferative disorder as unilateral leg swelling in a 68-year-old man 10 years after kidney transplantation. The patient had detectable EBV-DNA by polymerase chain reaction in the peripheral blood and EBV messenger RNA by in situ hybridization in biopsy tissue. The patient's tumor did not respond to reductions in immunosuppressive medication, intravenous immunoglobulin, ganciclovir, and rituximab. Eventually the patient responded to CHOP (cyclophosphamide, Oncovin [vincristine, Eli Lilly, Indianapolis, IN], prednisone, and doxorubicin) therapy. He is currently 2 years posttreatment, with a serum creatinine of 0.8 mg/dL, on no immunosuppression.

Comparative immunohistochemical profile of hepatocellular carcinoma, cholangiocarcinoma, and metastatic adenocarcinoma.

Distinguishing hepatocellular carcinoma (HCC) from cholangiocarcinoma (CC) and metastatic adenocarcinoma (MA) involving the liver can be problematic, often requiring the use of immunohistochemistry to facilitate diagnosis. Hep Par 1, a monoclonal antibody with expression confined primarily to benign and malignant hepatocytes, has recently become commercially available. We evaluated Hep Par 1 along with other immunohistochemical markers used to differentiate HCC, CC, and MA, including AE1/AE3, CAM 5.2, B72.3, monoclonal carcinoembryonic antigen (mCEA), polyclonal CEA (pCEA), alpha-fetoprotein (AFP), factor XIIIa, inhibin, CD10, villin, MOC-31, cytokeratin (CK) 7, CK 19, and CK 20, to determine the markers most useful in differentiating these entities. Forty-two cases of HCC, 9 cases of CC, and 56 cases of MA (24 colon, 15 pancreas, 8 ovary, 5 breast, and 4 stomach) were studied. Hep Par 1 was sensitive and specific for HCC, with 38 of 42 (90%) cases staining positively, whereas reactivity was observed in only 8 of 56 (14%) MAs and 0 of 9 CCs. Though limited somewhat by poor sensitivity, a bile canalicular pattern of staining with pCEA, CD10, and villin was specific for HCC and was not observed in the other tumors. Lack of mCEA and MOC-31 immunoreactivity was also characteristic of HCCs. CK 19 positivity favored CC over HCC, but was not useful in differentiating CC from MA. Expression of AFP, although observed in only about one third of the cases, favored HCC over CC and MA. CK 7 and CK 20 were also useful in this differential diagnosis, particularly when dealing with MA of colonic origin. AE1/AE3, CAM 5.2, B72.3, inhibin, and factor XIIIa were noncontributory in differentiating these entities.

Determination of HER-2 status and chromosome 17 polysomy in breast carcinomas comparing HercepTest and PathVysion FISH assay.

We evaluated and compared 2 HER-2 tests (immunohistochemical analysis [HercepTest, DAKO, Carpinteria, CA] and fluorescence in situ hybridization [FISH]) and assessed chromosome 17 polysomy status in relation to these tests. HER-2 status was obtained in 690 cases. The rinse step in the HercepTest before and after addition of the visualization reagent was 2 minutes in 188 cases and was increased to 5 minutes in 600 cases. HercepTest with both rinse steps was performed on duplicate slides in 98 cases. Chromosome 17 ploidy status based on FISH results was determined in 687 cases. Weak overexpression (2+) of HER-2 protein was not due to gene amplification in a majority of cases (67/76 [88%]). A small subset of breast carcinomas (19/687 [2.8%]) strongly overexpressed (3+) HER-2 protein without gene amplification. The aneuploidy rate was similar in negative and 2+ cases (60/141 [42.5%] and 12/26 [46%]), compared with 86% (18/21) in 3+ cases. The incidence of polysomy 17 in 2+ nonamplified cases (3/67 [4%]) was similar to that seen in negative cases (5.5%), in contrast with 47% (9/19) of 3+ nonamplified cases. Adding a longer rinse step to the HercepTest converted a subset (3/10 [30%]) of weakly positive cases to negative cases. Weak overexpression of HER-2 protein in a majority of cases seems to represent an artifactual staining pattern. Chromosome 17 polysomy is a major factor in strong HER-2 protein overexpression in 3+ nonamplified cases.

