Unique expression of MUC3, MUC5AC and cytokeratins in salivary gland carcinomas

The differential diagnosis of salivary gland carcinoma is often difficult because of the confusing histopathological features of the different types of salivary gland carcinomas. The expression of MUC3, MUC5AC, MUC6, cytokeratin (CK)7 and CK20 was studied in 20 mucoepidermoid carcinomas (MEC), 20 adenoid cystic carcinomas (AdCC), and 11 acinic cell carcinomas (ACC). All the cases (51/51, 100%) were positive for CK7, but they were not positive for CK20. All the cases (100%) of the MEC were positive for MUC5AC, while all MEC (100%) were negative for MUC3. Only two cases (10%) were positive for MUC6. All cases (100%) of AdCC were negative for MUC3, MUC5AC and MUC6. Eight cases (73%) of ACC were positive for MUC3, but all the cases (100%) were negative for MUC5AC and MUC6. It is concluded that the positive expression of MUC5AC is very unique to MEC, and that the positive expression of MUC3 is very unique to ACC. These findings will be very useful for the differential diagnosis of the salivary gland carcinomas.

The usefulness of CDX-2 for differentiating primary and metastatic ovarian carcinoma: an immunohistochemical study using a tissue microarray

Distinguishing primary ovarian carcinoma from metastatic carcinoma to the ovary is often difficult by histologic examination alone. Recently an immunohistochemical marker CDX-2 was found to be of considerable diagnostic value in establishing the gastrointestinal origin of metastatic tumors. The aim of this study was to determine whether CDX-2 can distinguish between these malignancies. Paraffin-embedded tissue sections from 57 primary ovarian tumors and 40 metastatic tumors to the ovary were immunostained for CDX-2, and results were compared to the ancillary immunohistochemical results for CK7/CK20, CEA, CA125, and her-2/neu. CDX-2 immunoreactivity was observed in most of metastatic carcinomas with colorectal (91%) and appendiceal (100%) origin, however CDX-2 was negative in all primary ovarian carcinomas, except for the mucinous subtype. Almost all primary ovarian carcinomas including the mucinous subtype showed diffuse and strong immunoexpression for CK7. CEA and CA125 were mainly found in metastatic and primary ovarian carcinoma, respectively. Her-2/neu overexpression was only noted in a small proportion of primary and metastatic ovarian carcinomas. These results suggest that CDX-2 is very useful immunohistochemical marker for distinguishing metastatic colorectal carcinoma to the ovary from primary ovarian carcinoma, including the mucinous subtype. Furthermore, combination with CDX-2 and CK7 strengthen the differential diagnosis between these tumors.

[Biopsy methods and pathology of Barrett's esophagus]

We reviewed the definition of the esophagogastric junction and the biopsy sites and histologic findings of biopsy specimens from Barrett's esophagus. The borderline between the esophagus and stomach has been defined as the distal limit of the longitudinal vessels by the Japan Esophageal Society, because the longitudinal vessels are always located within the esophagus. As squamous islands in Barrett's mucosa are usually the orifices of esophageal glands proper, biopsy specimens from the squamous islands show esophageal glands proper or their ducts. The identification of esophageal glands proper is a definite histological indicator that a piece of biopsy tissue is of esophageal origin. Therefore, a diagnosis of Barrett's esophagus can be made purely on the basis of the histologic findings in these biopsy specimens of squamous islands. Since columnar mucosa is usually recognizable at endoscopy, a diagnosis of Barrett's esophagus can be made solely on the basis of endoscopic examination, without any need for histologic confirmation, if squamous islands are recognized in columnar-lined mucosa.

Paratesticular cysts with benign epithelial proliferations of wolffian origin

Paratesticular cysts with benign epithelial proliferations (BEPs) are rare. Only 10 cases were found in a series of 431 paratesticular cysts and were classified as follows: cystadenoma, 5; papilloma, 2; and hamartoma, 3. Four cystadenomas showed multiple papillae lined by CD10+ epithelial cells with hyperchromatic nuclei. The remaining lesion showed areas with a microcystic, glandular, cribriform pattern, with small, benign glands without atypia. Urothelial papilloma presented BEPs with cytokeratin (CK) 7+ and CD10+ and CK20- umbrella-like cells. The mural papilloma was lined by proliferative cylindrical cells exhibiting strong CK7 and CD10 expression. The 3 Wolffian hamartomas were characterized by strongly CD10+ epithelium surrounded by smooth muscle cells. The consistent CD10 expression in BEPs of paratesticular cysts suggests a Wolffian origin. The differential diagnosis of paratesticular cysts with BEP vs metastatic prostatic and primary borderline or malignant tumors is discussed.

