Cutaneous intravascular natural killer/T cell lymphoma with peculiar immunophenotype.

Intravascular lymphoma (IVL) is a rare entity. Most cases are a variant of extranodal diffuse large B cell lymphoma, and fewer than 10% of the published cases are of T cell origin. Only intravascular B cell lymphoma is recognized as a distinct entity in the most recent World Health Organization (WHO) classification of lymphoproliferative disorders. We describe a case of cutaneous natural killer (NK)/T IVL, with a cytotoxic immunophenotype and Epstein-Barr virus (EBV) positivity. However, our case was immunohistochemically negative not only for T cell receptor (TCR)-ßF1 and TCR-γ (TCR-silent), but also for CD56, making it the first triple-negative NK/T IVL case to be described. We urge recognition of this NK/T cell lineage intravascular lymphoma due to its particular immunophenotypical profile and its unvarying relationship with EBV. Its occurrence should not be considered a coincidence, but rather a key aspect of the pathogenic background of this haematological neoplasm.

Focal adhesion kinase: predictor of tumour response and risk factor for recurrence after neoadjuvant chemoradiation in rectal cancer.

Rectal cancer represents about 30% of colorectal cancers, being around 50% locally advanced at presentation. Chemoradiation (CRT) followed by total mesorectal excision is the standard of care for these locally advanced stages. However, it is not free of adverse effects and toxicity and the complete pathologic response rate is between 10% and 30%. This makes it extremely important to define factors that can predict response to this therapy. Focal adhesion kinase (FAK) expression has been correlated with worse prognosis in several tumours and its possible involvement in cancer radio- and chemosensitivity has been suggested; however, its role in rectal cancer has not been analysed yet. To analyse the association of FAK expression with tumour response to CRT in locally advanced rectal cancer. This study includes 73 patients with locally advanced rectal cancer receiving standard neoadjuvant CRT followed by total mesorectal excision. Focal adhesion kinase protein levels were immunohistochemically analysed in the pre-treatment biopsies of these patients and correlated with tumour response to CRT and patients survival. Low FAK expression was significantly correlated with local and distant recurrence (P = 0.013). Low FAK expression was found to be a predictive marker of tumour response to neoadjuvant therapy (P = 0.007) and patients whose tumours did not express FAK showed a strong association with lower disease-free survival (P = 0.01). Focal adhesion kinase expression predicts neoadjuvant CRT response in rectal cancer patients and it is a clinically relevant risk factor for local and distant recurrence.

Molecular mediators of favism-induced acute kidney injury.

Intolerance to fava beans in subjects with glucose-6-phosphate-dehydrogenase deficiency (favism) may lead to severe hemolytic crises and decreased renal function. Renal biopsy findings exploring the molecular mechanisms of renal damage in favism have not been previously reported. We report a case of favism-associated acute kidney injury in which renal biopsy showed acute tubular necrosis and massive iron deposits in tubular cells. Interestingly, iron deposit areas were characterized by the presence of oxidative stress markers (NADPH-p22 phox and heme-oxigenase-1) and macrophages expressing the hemoglobin scavenger receptor CD163. In addition, iron deposits, NADPH-p22 phox, hemeoxigenase- 1 and CD163 positive cells were observed in some glomeruli. These results identify both glomerular and tubular involvement in favism-associated acute kidney injury and suggest novel therapeutic targets to prevent or accelerate recovery from acute kidney injury.

Oxidative stress, macrophage infiltration and CD163 expression are determinants of long-term renal outcome in macrohematuria-induced acute kidney injury of IgA nephropathy.

BACKGROUND: Macroscopic hematuria (MH) may cause acute kidney injury (AKI) in IgA nephropathy. Up to 25% of patients with MH-associated AKI do not recover baseline renal function. Our objective was to identify subjects at high risk for an adverse renal function. METHODS: We examined macrophages, oxidative stress markers (NADPH-p22 and HO-1) and the hemoglobin scavenger receptor (CD163) in renal biopsy specimens from 33 MH-AKI patients with complete recovery (CR, n = 17) or incomplete recovery (IR, n = 16) of renal function after 6.72 (range 0.5-21.5) years of follow-up. RESULTS: CD163-expressing macrophages, HO-1 and NADPH-p22 expression were located in areas surrounding tubules with iron deposits and filled with erythrocyte casts. CD163-positive macrophages score and HO-1- and p22-positive staining correlated positively with percentage of tubules with erythrocyte casts and tubular necrosis. Macrophage infiltration, CD163-positive macrophage score, NADPH-p22- and HO-1-positive staining areas were significantly greater in IR patients when compared with CR patients. The CD163-positive macrophage score and oxidative stress markers (p22 and HO-1) were negatively correlated with renal function outcome, as determined by estimated glomerular filtration rate (eGFR) and proteinuria, at the end of the follow-up period. In multivariate analysis, the CD163-positive macrophage score remained significantly associated with final eGFR and proteinuria after adjustment by age, gender, duration of MH, initial eGFR and proteinuria. CONCLUSIONS: Increased macrophage infiltration, CD163 expression and oxidative stress are significant prognostic factors for an IR of renal function in patients with MH-associated AKI. These molecular pathways may be involved in the renal response to injury and could be useful to improve diagnosis and therapeutics.