Principles of analytic validation of immunohistochemical assays: Guideline from the College of American Pathologists Pathology and Laboratory Quality Center.

CONTEXT: Laboratories must validate all assays before they can be used to test patient specimens, but currently there are no evidence-based guidelines regarding validation of immunohistochemical assays. OBJECTIVE: To develop recommendations for initial analytic validation and revalidation of immunohistochemical assays. DESIGN: The College of American Pathologists Pathology and Laboratory Quality Center convened a panel of pathologists and histotechnologists with expertise in immunohistochemistry to develop validation recommendations. A systematic evidence review was conducted to address key questions. Electronic searches identified 1463 publications, of which 126 met inclusion criteria and were extracted. Individual publications were graded for quality, and the key question findings for strength of evidence. Recommendations were derived from strength of evidence, open comment feedback, and expert panel consensus. RESULTS: Fourteen guideline statements were established to help pathology laboratories comply with validation and revalidation requirements for immunohistochemical assays. CONCLUSIONS: Laboratories must document successful analytic validation of all immunohistochemical tests before applying to patient specimens. The parameters for cases included in validation sets, including number, expression levels, fixative and processing methods, should take into account intended use and should be sufficient to ensure that the test accurately measures the analyte of interest in specimens tested in that laboratory. Recommendations are also provided for confirming assay performance when there are changes in test methods, reagents, or equipment.

Chlamydia pneumoniae infection in mice induces chronic lung inflammation, iBALT formation, and fibrosis.

Chlamydia pneumoniae (CP) lung infection can induce chronic lung inflammation and is associated with not only acute asthma but also COPD exacerbations. However, in mouse models of CP infection, most studies have investigated specifically the acute phase of the infection and not the longer-term chronic changes in the lungs. We infected C57BL/6 mice with 5 × 10(5) CP intratracheally and monitored inflammation, cellular infiltrates and cytokine levels over time to investigate the chronic inflammatory lung changes. While bacteria numbers declined by day 28, macrophage numbers remained high through day 35. Immune cell clusters were detected as early as day 14 and persisted through day 35, and stained positive for B, T, and follicular dendritic cells, indicating these clusters were inducible bronchus associated lymphoid tissues (iBALTs). Classically activated inflammatory M1 macrophages were the predominant subtype early on while alternatively activated M2 macrophages increased later during infection. Adoptive transfer of M1 but not M2 macrophages intratracheally 1 week after infection resulted in greater lung inflammation, severe fibrosis, and increased numbers of iBALTS 35 days after infection. In summary, we show that CP lung infection in mice induces chronic inflammatory changes including iBALT formations as well as fibrosis. These observations suggest that the M1 macrophages, which are part of the normal response to clear acute C. pneumoniae lung infection, result in an enhanced acute response when present in excess numbers, with greater inflammation, tissue injury, and severe fibrosis.

Immunohistochemical profile to distinguish urothelial from squamous differentiation in carcinomas of urothelial tract.

Urothelial neoplasms with squamous morphology raise the differential diagnosis between pure primary squamous cell carcinoma, urothelial carcinoma with squamous differentiation and secondary involvement by squamous cell carcinoma, for example, from uterine cervix. Accurate identification between these entities is critical due to differing prognosis and therapeutic strategies. We evaluated the utility of an immunohistochemical panel of 3 urothelial-associated antibodies (uroplakin III, S100P, and GATA3) and two squamous-associated antibodies (CK14 and desmoglein-3) in 50 primary urothelial neoplasms: 15 pure urothelial carcinomas, 12 pure squamous cell carcinomas and 23 urothelial carcinomas with squamous differentiation. Squamous differentiation was defined by intercellular bridges or evidence of keratinization. Pure squamous cell carcinomas were positive for CK14 (100%) and desmoglein-3 (75%), negative for GATA3 and uroplakin III; one case was S100P positive (9%). Pure urothelial carcinomas had an opposite pattern and were positive for S100P (93%), GATA3 (93%), and uroplakin III (67%) and were negative for desmoglein-3; CK 14 was positive in 27% of cases; 74% of urothelial carcinomas with squamous differentiation had expression of urothelial and squamous associated markers (S100P, 83%; GATA3, 35%; uroplakin III, 13%; CK14, 87%; and desmoglein-3, 70%), although reactivity for individual markers within some tumors did not always correspond with morphologic differentiation. Of the remaining 26%, 4 showed an overall "squamous" immunoprofile, whereas 2 cases showed a "urothelial" immunoprofile. Our study showed that a panel of five antibodies identifies squamous and urothelial differentiation in most instances suggesting potential diagnostic utility.