Carcinoma ex pleomorphic adenoma (CXPA): immunoprofile of the cells involved in carcinomatous progression

AIMS

To characterize the cellular component in pleomorphic adenoma (PA) that undergoes malignant transformation in carcinoma ex pleomorphic adenoma (CXPA).

METHODS AND RESULTS

A panel of antibodies against cytoskeletal proteins was applied in 16 cases of CXPA: intracapsular carcinoma (five cases), minimally invasive (four cases) and frankly invasive (seven cases). The CXPAs were classified into two main groups according to their predominant cellular component as detected by the panel of antibodies: (i) carcinomas with only epithelial differentiation (75% of the cases), and (ii) carcinomas with a myoepithelial component (25%). CXPA with only epithelial differentiation showed two types of malignant areas in the part of the tumour that was confined by the PA capsule: (i) intraductal carcinoma areas characterized by ductal structures containing both benign myoepithelial cells positive for alpha-smooth muscle actin (alpha-SMA), vimentin and cytokeratin (CK)14 and proliferating atypical luminal cells reactive for CK7, CK8 and CK19, and (ii) carcinoma areas composed only of epithelial cells reactive for CK7, CK8 and CK19. In the latter, the cells presented morphological and immunohistochemical characteristics similar to those found in areas of invasive carcinoma outside the PA capsule. CXPAs with a myoepithelial component were composed mainly or exclusively of cells that expressed vimentin and alpha-SMA. In this group, ductal structures reminiscent of PA filled by malignant cells were not identified.

CONCLUSION

Most CXPAs consist only of epithelial cells that have an immunoprofile comparable to ductal luminal cells of PA. These malignant luminal cells arise in the duct-like structures as intraductal carcinoma and probably only at this early stage of development should the lesion be considered as a non-invasive carcinoma.

Expression of CD10 and Cytokeratins in Ovarian and Renal Clear Cell Carcinoma

A solid pattern of tumor cells with a clear cytoplasm is common to both ovarian clear cell carcinoma (OvCCC) and renal clear cell carcinoma (RCCC). This study examined the possible differential expression of CD10 and cytokeratins (CK7, CK20, 34betaE12, and CAM5.2) between these two types. An immunohistochemical technique using peroxidase-labeled amino acid polymers was used to test formalin-fixed and paraffin-embedded tissues. In OvCCC, 6 of 29 cases were positive for CD10, and all cases had expression of CK7, 34betaE12, and CAM5.2. In contrast, all 24 RCCC cases had CD10 and CAM5.2 immunoreactivity, but none had any staining for 34betaE12. CK7 was only expressed in nine cases. No CK20 positivity was observed in any sample from either tumor type. Localization of CD10 expression was different in OvCCC versus RCCC. Although positive staining for 34betaE12 strongly suggests OvCCC, sometimes only a few cells may be stained. Therefore, 34betaE12-negative biopsies also should be evaluated for CD10 and CK7 immunoreactivity to enable histologic and cytologic differential diagnosis.

[A particular hepatocellular carcinoma combining the ordinary and the fibrolamellar variant]

Fibrolamellar carcinoma (FLC) of the liver is a rare variant of hepatocellular carcinoma (HCC) occurring on non cirrhotic liver. Since its first description by Hugh Edmondson in 1956, 200 cases of FLC have been reported in the literature, but only some cases describe the association of the ordinary HCC with the FLC within the same lesion. We report in this study the case of a 14-year-old female patient with a hepatic mass whose radiological aspect evoked a nodular and focal hyperplasia. Histologically, this tumor was composed of area of FLC mixed with ordinary HCC. Staining for cytokeratine 7 was positive in the FL component and negative in the ordinary HCC component.

Immunophenotypic comparison of salivary gland oncocytoma and metastatic renal cell carcinoma

OBJECTIVES/HYPOTHESIS

The differential diagnosis of oncocytic neoplasms of salivary glands includes both primary and metastatic tumors, one of which is renal cell carcinoma. This study compared immunohistochemical staining characteristics of oncocytomas arising from salivary gland to metastatic renal cell carcinoma using a panel of markers.