Ciliated hepatic foregut cyst: two further cases with an immunohistochemical analysis.

The objective of the present study is to report two cases of a rare entity, which is being increasingly recognized in recent years. A 35-year-old woman and a 33-year old man were incidentally discovered to have bilocular cystic hepatic masses affecting segment IV. In both cases the cystic mass was excised and the histopathological analysis revealed an inner lining of the cyst wall with a pseudostratified epithelium showing prominent cilia. The cyst wall contained some muscular fibers but no cartilage or other tissue types and diagnosis was ciliated hepatic cyst. Both patients recovered uneventfully after surgery and are well and disease free. Ciliated hepatic cysts are rare cystic hepatic masses derived from remnants of the embryonal foregut that are embedded inside the hepatic bud during embryological development. Fewer than 100 cases of this tumor have been reported in the world literature, many of them in Japan, and most cases have behaved in a benign fashion, although there are at least three reported cases of malignancy within the cyst wall to a squamous cell carcinoma. We herein report two further cases of this entity, highlight the diagnostic usefulness of immunohistochemistry and comment on the possible therapeutic alternatives.

Acute renal failure associated to paroxysmal nocturnal haemoglobinuria leads to intratubular haemosiderin accumulation and CD163 expression.

Decreased renal function has been observed in diseases with intravascular haemolysis, including paroxysmal nocturnal haemoglobinuria (PNH). However, the mechanisms via which haemoglobin enhances renal damage in this pathology are not fully known. We report a case of acute renal failure associated to PNH and extensive haemosiderin deposits in tubular cells. Renal biopsy also revealed a strong immunostaining of CD163 (a haemoglobin scavenger receptor expressed in macrophages) and oxidative stress markers (NADPH-p22 phox and haeme oxigenase-1) in areas with deposits of iron. This fact provides evidence for a pathogenic role for free haemoglobin in tubulointerstitial renal injury in human PNH disease.

Lichen scrofulosorum mimicking lichen planus.

Lichen scrofulosorum is the most uncommon clinicopathologic variant of the tuberculids. Usually, the eruption appears in children and adolescents with strong immune sensitivity to Mycobacterium tuberculosis and consists of tiny follicular papules, closely resembling lichen nitidus. We report a case of lichen scrofulosorum in an adult male with active cervical scrofuloderma who developed lesions of lichen scrofulosorum mimicking clinically lichen planus. Histopathologic study demonstrated granulomas around the hair follicles, although acid-fast bacilli stains, immunohistochemical stain for mycobacteria, polymerase chain reaction investigations and cultures failed to demonstrate Mycobacterium tuberculosis in the cutaneous lesions. The most striking features of the reported case were the onset of the eruption in an adult patient and the clinical appearance of the lesions, resembling lichen planus.

Inhibition of JAK2 protects renal endothelial and epithelial cells from oxidative stress and cyclosporin A toxicity.

Cyclosporin A is an immunosuppressant drug widely used in solid organ transplantation, but it has nephrotoxic properties that promote oxidative stress. The JAK2/STAT pathway has been implicated in both cell protection and cell injury; therefore, we determined a role of JAK2 in oxidative stress-mediated renal cell injury using pathophysiologically relevant oxidative challenges. The AG490 JAK2 inhibitor and overexpression of a dominant negative JAK2 protein protected endothelial and renal epithelial cells in culture against peroxide, superoxide anion and cyclosporin A induced cell death while reducing intracellular oxidation in cells challenged with peroxide and cyclosporin A. The decrease in Bcl2 expression and caspase 3 activation, induced by oxidative stress, was prevented by AG490. In mouse models of ischemia/reperfusion and cyclosporin A nephrotoxicity, AG490 decreased peritubular capillary and tubular cell injury. Our study shows that JAK2 inhibition is a promising renoprotective strategy defending endothelial and tubular cells from cyclosporin A- and oxidative stress-induced death.

Cutaneous composite hemangioendothelioma with satellitosis and lymph node metastases.

The term hemangioendothelioma has been used in recent years to name a heterogeneous group of vascular neoplasms, intermediate in both biological behavior and histopathologic appearance between benign tumors (hemangiomas) and frankly malignant tumors (angiosarcomas). Thus, within the spectrum of hemangioendothelioma have been successively included epithelioid hemangioendothelioma, spindle cell hemangioendothelioma, retiform hemangioendothelioma, kaposiform hemangioendothelioma, polymorphous hemagioendothelioma of the lymph nodes, papillary intralymphatic angioendothelioma (PILA) and composite hemangioendothelioma. The latter is a vascular neoplasm showing varying combinations of benign, low-grade malignant and malignant vascular components. We herein report a case of composite hemangioendothelioma showing a combination of retiform hemangioendothelioma, epithelioid hemangioendothelioma, spindle cell hemangioma and PILA. The neoplasm showed a more aggressive behavior than other reported cases of composite hemangioendothelioma and it developed satellitosis and metastases to the inguinal lymph nodes. Neoplastic cells expressed immunoreactivity for Prox-1, supporting a lymphatic line of differentiation.

Multicystic/cavitated giant left atrial myxomas: a matter of technology?

We present the case of a rare echocardiographic image of a giant cavitated myxoma and the pathologic findings of the cystic mass. The new echocardiographic equipment not only has improved the sensitivity for diagnosis of different pathologies but also has redefined its visual and morphologic characteristics. Although most myxomas are solid masses and some cystic myxomas have been reported, the presence of multiple cavities on echocardiographic exam has exceptionally been described. While cystic changes have been described at autopsy in 14% of cardiac myxomas, its identification with echocardiography is rare. Nowadays, the new echocardiographic equipment has improved the quality and the accuracy to detect and describe intracardiac masses, showing myxomas with cystic cavities in vivo that in the past was a pathologic finding.

Targeted therapies in breast cancer.

Overexpression, activation, and dysregulation of various membrane receptors, signaling pathways, and other factors occur frequently in human breast cancer. Therapeutic approaches targeting these molecules and the selective estrogen receptor modulators and aromatase inhibitors have been demonstrated to have higher efficacy than conventional therapy agents in the treatment of breast cancer, and to have an extensive potential. A rapid expansion of novel diagnostics and predictive tests designed to select the best target population and to personalize cancer care is occurring, but there remain several significant needs for improving the accuracy and reliability of these tests. The use of unstandardized methods and a widespread concern that inaccuracy in interpretation of assays is leading to an unacceptably high error rate in determining the true status of a potential predictive marker in current clinical practice. A variety of factors, including preanalytic conditions, slide-scoring procedures, and other variables, that may be contributing to current testing error rates must be improved for the standardization of these assay procedures to further enable the highest possible quality of diagnoses for breast cancer patients.

Immunohistochemical analysis of low-grade and high-grade prostate carcinoma: relative changes of parathyroid hormone-related protein and its parathyroid hormone 1 receptor, osteoprotegerin and receptor activator of nuclear factor-kB ligand.

AIM: To investigate multiple bone cytokines produced by prostate carcinoma (PCa) as a novel strategy to differentiate potential aggressiveness in localised PCa using immunohistochemical analysis. METHODS: A total of 47 cases of PCa undergoing radical prostatectomy or transurethral prostatic resection at our institution (Fundación Jiménez Díaz (Grupo Capio), Madrid, Spain) between January 1991 and June 1998 were identified as low-grade (< or =4; n = 22) or high-grade (> or =7, excluding 7 (3+4) cases; n = 25) PCa according to Gleason grade. PCa specimens were immunostained for: parathyroid hormone (PTH)-related protein (PTHrP), the PTH1 receptor, osteoprotegerin and receptor activator of nuclear factor-kappa B ligand (RANKL), as well as Ki67 (a proliferation marker) and CD34 (an angiogenesis marker). RESULTS: PCa samples showed an increased immunostaining for both osteoprotegerin and RANKL, associated with tumour grade and PTHrP positivity, in the tumoral epithelium. Using a score value of 4-corresponding to moderate staining - as cut-off, the best sensitivity value was for PTHrP (with C-terminal antiserum C6; 100 %); wheras the best specificity value was for RANKL (95 %). CONCLUSIONS: All the evaluated factors are overexpressed mainly in the high-grade tumours. Our findings indicate that, in most patients with PCa (with Ki67 values between 1% and 9%), sequential determination of C-terminal PTHrP and RANKL immunoreactivities is a useful approach to discriminate low-grade and high-grade tumours.

Long-term organ protection by doxazosin and/or quinapril as antihypertensive therapy.

BACKGROUND: Even with optimal blood pressure control, organ protection may also depend on the selected therapeutic regime. Angiotensin-converting enzyme inhibitors have been shown to provide excellent organ protection in hypertension, and may show dose-dependent protective effects. Adrenergic alpha blockers have been associated with an increased rate of heart failure in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) and Vasodilator-Heart Failure Trial (V-HeFT). This has been related to a proapoptotic effect of this drug in cardiomyocytes. Our purpose is to compare the heart and renal protection of a high quinapril dose, with a combined low quinapril dose plus doxazosin, in an animal model of chronic hypertension. METHODS: Uninephrectomized spontaneously hypertensive 12-week-old rats were treated for 36 weeks with either quinapril or a combination of doxazosin plus a low quinapril dose. Tight blood pressure control was achieved with both treatments. Renal and cardiac protection was assessed by different parameters, and cardiac apoptosis was evaluated by active caspase-3, apoptotic protein and heat shock protein levels. Untreated hypertensive and normotensive rats were included as controls. RESULTS: Both treatments showed significant heart and renal protection compared with untreated animals. Both therapeutic regimes showed similar protection in renal and cardiac pathology, coronary media fibrosis, myocardial apoptosis and cardiac index. Proteinuria and left ventricular hypertrophy regression were significantly lower in the quinapril group compared with the combined treatment group. CONCLUSIONS: Blood pressure control with a high quinapril dose provided higher organ protection than a combined therapy with a lower quinapril dose. This effect was not due to a deleterious effect of doxazosin.

Regional lymphomatoid papulosis of the breast restricted to an area of prior radiotherapy.

We report the case of a 59-year-old woman with type A regional lymphomatoid papulosis (LyP) that was localized to the left breast, a cutaneous area that had received radiotherapy for treatment of a carcinoma of the breast 5 years prior. This report is a rare example of regional LyP with all lesions located in an area of prior radiotherapy.

Decreased PLK1 expression denotes therapy resistance and unfavourable disease-free survival in rectal cancer patients receiving neoadjuvant chemoradiotherapy.

AIM: Polo-like kinase 1 (Plk1) plays a key role in mitotic cell division and DNA damage repair. It has been observed that either up-regulated or down-regulated Plk1 could induce mitotic defects that results in aneuploidy and tumorigenesis, probably depending on the context. Few previous reports have associated Plk1 expression with prognosis and response to radiotherapy in rectal carcinomas. The aim of this study is to investigate the prognostic impact of Plk1 expression and its role in predicting response to neoadjuvant cheomoradiotherapy in rectal cancer. METHODS AND RESULTS: Immunohistochemical analysis of Plk1 expression was performed in the pre-treatment tumour specimens from 75 rectal cancer patients. We analysed the assocation between Plk1 expression and clinicopathological parameters, pathologic response and outcome. Opposed to previous reports on this issue, low expression of Plk1 was significantly associated with a high grade of differentiation (P=0.0007) and higher rate of distant metastasis (P=0.014). More importantly, decreased levels of Plk1 were associated with absence of response after neoadjuvant therapy (P=0.049). Moreover, low Plk1 expression emerged as an unfavourable prognostic factor for disease-free survival in the non-responder group of patients (P=0.037). CONCLUSIONS: Decreased Plk1 expression was associated with poor pathologic response and worse disease-free survival in rectal cancer patients receiving neoadjuvant chemoradiotherapy, suggesting Plk1 as a clinically relevant marker to predict chemoradiotherapy response and outcome.

Increased prevalence of p53 overexpression from typical endometriosis to atypical endometriosis and ovarian cancer associated with endometriosis.

OBJECTIVE: To evaluate the expression of p53, c-erb-B-2, MIB1 and Bcl-2 in normal endometrium, endometriosis, atypical endometriosis and ovarian cancer associated with endometriosis, looking for immunohistochemical markers that may help determine endometriosis with premalignant potential. STUDY DESIGN: Between 1948 and 1999, 410 epithelial ovarian cancers and 521 cases of endometriosis were surgically treated at Fundación Jiménez Díaz. Pathology reports and slides were reviewed. Four groups were defined: (1) endometriosis/cancer (n=17); (2) atypical endometriosis (n=6); (3) endometriosis (n=17); (4) endometrium (n=7). Tumors and controls were immunostained and evaluated for expression of p53, c-erb-B-2, MIB1 and Bcl-2. Statistical analysis was performed using Chi-square for linear trends, Fisher exact and Kruskal-Wallis tests. RESULTS: Of the 410 cancers, 17 (4.1%) had associated endometriosis and of the 521 endometriosis, 6 (1.2 %) had atypical changes. Fourteen of 17 (82.4%) cancers associated with endometriosis and all atypical endometriosis had p53 overexpression. Only 2 of 17 (11.8%) endometriosis and none of the endometriums had mutant p53 (P<0.01). We found a trend towards increased expression of MIB1 (0.073) in the cancer and atypical endometriosis groups, and no differences in expression of Bcl-2 or c-erb-B-2. The sensitivity and specificity of p53 as a marker for the diagnosis of atypical endometriosis and cancer associated with endometriosis were 87%; CI 95% (73.2-100%) and 92% (80.6-100%), respectively. When comparing all groups, the mean positive p53 and MIB1 cell count was statistically significant (P=0.01). CONCLUSIONS: Overexpression of p53 in atypical endometriosis and cancer associated with endometriosis is a common finding and may be used to identify endometriosis with premalignant potential.

Infective endocarditis at autopsy: a review of pathologic manifestations and clinical correlates.

The frequency of autopsies appears to be declining, and the usefulness has been challenged. We reviewed cases of autopsied active infective endocarditis (IE) during 2 periods based on the availability of high-tech 2-dimensional echocardiograms: Period 1 (P1) included 40 cases studied from 1970 to 1985, and Period 2 (P2) included 28 cases seen from 1986 to 2008--that is, before and after the introduction of echocardiograms in our institution. We conducted the study to reassess the pathology of IE and to determine how frequently diagnosis is not made during life.The age of patients increased 10 years on average between the 2 periods, and comorbidities were significantly more frequent in P2. While the frequency of rheumatic valve disease and prosthetic valve endocarditis (PVE) decreased, degenerative valve disease increased. Isolated mitral or aortic valve IE was most common. Right-sided IE was observed in patients with Staphylococcus aureus bacteremia from infected venous lines. In most cases IE involved only the cusps of cardiac valves. "Virulent" microorganisms caused ulcerations, rupture, and perforation of the cusps and necrosis of chordae tendiniae and perivalvular apparatus. In PVE the lesions were located behind the site of attachment, and vegetations were seen on the sewing ring in both metallic and biologic prostheses. Infection spread to adjacent structures and myocardium with ring abscess observed in 88% of cases. Prosthetic detachment causing valve regurgitation was associated with abscesses in 76% of cases; these patients developed persistent sepsis and severe cardiac failure. Obstruction occurred in patients with PVE of the mitral valve. Acute purulent pericarditis was observed in 22% of cases, mainly in patients with aortic valve IE and myocardial abscesses.Gross infarcts were seen in 63% of cases but were asymptomatic in most instances. The spleen, kidneys, and mesentery were the sites most frequently involved. Myocardial infarctions were found in less than 10% of cases. Abscesses were also frequently found and were a common source of persistent fever and bacteremia. Glomerulonephritis was more common in the first period. Brain pathology consisted of ischemic and hemorrhagic infarcts and abscesses. Cerebral bleeding was more frequent in patients with PVE on anticoagulant therapy. Neutrophilic meningitis was observed in S. aureus IE.Diagnosis of IE was not made during life in 14 (35%) cases during P1 and 12 (42.8%) cases in P2. Overall, diagnosis was missed until autopsy in 38.2% of cases. IE was hospital acquired in 28 instances. While a clinical diagnosis was made in all but 4 cases of early-onset PVE (23.5%), the diagnosis was not made during life in 22 of 51 patients with native-valve IE (43.1%). Of these 22 patients, IE was hospital acquired in 11 (50%). The absence of fever, cardiac murmurs, and many of the typical stigmata of endocarditis may have led to the diagnosis being overlooked clinically.Brain bleeding, cardiac failure and less frequently acute myocardial infarct were the most common causes of death.IE continues to be missed frequently until autopsy. Postmortem examination is an important tool for evaluating the quality of care, and for guiding teaching and research related to cardiovascular infections.

Undetectable serum calcidiol: not everything that glitters is gold.

There is an increased awareness of the adverse consequences of nutritional vitamin D deficiency. We report a patient with chronic tophaceous gout, chronic kidney disease (CKD) Stage 3/4 and undetectable serum calcidiol who developed severe hypercalcaemia upon vitamin D supplementation despite serum 25(OH) vitamin D within the normal range. Upon recovery, serum 1,25(OH)2 vitamin D remained in the normal range despite CKD and serum 25(OH) vitamin D 6 ng/mL. Gout tophi biopsies from additional patients showed macrophage expression of 25(OH) vitamin D 1α-hydroxylase. This case illustrates the dangers of supplementing vitamin D in patients with low serum 25(OH) vitamin D and increased 1α-hydroxylase activity due to granulomatous disease.

Inflammatory cytokines and survival factors from serum modulate tweak-induced apoptosis in PC-3 prostate cancer cells.

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK, TNFSF12) is a member of the tumor necrosis factor superfamily. TWEAK activates the Fn14 receptor, and may regulate cell death, survival and proliferation in tumor cells. However, there is little information on the function and regulation of this system in prostate cancer. Fn14 expression and TWEAK actions were studied in two human prostate cancer cell lines, the androgen-independent PC-3 cell line and androgen-sensitive LNCaP cells. Additionally, the expression of Fn14 was analyzed in human biopsies of prostate cancer. Fn14 expression is increased in histological sections of human prostate adenocarcinoma. Both prostate cancer cell lines express constitutively Fn14, but, the androgen-independent cell line PC-3 showed higher levels of Fn14 that the LNCaP cells. Fn14 expression was up-regulated in PC-3 human prostate cancer cells in presence of inflammatory cytokines (TNFα/IFNγ) as well as in presence of bovine fetal serum. TWEAK induced apoptotic cell death in PC-3 cells, but not in LNCaP cells. Moreover, in PC-3 cells, co-stimulation with TNFα/IFNγ/TWEAK induced a higher rate of apoptosis. However, TWEAK or TWEAK/TNFα/IFNγ did not induce apoptosis in presence of bovine fetal serum. TWEAK induced cell death through activation of the Fn14 receptor. Apoptosis was associated with activation of caspase-3, release of mitochondrial cytochrome C and an increased Bax/BclxL ratio. TWEAK/Fn14 pathway activation promotes apoptosis in androgen-independent PC-3 cells under certain culture conditions. Further characterization of the therapeutic target potential of TWEAK/Fn14 for human prostate cancer is warranted.

Immunohistochemical profile of urothelial and small cell carcinomas of the bladder.

Small cell carcinoma of the bladder is an uncommon and rather aggressive bladder tumor, representing less than 1% of all vesical tumors. Small cell carcinoma of different organs has been shown to express markers of neuroendocrine differentiation, and also thyroid transcription factor 1 (TTF-1). TTF-1 is a transcription factor and its expression has been shown mainly in pulmonary small cell carcinomas and adenocarcinomas and in thyroid tumors. Although it was initially proposed as a useful marker to delineate the origin of metastatic adenocarcinomas from the lung, its expression is being increasingly reported in tumors from different origins. The goal of this review is to analyse the immunohistochemical profile of small cell carcinoma of the bladder and to compare it to classical urothelial cell carcinomas. With this aim we have reviewed the small cell bladder carcinomas diagnosed in a single tertiary hospital in Madrid (Fundación Jiménez Díaz) in the last 12 years. We have found 6 pure small cell carcinomas and performed a wide panel of immunohistochemistry, including cytokeratins 7 and 20, enolase, chromogranin, synaptophysin, CD56 and TTF-1 to these tumors and also to 30 high grade urothelial cell carcinomas of usual type. Only one of our small cell carcinoma cases showed positivity for TTF-1, while five expressed CD56 and four neuron-specific enolase. None of our cases expressed cytokeratin 20 or 7. To our surprise we found a case of conventional urothelial cell carcinoma expressing focally TTF-1. These results are in accordance with the current literature, although our rate of TTF-1 expression (16.6%) is on the low end of the spectrum.