Plasmacytoid dendritic cells play a role for effective innate immune responses during Chlamydia pneumoniae infection in mice.

Plasmacytoid dendritic cells (pDCs) are known for their robust antiviral response and their pro-tolerance effects towards allergic diseases and tissue engraftments. However, little is known about the role pDCs may play during a bacterial infection, including pulmonary Chlamydia pneumoniae (CP). In this study, we investigated the role of pDCs during pulmonary CP infection. Our results revealed that depletion of pDCs during acute CP infection in mice results in delayed and reduced lung inflammation, with an early delay in cellular recruitment and significant reduction in early cytokine production in the lungs. This was followed by impaired and delayed bacterial clearance from the lungs which then resulted in a severe and prolonged chronic inflammation and iBALT like structures containing large numbers of B and T cells in these animals. We also observed that increasing the pDC numbers in the lung by FLT3L treatment experimentally results in greater lung inflammation during acute CP infection. In contrast to these results, restimulation of T-cells in the draining lymph nodes of pDC-depleted mice induced greater amounts of proinflammatory cytokines than we observed in control mice. These results suggest that pDCs in the lung may provide critical proinflammatory innate immune responses in response to CP infection, but are suppressive towards adaptive immune responses in the lymph node. Thus pDCs in the lung and the draining lymph node appear to have different roles and phenotypes during acute CP infection and may play a role in host immune responses.

Chlamydia pneumoniae infection induced allergic airway sensitization is controlled by regulatory T-cells and plasmacytoid dendritic cells.

Chlamydia pneumoniae (CP) is associated with induction and exacerbation of asthma. CP infection can induce allergic airway sensitization in mice in a dose- and time-dependent manner. Allergen exposure 5 days after a low dose (mild-moderate), but not a high dose (severe) CP infection induces antigen sensitization in mice. Innate immune signals play a critical role in controlling CP infection induced allergic airway sensitization, however these mechanisms have not been fully elucidated. Wild-type, TLR2-/-, and TLR4-/- mice were infected intranasally (i.n.) with a low dose of CP, followed by i.n. exposure to human serum albumin (HSA) and challenged with HSA 2 weeks later. Airway inflammation, immunoglobulins, eosinophils, and goblet cells were measured. Low dose CP infection induced allergic sensitization in TLR2-/- mice, but not in TLR4-/- mice, due to differential Treg responses in these genotypes. TLR2-/- mice had reduced numbers of Tregs in the lung during CP infection while TLR4-/- mice had increased numbers. High dose CP infection resulted in an increase in Tregs and pDCs in lungs, which prevented antigen sensitization in WT mice. Depletion of Tregs or pDCs resulted in allergic airway sensitization. We conclude that Tregs and pDCs are critical determinants regulating CP infection-induced allergic sensitization. Furthermore, TLR2 and TLR4 signaling during CP infection may play a regulatory role through the modulation of Tregs.

Diagnostic implications of transcription factor Pax 2 protein and transmembrane enzyme complex carbonic anhydrase IX immunoreactivity in adult renal epithelial neoplasms.

Pax 2, expressed by metanephric mesenchyme is vital for renal tubule formation and development. Carbonic anhydrase IX (CA IX) is implicated in cell proliferation, adhesion, and invasion. Data regarding expression in renal epithelial tumors other than clear cell renal cell carcinoma (RCC) are limited, conflicting, from tissue microarrays, and do not encompass the entire spectrum or novel uncommon variants. Conventional sections from 200 renal tumors comprising clear cell RCC (n=30), oncocytoma (n=17), papillary RCC (n=30), chromophobe RCC (n=50), urothelial carcinomas (n=30), collecting duct carcinomas (n=5), renal tumors with Xp11.2 translocation (n=15), tubulocystic carcinoma (n=19), and mucinous tubular spindle cell carcinoma (n=4) were immunostained for Pax 2 and CA IX. Clear cell RCC (28/30, 93%), oncocytoma (17/17, 100%), papillary RCC (16/30, 53%), and mucinous tubular spindle cell carcinoma (3/4, 75%) demonstrated nuclear immunoreactivity with Pax 2, whereas the other subtypes were nonreactive. Clear cell RCC (30/30, 100%), urothelial carcinoma (27/30, 90%), papillary RCC (17/30, 57%), and renal tumors with Xp11.2 translocation (6/15, 40%) exhibited membranous immunoreactivity with CA IX, whereas the other subtypes were nonreactive. This suggests potential diagnostic utility of Pax 2 in distinction of (i) oncocytoma (positive) from chromophobe RCC (negative), (ii) clear cell RCC and papillary RCC (positive) from renal tumors with Xp11.2 translocation (negative), and (iii) high-grade clear cell RCC (positive) from urothelial carcinoma (negative). CA IX expression has potential diagnostic implications including (i) clear cell RCC (positive) versus chromophobe RCC (negative) and (ii) urothelial carcinoma (positive) versus collecting duct carcinoma (negative). These antibodies may reliably discriminate between clinically significant subtypes of RCC with overlapping cytoarchitectural features.

Utility of a comprehensive immunohistochemical panel in the differential diagnosis of spindle cell lesions of the urinary bladder.

Spindle cell lesions of the urinary bladder are uncommon, but when encountered in clinical practice, pose a difficult diagnostic challenge as the differential diagnostic considerations are vast. Pseudosarcomatous processes significantly overlap with malignant tumors (sarcomatoid urothelial carcinoma and leiomyosarcoma) in their morphology and published immunohistochemical profile [pancytokeratin pan (CK), smooth muscle actin (SMA), and desmin]. p63 has been studied rarely and CK 5/6 and CK 34betaE12 have not been analyzed in the bladder in this diagnostic context. In the current study, 45 typical examples of spindle cell lesions [10 pseudosarcomatous myofibroblastic proliferations (PMP), 22 sarcomatoid urothelial carcinomas, and 13 smooth muscle tumors] of the urinary bladder were immunostained with a panel containing broad spectrum anticytokeratin antibodies (OSCAR or AE1/AE3), as well as antibodies to CK 34betaE12, CK 5/6, p63, SMA, and anaplastic lymphoma kinase (ALK). The immunoreactivity was as follows: PMP-CK (OSCAR) 7/10 (70%), CK (AE1/AE3) 7/9 (78%), CK 34betaE12 0/10 (0%), CK 5/6 0/9 (0%), p63 0/9 (0%), SMA 10/10 (100%), ALK 2/10 (20%); sarcomatoid urothelial carcinoma-CK (OSCAR) 15/22 (68%), CK (AE1/AE3) 14/20 (70%), CK 34betaE12 5/20 (25%), CK5/6 6/22 (27%), p63 11/22 (50%), SMA 16/22 (73%), ALK 0/22 (0%); and smooth muscle tumors-CK (OSCAR) 7/13 (54%), CK (AE1/AE3) 7/12 (58%), CK 34betaE12 0/12 (0%), CK 5/6 0/12 (0%), p63 3/13 (23%), SMA 11/13 (85%), ALK 0/13 (0%). Positivity for keratin was typically focal to moderate in smooth muscle tumors and more commonly moderate to diffuse in sarcomatoid carcinomas and PMP. Our data indicate that there is significant immunohistochemical overlap between the different spindle cell lesions, each of which has unique clinicopathologic, prognostic, and therapeutic ramifications. Within the context of morphology, an immunohistochemical panel composed of broad-spectrum antibodies to cytokeratin as well as antibodies to SMA, ALK, p63, and CK 5/6 will be a useful diagnostic adjunct: a combination of pankeratin, SMA, and ALK positivity favors PMP; expression of several cytokeratin and especially CK 34betaE12 and CK 5/6 with p63 favors sarcomatoid carcinoma and SMA positivity with overall absence of other markers favors leiomyosarcoma.