STUDY DESIGN

Immunohistochemistry for cytokeratin 7 (CK7), cytokeratin 20 (CK20), epithelial membrane antigen (EMA), vimentin, CD10, and renal cell carcinoma marker (RCC) was performed on 10 oncocytomas and compared with ten metastatic renal cell carcinomas.

RESULTS

There were overlapping histologic findings in the oncocytomas and metastatic renal cell carcinomas, with oncocytomas displaying clear cell changes in 2 of 10 cases. CK7 was positive in 9 of 10 oncocytomas and CK20 in 8 of 10 (7/10 stained for both), and vimentin was only weakly positive in 4 of 10 oncocytomas. All oncocytomas were EMA positive, with membranous staining, and all were negative for CD10 and RCC. Metastatic renal cell carcinoma was strongly positive for vimentin, EMA, and CD10 in most cases. RCC and CK7 were variably positive in metastatic renal cell carcinomas (4/10), and only 1 of 10 showed weak staining with CK20.

CONCLUSIONS

Salivary gland oncocytomas and metastatic renal cell carcinomas share some similar histologic and immunohistochemical characteristics. CD10 and CK20 were the most useful markers to distinguish metastatic renal cell carcinoma from oncocytomas in the salivary gland, whereas RCC, EMA, CK7, and vimentin are not as useful.

Is cytokeratin immunoreactivity useful in the diagnosis of short-segment Barrett's oesophagus in Korea?

BACKGROUND

Cytokeratin 7/20 staining has been reported to be helpful in diagnosing Barrett's oesophagus and gastric intestinal metaplasia. However, this is still a matter of some controversy.

OBJECTIVE

To determine the diagnostic usefulness of cytokeratin 7/20 immunostaining for short-segment Barrett's oesophagus in Korea.

METHODS

In patients with Barrett's oesophagus, diagnosed endoscopically, at least two biopsy specimens were taken from just below the squamocolumnar junction. If goblet cells were found histologically with alcian blue staining, cytokeratin 7/20 immunohistochemical stains were performed. Intestinal metaplasia at the cardia was diagnosed whenever biopsy specimens taken from within 2 cm below the oesophagogastric junction revealed intestinal metaplasia. Barrett's cytokeratin 7/20 pattern was defined as cytokeratin 20 positivity in only the superficial gland, combined with cytokeratin 7 positivity in both the superficial and deep glands.

RESULTS

Barrett's cytokeratin 7/20 pattern was observed in 28 out of 36 cases (77.8%) with short-segment Barrett's oesophagus, 11 out of 28 cases (39.3%) with intestinal metaplasia at the cardia, and nine out of 61 cases (14.8%) with gastric intestinal metaplasia. The sensitivity and specificity of Barrett's cytokeratin 7/20 pattern were 77.8 and 77.5%, respectively.

CONCLUSION

Barrett's cytokeratin 7/20 pattern can be a useful marker for the diagnosis of short-segment Barrett's oesophagus, although the false positive or false negative rate is approximately 25%.

Cytokeratin immunoreactivity patterns in short-segment Barrett's esophagus in Japanese patients

BACKGROUND

The origin of intestinal metaplasia at the esophagogastric junction has clinical importance. However, it can be difficult to differentiate between intestinal metaplasia of short-segment Barrett's esophagus and cardiac intestinal metaplasia due to Helicobacter pylori infection. Specific patterns of cytokeratin (CK)7 and CK20 have been detected in long-segment Barrett's esophagus. The aim of the present study was to assess the immunostaining patterns associated with short-segment Barrett's esophagus.

AIMS

Paraffin-embedded biopsy specimens were prepared from 128 patients with intestinal metaplasia of long-segment Barrett's esophagus (n = 3), short-segment Barrett's esophagus without H. pylori infection (n = 22), short-segment Barrett's esophagus with H. pylori infection (n = 22), and cardiac mucosa (n = 49) and gastric mucosa from antrum and fundus (n = 44) with H. pylori infection. Sections were prepared and immunostained for CK7 and CK20.

RESULT

A Barrett's CK7/20 pattern was present in all three patients (100%) with long-segment Barrett's esophagus, 21 of 22 patients (95%) with short-segment Barrett's esophagus without H. pylori infection, and six of 22 patients (27%) with short-segment Barrett's esophagus with H. pylori infection (P < 0.05).

CONCLUSION

Intestinal metaplasia of short-segment Barrett's esophagus in patients without H. pylori infection is thought to be similar to that seen in long-segment Barrett's esophagus.

Free-flow isoelectric focusing of proteins remaining in cell fragments following sonication of thyroid carcinoma cells

The method of preparing protein mixtures for electrophoretic analysis of membrane-associated cell proteins was improved. By sonication, about one-half of the proteins of thyroid cells were released into the supernatant, while the other half preferentially comprising membrane proteins still remained in cell fragments, which could be sedimented by centrifugation. After sonication, even those proteins which remained in cell fragments, could completely be dissolved by free-flow isoelectric focusing media. They migrated through the free-flow electrophoresis chamber without forming precipitates. Because of these improvements, it was possible to show that the two thyroid cancer cell lines ML-1 and ONCO-DG1 express cytokeratin 8 at similar rates, but cytokeratins 7 and 18 differently. In addition, the presence of inorganic pyrophosphatase, tubulin-beta-5, and tubulin-beta-1 chains in human thyroid cells was proved for the first time.

Hybrid chromophobe renal cell neoplasm

Hybrid renal cell neoplasms (HRCNs) containing areas of tumor cells displaying cytological features of chromophobe renal cell carcinoma (CHRCC) and renal oncocytoma (RO) have been recently described in patients with renal oncocytosis and Birt-Hogg-Dube (BHD) syndrome (autosomal dominant genodermatosis). In this study, we identified cases of sporadic HRCN. We reviewed 425 consecutive renal cell carcinomas (RCC), 18 CHRCC, six HRCN, and 25 RO. Five HRCN were identified, including four from the group of RCC and two from RO. Patient age ranged from 40 to 68 years (mean age: 54 years), and the male:female ratio was 4:1. Tumors measured from 1.8 to 5 cm (mean diameter: 3.0 cm). Tumoral necrosis was not seen. Vascular invasion into medium-sized veins was identified in one HRCN. Chromophobe cells accounted for 20-80% of the tumors. Hale's colloidal stain showed weak to moderate diffuse cytoplasmic staining in scattered cells corresponding to those displaying routine staining features of chromophobe cells. Areas of oncocytic cells in studied tumors and control oncocytomas showed negative or focal cytoplasmic staining usually bordering extra- or intra-cytoplasmic lumina. Immunostaining for cytokeratin 7 and vimentin showed focal immunoreactivity in three cases and negative reactivity in all six cases, respectively. None of the study cases had microscopic RO, as commonly seen in renal oncocytosis, or were associated with BHD syndrome Sporadic HRCN accounted for 1% of RCC. They were of smaller size than RCC and were associated with a favorable prognosis.

Pulmonary intestinal-type adenocarcinoma does not show enteric differentiation by immunohistochemical study

Six cases of an unusual variant of primary pulmonary adenocarcinoma resembling colorectal and sinonasal adenocarcinoma are presented. Pulmonary intestinal-type adenocarcinoma occurs in elderly Caucasians and is associated with a histology characteristic of colorectal/enteric adenocarcinoma: a garland-like architecture with a 'gland in gland' periphery, central 'dirty' necrosis, and elongated stratified columnar cells, lacking significant goblet or signet ring differentiation. While a resemblance to intestinal adenocarcinoma by light microscopy is present, immunohistochemical studies comparing these carcinomas with metastatic colorectal adenocarcinoma clearly show a respiratory phenotype with the neoplastic cells expressing thyroid transcription factor-1 and cytokeratin 7 to the exclusion of cytokeratin 20, and failing to express CDX-2. Stains for a variety of epithelial mucins (MUC1, MUC2, MUC5AC) also support this observation. The differential diagnosis with other pulmonary adenocarcinomas, especially those with mucinous differentiation, is discussed.

Vulvar Clear Cells of Toker

Clear cells of Toker are intraepithelial cells with clear to pale staining cytoplasm and bland cytologic features found with H&E staining in approximately 10% of normal nipples. Toker cells have been hypothesized as a precursor of extramammary Paget's disease (EMPD), although Toker cells have not been identified as a normal component of genital skin. Using immunohistochemistry, we studied 11 vulvectomies for the presence of Toker cells in association with mammary-like glands of the vulva (MLG). A retrospective study of 11 vulvectomies was performed using routine hematoxylin and eosin staining, as well as immunohistochemical staining for cytokeratin 7 (CK7). Control sections of skin not involving the milk line from age-matched patients were also examined. