Cytokeratin 20 expression is linked to stage progression and to poor prognosis in advanced (pT4) urothelial carcinoma of the bladder.

Cytokeratin 20 (CK20) expression is limited to umbrella cells in the normal urothelium. Since CK20 is often upregulated in neoplastic urothelial cells including dysplasia and carcinoma in situ, immunohistochemical CK20 analysis is often used for the assessment of bladder biopsies. CK20 expression is a feature of luminal bladder cancer subtype, but its prognostic relevance is disputed. In this study, we investigated CK20 on >2700 urothelial bladder carcinomas in a tissue microarray format by immunohistochemistry. Cytoplasmic and membranous CK20 staining was seen in 1319 (51.8%) cancers. The fraction of CK20 positive and especially strongly positive cases increased from pTaG2 low grade (44.5% strongly positive) and pTaG2 high grade (57.7%) to pTaG3 high grade (62.3%; p = 0.0006) but was lower in muscle-invasive (pT2-4) carcinomas (51.1% in all pTa vs. 29.6% in pT2-4; p < 0.0001). Within pT2-4 carcinomas, CK20 positivity was linked to nodal metastasis and lymphatic vessel invasion (p < 0.0001 each) and to venous invasion (p = 0.0177). CK20 staining was unrelated to overall patient survival if all 605 pT2-4 carcinomas were jointly analyzed but subgroup analyses revealed a significant association of CK20 positivity with favorable prognosis in 129 pT4 carcinomas (p = 0.0005). CK20 positivity was strongly linked to the expression of GATA3 (p < 0.0001), another feature of luminal bladder cancer. The combined analysis of both parameters showed best prognosis for luminal A (CK20+/GATA3+, CK20+/GATA3-) and worst outcome for luminal B (CK20-/GATA3+) and basal/squamous (CK20-/GATA3-) in pT4 urothelial carcinomas (p = 0.0005). In summary, the results of our study demonstrate a complex role of CK20 expression in urothelial neoplasms including neoexpression in pTa tumors, a subsequent loss of CK20 expression in a subset of tumors progressing to muscle-invasion, and a stage dependent prognostic role in muscle-invasive cancers.

A review of 14 cases of perianal Paget's disease: characteristics of anorectal cancer with pagetoid spread.

BACKGROUND: Perianal Paget's disease (PPD) is an intraepithelial invasion of the perianal skin and is frequently associated with underlying anorectal carcinoma. The relatively rare nature of this disease has made it difficult to develop treatment recommendations. This study aims to analyze the clinical and pathological features of perianal Paget's disease (PPD) and to explore rational treatment options and follow-up for this disease. METHODS: The National Cancer Center Hospital database was searched for all cases of perianal Paget's disease diagnosed between 2006 and 2021. In the 14 patients identified, we reviewed the diagnosis, management, and outcomes of adenocarcinoma with pagetoid spread, including suspected or recurrent cases. RESULTS: All 14 cases met the inclusion criteria. The median follow-up period after diagnosis was 4.5 (range, 0.1-13.0) years. Pagetoid spread before initial treatment was suspected in 12 cases (85.7%). Underlying rectal cancer was identified in 6 cases, and no primary tumor was detected in the other 6 cases. Seven patients had recurrent disease, with the median time to recurrence of 34.6 (range, 19.2-81.7) months. The time to the first relapse was 3 months, and that to the second relapse was 6 months. The overall 5-year survival rate was 90.0%. CONCLUSIONS: Endoscopic and radiologic evaluation, as well as immunohistologic examination, should be performed. is to differentiate PPD with and without underlying anorectal carcinoma. The time to first recurrence varies widely, and long-term and regular follow-up for more than 5 years is considered necessary for local recurrence and distant metastasis.

Eosinophilic solid and cystic renal cell carcinoma and renal cell carcinomas with TFEB alterations: a comparative study.

AIMS: Eosinophilic solid and cystic renal cell carcinoma (ESC RCC) is a recently described renal tumour entity with frequent cytokeratin (CK)20 positivity, commonly harbouring TSC mutations. In contrast, frequency of CK20 expression and presence of TSC mutations are unclear in TFEB-amplified RCC and TFEB-translocated RCC, which frequently express Melan A. Herein, we provide a comparative analysis of six ESC RCC with four TFEB-amplified/translocated RCC. METHODS AND RESULTS: We assessed the frequency of CK20 and Melan A expression by immunohistochemistry and of TSC mutations by next-generation sequencing. TFEB alterations were confirmed by fluorescence in-situ hybridisation (FISH). All tumours showed voluminous eosinophilic cells with granular cytoplasm, prominent nucleoli, and most showed admixture of solid and cystic areas. CK20 expression was found in all six ESC RCC and in all RCCs with TFEB alterations. Melan A positivity was identified in five of six ESC RCC and four of four RCC with TFEB alterations. We found TSC mutations in two ESC RCCs, including in one case also harbouring a CIC fusion, and identified a TSC mutation in one TFEB-amplified RCC. CONCLUSIONS: ESC RCC represents an emerging renal tumour entity with some histological, immunohistochemical and molecular overlap to TFEB-amplified/translocated RCC. FISH for TFEB aids in this differential diagnosis in challenging cases.

Cytokeratin 7 and cytokeratin 20 expression in cancer: A tissue microarray study on 15,424 cancers.

Combined analysis of cytokeratin 7 (CK7) and cytokeratin 20 (CK20) is often used for assessing the origin of metastatic cancer. To evaluate the diagnostic utility of CK7 and CK20, tissue microarrays containing 15,424 samples from 120 different tumor types and subtypes and 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry. CK7 positivity was seen in 52% (8.7% weak, 5.9% moderate, 37% strong) and CK20 positivity in 23% (5.1% weak, 3.4% moderate, 15% strong) of interpretable tumors. Of 8390 positive tumors, 1181 (14%) showed positivity for CK7 and CK20, 5380 (64%) showed positivity for CK7 alone, and 1829 (22%) showed positivity for CK20 alone. CK20 predominated in gastrointestinal tract, urothelial and Merkel cell carcinomas. CK7 was usually negative in prostate cancer and colorectal cancer. Combined evaluation of CK7/CK20 revealed the best diagnostic utility in CK20 positive tumors, where CK7 negativity is often linked to colorectal origin while CK7 positivity argues for urothelial origin or mucinous ovarian cancer. Associations with unfavorable tumor features were found for cytokeratin 7 loss in breast cancer of no special type, urothelial and renal cell carcinomas, for CK7 overexpression in high-grade serous ovarian and gastric cancer, and for CK20 overexpression in urothelial carcinoma. CK20 loss was linked to MSI in gastric (p = 0.0291) and colorectal adenocarcinoma (p < 0.0001). These analyses provide comprehensive data on the frequency of CK7 and CK20 immunostaining - alone or in combination - in human cancers. These data facilitate interpretation of CK7/CK20 immunostaining in cancers.

Merkel cell number and distribution, and CD200 expression in patients with lichen planopilaris and discoid lupus erythematosus.

BACKGROUND: Immune mechanisms are considered to be responsible for the pathogenesis of cicatricial alopecia in lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) diseases. CD200 has an immunomodulatory function in hair follicles. The functions of Merkel cells (MCs) in hair follicles remain to be fully understood. OBJECTIVE: This study aimed to determine the number and distribution of MCs as well as CD200 expression in patients with DLE and LPP. METHODS: Using immunohistochemistry, the number and distribution of MCs (staining with CK20) and CD200 expression in biopsy specimens of LPP and DLE patients were compared with control group patients. RESULTS: The number of follicular MCs, total MCs, mean follicular MCs, and CD200 expression were significantly lower in the case groups compared to the control group. In CD200- cases, the number of follicular MCs and mean follicular MCs were significantly lower than in CD200+ cases. Retrospective design, lack of data regarding the history of alopecia in the control group, and unknown stage of disease in patients were the limitations. CONCLUSION: MC loss might play a role in immune privilege collapse in hair follicles. This study is novel in terms of investigating MCs in DLE and LPP patients.

Fibroblast activation protein (FAP) expression in CK5/6 expressed (Basal subtype) & CK20 expressed (Luminal subtype) urothelial bladder carcinoma: an immunohistochemical study.

Urinary bladder cancer incidence varies all over the world. Egypt displays high incidence rates. Molecular subtyping helps risk stratification and personalized treatment. Cancer-associated fibroblasts (CAFs) in the tumor microenvironment may provoke tumor-promotion or tumor suppression. Fibroblast activation protein (FAP) is a marker of CAFs, suggested to accelerate tumor progression in various cancers. In urothelial carcinoma, investigations regarding impact of FAP expression on prognosis are needed. This work aims to study impact of FAP expression in urothelial carcinoma and find its relation to CK 5/6 (basal) expressed and CK 20 (luminal) expressed immunohistochemical markers. This retrospective study included 70 urothelial carcinoma specimens. Immunohistochemistry was performed and results were analyzed. FAP was expressed in 67.1% of cases and showed significant association with advanced tumor stage, muscle invasion, mitoses in tumor cells and stratified groups; as 73.9% of FAP positive cases were of Ck5/6+/Ck20- (basal subtype). All studied parameters did not show significant association with patient's overall survival. In conclusion, FAP could have a role in modulating tumor microenvironment and promoting tumor invasion. FAP is correlated with basal subtype of urothelial carcinoma, which may be an indicator of tumor aggressiveness. FAP antagonists may be helpful in preventing tumor progression.

Cytokeratin 5 and cytokeratin 20 inversely correlate with tumour grading in Ta non-muscle-invasive bladder cancer.

Cytokeratin 5 is a marker of basal molecular subtypes of muscle-invasive bladder cancer (MIBC), which correlates with worse overall survival compared to luminal subtypes. Our observations have not confirmed CK5 as a marker of high-grade (HG) disease in Ta non-muscle-invasive bladder cancer (NMIBC). Therefore, to understand the basal-luminal immunohistochemistry profile in Ta NMIBC, we performed immunohistochemistry for CK5, P40, P63 (basal), GATA3 and CK20 (luminal) and studied the correlation with HG and clinical outcome in 109 patients with Ta NMIBC. HG and low-grade (LG) diseases were scored in each patient. Four different CK5 patterns were evaluated: absent (median 41.3%), normal (72.5%), rising (84.4%) and full thickness (23.9%). The median percentage of GATA3 was 100%. HG disease and CK5 expression and rising CK5 pattern had a significant inverse correlation, whereas HG disease and CK20 expression had a significant positive correlation. We also found a significant inverse correlation between CK5 expression and CK20 expression. Quantitative PCR confirmed that the presence of CK5 correlated with up-regulation of CK5 RNA. None of the markers could differentiate patients with regard to clinical outcome. Our results suggest a role for CK5 and CK20 in differentiating between LG and HG disease in Ta NMIBC.

Stratification of urinary bladder carcinoma based on immunohistochemical expression of CK5, CK14 and CK20.

Molecular subtyping of urothelial carcinoma (UC) is similar to that of breast cancer and is based on the developmental biology approach. The aim of the present study is to assess the prognostic impact of CK5, CK14, and CK20 expression in urinary bladder cancer (UBC) with the potential to stratify them into different subtypes. The current study examined the immunohistochemical expression of CK5, CK14, and CK20 in 90 specimens of UBC. CK5 was expressed in 81.1% of the cases and was significantly associated with old age, muscle invasion, presence of bilharziasis, and tendency for poor overall survival. CK20 was expressed in 47.8% of the cases and was associated with nonmuscle invasion and pure UC while 50% of the cases expressed CK14 that were associated with muscle invasion and perineural invasion. Most squamous cell carcinoma and those associated with bilharziasis were belonged to Ck5+/CK20- subgroup while pure UC and those lacked bilharziasis were located in the Ck5+/CK20+ subgroup. The basal group (Ck5+/CK14+/CK20-) showed high proliferative features compared to the intermediate group (Ck5+/CK14-/CK20-). Generally, presence of CK5 is associated with adverse features especially in the group lacking CK20; however, basal and intermediate subgroups share CK5 expression but they show different proliferative capacities, so their distinction by CK14 is helpful.

Developmental histology of the portal plate in biliary atresia: observations and implications.

PURPOSE: The key characteristic of biliary atresia (BA) is obliteration of the extrahepatic bile ducts at the level of the porta hepatis. We aimed to relate the immunohistochemical features of remnant biliary ductules at the porta hepatis with clinical features and outcomes. METHODS: Samples were immunostained with anti-cytokeratin 20 (CK20), vimentin and alpha-smooth muscle actin (aSMA). Primary outcome was set as clearance of jaundice (bilirubin ≤ 20 µmol/L) following Kasai portoenterostomy (KPE). RESULTS: Eighty-two cases were classified into syndromic BA (n = 10), cystic BA (n = 7), CMV IgM+ BA (n = 9) and isolated BA (n = 56). CK20 expression was confirmed in 40/82 (49%), and vimentin expression in 19/82 (23%). aSMA was negative in all cases studied. CK20 expression was less common in isolated BA (n = 20/56, 36%) compared to CMV IgM+ BA (n = 8/9, 89%), cystic BA (n = 7/7, 100%) (isolated BA vs non-isolated BA, P = 0.0008). There was no difference in vimentin expression among the sub-groups (isolated BA vs. non-isolated BA; P = 0.39). CoJ was achieved in 52/82 (63%) overall with significant difference depending simply on sub-group [e.g. syndromic BA 9/10 (90%)]. CK20 expression was associated with a diminished rate of CoJ in the entire cohort [CK20+ 32/56 (57%) vs. CK20- 20/26 (77%); P = 0.04]. By contrast no correlation was observed between vimentin expression and CoJ (P = 0.13). CONCLUSION: CK20+ expression was associated with reduced clearance of jaundice in BA and a trend towards reduced native liver survival.

Triple collision tumor comprising Merkel cell carcinoma with an unusual immunophenotype, squamous cell carcinoma in situ, and basal cell carcinoma.

Merkel cell carcinoma (MCC) is a rare, aggressive primary cutaneous neuroendocrine cancer which almost always exhibits the cytokeratin (CK)20+/thyroid transcription factor (TTF)-1- immunophenotype. MCC may occur concurrently with squamous cell carcinoma, Bowen disease, and/or basal cell carcinoma (BCC), with some evidence that MCCs which occur in conjunction with other neoplasms exhibit different immunophenotypes compared to pure MCC cases. We present a case of CK20-/TTF-1+ MCC concurrent with Bowen disease and BCC, and discuss possible differences in the pathogenesis of pure vs combined MCC. We also review the literature for this unusual immunophenotype, noting that most cases occur in combined MCC.

Can flow cytometry reinvent the sentinel lymph node concept in gastric cancer patients?

BACKGROUND: The focused sentinel lymph node (SLN) concept we proposed previously relied on real time-quantitative polymerase chain reaction (RT-qPCR) to detect tumor cells, which is too elaborate for intraoperative use. Therefore, we evaluated flow cytometry for intraoperative detection of tumor cells in SLNs. METHODS: Sixty-five consecutive gastric cancer patients were included. SLN analysis was carried out for a single SLN from each patient, using the molecular methods of RT-qPCR (first 30 patients) and flow cytometry (final 35 patients). All LNs underwent hematoxylin and eosin staining and immunohistochemical examination. RESULTS: Extraction of the SLN from a high-risk station was an important determinant for accurate prediction of LN metastases. For RT-qPCR, the sensitivity and specificity of detection were 72.7% and 81.8%, respectively, and for flow cytometry, 36.8% and 100%, respectively. When only high-risk SLNs were analyzed and specimens with <10% viability of leukocytes were excluded, the sensitivity and specificity of flow cytometry were 60% and 100%, respectively. Multivariate analysis identified significant predictors for LN metastases as the molecular method of SLN analysis (P = 0.021; 95% confidence interval [CI]: 1.304-24.284) and lymphovascular invasion (P = 0.002; 95% CI: 2.142-28.555). In subgroup analysis of high-risk SLNs, only RT-qPCR was a significant predictor for LN metastases (P = 0.016; 95% CI: 1.581-91.084). CONCLUSIONS: Flow cytometry of high-risk SLNs, excluding specimens with low cell viability is a rapid, cost-effective, widely obtainable, and highly specific method for SLN metastases detection although it lacks the necessary sensitivity. Therefore, it cannot be recommended as a stand-alone method for the detection of LN metastases during operations.

Differentiating Merkel cell carcinoma of lymph nodes without a detectable primary skin tumor from other metastatic neuroendocrine carcinomas: The ELECTHIP criteria.

BACKGROUND: Merkel cell carcinoma (MCC) can present as a cutaneous tumor or a lymph node metastasis without a primary tumor. MCC presenting without a primary tumor (MCCWOPT) can be misinterpreted on histologic examination as lymph node metastasis (LNM) from another neuroendocrine carcinoma (LNMNEC). However, this distinction is crucial for therapeutic management. OBJECTIVE: To determine the discriminative criteria for the differential diagnosis of MCCWOPT, LNM from cutaneous MCC, and LNMNECs. METHODS: Clinical, morphologic, and immunohistochemical data (expression of cytokeratins AE1, AE3, 7, 19, and 20; chromogranin A, synaptophysin, thyroid transcription factor-1 [TTF-1]), as well as the presence of Merkel cell polyomavirus (by immunohistochemistry and PCR) were compared in patients with MCCWOPT (n = 17), LNM from a cutaneous MCC (n = 11), and LNMNEC (n = 20; 8 lung, 7 thyroid, 3 digestive tract, 2 other). RESULTS: MCC (including MCCWOPT and LNM from a cutaneous MCC) differed from LNMNEC by 7 discriminative criteria: 1) elderly age, 2) location of the tumor, 3) extent of the disease, 4) cytokeratin expression, 5) TTF-1 expression, 6) histologic type, and 7) Merkel cell polyomavirus detection, summarized under the acronym ELECTHIP. All MCC patients had ≥5 of the ELECTHIP criteria, whereas all patients with LNMNEC (except 1) had <3 criteria. LIMITATIONS: The discriminant ability of the ELECTHIP criteria should be validated in a second independent set. CONCLUSION: MCCWOPT can be distinguished from other LNMNEC by the ELECTHIP criteria.

Immunohistochemistry, carcinomas of unknown primary, and incidence rates.

Pathologists use immunohistochemistry is their day-to-day practices to assist in distinguishing site of origin of metastatic carcinomas. Here, the work-up is discussed neuroendocrine carcinomas, squamous cell carcinomas and adenocarcinomas with particular attention to tumor incident rates and predictive values of the best-performing immunohistochemical markers.

Detection of circulating tumor cells with CK20 RT-PCR is an independent negative prognostic marker in colon cancer patients - a prospective study.

BACKGROUND: Detection of circulating (CTC) or disseminated tumor cells (DTC) has been associated with negative prognosis and outcome in patients with colorectal cancer, though testing for these cells is not yet part of clinical routine. There are several different methodological approaches to detect tumor cells but standardized detection assays are not implemented so far. METHODS: In this prospective monocentric study 299 patients with colon cancer were included. CTC and DTC were detected using CK20 RT-PCR as well as immunocytochemistry staining with anti-pan-keratin and anti-EpCAM antibodies. The primary endpoints were: Evaluation of CTC and DTC at the time of surgery and correlation with main tumor characteristics and overall (OS) and disease free survival (DFS). RESULTS: Patients with detectable CTC had a 5-year OS rate of 68% compared to a 5-year OS rate of 85% in patients without detectable CTC in the blood (p = 0.002). Detection of DTC in the bone marrow with CK20 RT-PCR was not associated with a worse OS or DFS. Detection of pan-cytokeratin positive DTC in the bone marrow correlated with a significantly reduced 5-year OS rate (p = 0.048), but detection of DTC in the bone marrow with the anti-EpCAM antibody did not significantly influence the 5-year OS rate (p = 0.958). By multivariate analyses only detection of CTC with CK20 RT-PCR in the blood was revealed to be an independent predictor of worse OS (HR1.94; 95% CI 1.0-3.7; p = 0.04) and DFS (HR 1.94; 95% CI 1.1-3.7; p = 0.044). CONCLUSIONS: Detection of CTC with CK20 RT-PCR is a highly specific and independent prognostic marker in colon cancer patients. Detection of DTC in the bone marrow with CK20 RT-PCR or immunohistochemistry with anti-EpCAM antibody is not associated with a negative prognostic influence.

Evaluation of double immunocytochemical staining for CK20 and P53 as a potential adjunct to cytology for urothelial cancer diagnosis.

OBJECTIVE: To evaluate double immunocytochemical staining with p53 and CK20, as a tool for improving the accuracy of urinary cytology. The aim of the present study was to clarify the diagnostic significance of the expression of these markers and to investigate the possibility of using this information for better monitoring of bladder cancer patients during follow-up. MATERIAL AND METHODS: One hundred and twenty-five urine cytology cases were retrieved with corresponding histology from our files. One ThinPrep® smear was available for each of them and dual immunocytological staining for p53 and CK20 was performed. Eleven cases were excluded from the study because of hypocellularity. The material comprised 58 malignant, 36 atypical and 20 negative for malignancy cases. Immunocytochemistry was evaluated by two cytopathologists, blinded to the histological diagnosis or follow-up data. A cut-off threshold of five stained atypical cells, according to the literature, was used for evaluation. RESULTS: Fifty-two out of 58 malignant cases were positive for at least one of the markers (89.6%). In the atypical and negative groups, 18 (50%) and 5 (25%) cases were positive, respectively. Accuracy parameters evaluation for cytology versus the combination of cytology with immunocytological staining were: sensitivity 73.4% versus 91.1%, specificity 100% versus 74.3%, positive predictive value (PPV) 100% versus 88.9% and negative predictive value (NPV) 62.5% versus 78.8%. CONCLUSIONS: Double immunocytochemical staining for p53 and CK20 is easy to perform and evaluate and can improve cytology sensitivity. It is helpful in establishing a diagnosis of malignancy and may be used as a triage tool to select patients that require cystoscopy during clinical follow-up.

Cytokeratin 17 is highly sensitive in discriminating cutaneous lymphadenoma (a distinct trichoblastoma variant) from basal cell carcinoma.

BACKGROUND: Cutaneous lymphadenoma (CL) is rare neoplasm that clinically and histologically resembles basal cell carcinoma (BCC). CL, composed of dermal basaloid epithelial islands with prominent admixed lymphocytes, characteristically contains cytokeratin 20 (CK20)-positive Merkel cells (MCs). However, CK20 may be of limited use because of low MC density in small samples. CK17 is expressed diffusely throughout BCC. We investigated the discriminatory utility of CK17 and CK20 in CL and BCC. METHODS: A retrospective clinicopathological review of 11 cases of CL and 14 BCC was performed. CK20-positive MCs within basaloid tumor lobules and CK17 immunohistochemical staining and pattern of expression were recorded. RESULTS: Intratumoral CK20-positive MCs were identified in 4/11 CL cases (36.4%) and 0/14 BCC cases (p = 0.012, sensitivity = 0.36). CK17 showed diffuse positive staining in all 14 BCC cases. CK17 showed a distinct patchy and peripheral rim staining in basaloid islands of 10/11 CL cases (p < 0.001, sensitivity = 0.91); one case showed patchy staining throughout tumor lobules. CONCLUSIONS: In cases with a differential diagnosis of CL and BCC, CK20 staining of intratumoral MCs has a high positive predictive value for CL but is of low sensitivity. The pattern of CK17 expression is a highly sensitive marker for distinguishing CL from BCC in small samples.

Perianal Paget's disease: case report and review of the literature.

A peri-anal skin lesion, often eczema-like and with symptoms of pruritus, that does not resolve after classical local therapy should be biopsied. We present a case of peri-anal extramammary Paget's disease (EMDP) and associated anal adenocarcinoma. Reviewing the literature, more than 30% of patients with EMDP present a second primary tumour in their past, present or future history. In Europe, the risk of developing a new primary tumour in patients with this condition is increased compared with the standard population. In cases of peri-anal Paget's disease (PPD), specific histochemical markers allow us to differentiate between a primary and a secondary form, the secondary one is strongly associated with colorectal and anal tumours. We provide information about the most commonly suggested therapy for PPD with or without associated malignancy and about the recommended follow-up.

Differential diagnosis of urothelial carcinoma in situ from non-neoplastic urothelia: Analysis of CK20, CD44, P53 and Ki67.

BACKGROUND: Flat urothelial lesions comprise a spectrum of morphologic changes ranging from reactive atypia to carcinoma in situ (CIS). Urothelial dysplasia and CIS are associated with the recurrence and progression of urothelial carcinoma. Distinguishing CIS and dysplasia from reactive atypia based on histolopathogical features alone is often difficult. Using different immunohistochemical markers such as Cytokeratin 20 (CK20), CD44, p53, and Ki-67 is recommended for differential diagnosis. The aim of this study was to evaluate the immunohistochemical pattern of these antibodies to differentiate different flat urothelial lesions. METHODS: In this cross- sectional study, three groups of bladder biopsy specimens were evaluated: 20 samples with reactive urothelial lesions, 20 histologically diagnosed as CIS, and 20 morphologically normal samples. Immunohistochemical staining of CK20, p53, CD44 and Ki-67 markers was performed on paraffin-embedded blocks. The groups were compared using chi square test, and the diagnostic value of the markers were evaluated with sensitivity, specificity, positive and negative predictive values. RESULTS: CK20 was full thickness positive in 15 (75%) CIS samples and negative in all samples of the normal and reactive groups (p<0.001); CD44 was positive in 2 (10%) cases of the CIS group and in 17 (85%) of the reactive group; this marker was negative in all the normal samples (p<0.001). P53 was positive in 12 (60%) samples of the CIS group and negative in all samples of the normal and reactive groups (p<0.001). Ki67 was positive in 13 (65%) samples of the CIS group and 1 (5%) sample of the reactive group. This marker was negative in all samples of the normal group (p<0.001). CONCLUSION: The results of this study revealed that CK20, CD44, P53 and Ki67 are useful in distinguishing CIS from reactive and normal samples. However, they should be used in a panel including at least three markers. Correlation with the morphologic features is necessary.

Altered expression of CKs 14/20 is an early event in a rat model of multistep bladder carcinogenesis.

Cytokeratins (CKs) 14 and 20 are promising markers for diagnosing urothelial lesions and for studying their prognosis and histogenesis. This work aimed to study the immunohistochemical staining patterns of CK14/20 during multistep carcinogenesis leading to papillary bladder cancer in a rat model. Thirty female Fischer 344 rats were divided into three groups: group 1 (control); group 2, which received N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 20 weeks plus 1 week without treatment; and group 3, which received BBN for 20 weeks plus 8 weeks without treatment. Bladder lesions were classified histologically. CK14 and CK20 immunostaining was assessed according to its distribution and intensity. In control animals, 0-25% of basal cells and umbrella cells stained positive for CK14 and CK20 respectively. On groups 2 and 3, nodular hyperplastic lesions showed normal CK20 and moderately increased CK14 staining (26-50% of cells). Dysplasia, squamous metaplasia, papilloma, papillary tumours of low malignant potential and low- and high-grade papillary carcinomas showed increased CK14 and CK20 immunostaining in all epithelial layers. Altered CK14 and CK20 expression is an early event in urothelial carcinogenesis and is present in a wide spectrum of urothelial superficial neoplastic and preneoplastic lesions.

Clinicopathological spectrum of a series of Merkel cell carcinomas diagnosed at a tertiary cancer referral center in India, with current concepts.

Merkel cell carcinoma (MCC) is a rare, clinically aggressive primary cutaneous neuroendocrine carcinoma. The present series describes clinicopathological features of 16 MCCs diagnosed at a tertiary cancer referral center. Sixteen MCCs occurred in 10 men and 6 women (M/F = 1.6:1), between the ages 37 and 74 years (mean, 58.3; median, 58.6), commonly in lower extremities (7) (43.7%) and head and neck sites (5) (31.2%), followed by upper extremities (3) (18.7%) and abdominal wall (1). Tumor size varied from 0.5 to 9.9 cm. Histopathologically, most tumors were composed of round to oval cells, mostly arranged diffusely with hyperchromatic nuclei, including "sudden" pleomorphism in some tumors. Variable features included coexisting Bowen disease (2/16), along with squamous, pseudoglandular, and rhabdomyoblastic dedifferentiation, all in a single tumor. Immunohistochemically, tumor cells were positive for at least a single epithelial marker in all 16 cases (100%) cases, including CK20, mostly paranuclear "dot-like" (12/13, 92.3%); CK (8/9, 88.8%), AE1/AE3 (3/3, 100%), and CK7 (1/6, 16.6%), along with neuroendocrine markers (16/16, 100%), including synaptophysin (11/13, 84.6%), chromogranin (12/15, 80%), and CD56 (4/4, 100%). Among other immunohistochemical markers, positive CKIT/CD117 was positive in 3 of 3 tumors. Surgical resection was performed in 11 (100%) of 11 cases, with adjuvant chemotherapy offered in a single case. Two cases with large-sized tumors, along with another case developed lymph node metastasis, including 1 who later developed pulmonary metastasis. Two patients were free of disease and 2 were alive with disease. Merkel cell carcinomas exhibit a diverse histopathological spectrum, including coexisting Bowen disease and, rarely, rhabdomyoblastic dedifferentiation, in some cases. Optimal immunohistochemical markers include CK20, synaptophysin, chromogranin, and CD56 for a timely diagnosis. Surgical resection is the treatment mainstay. Large-sized tumors and MCCs showing dedifferentiation portend a relatively more aggressive clinical course. Other recent developments in this tumor are discussed herewith.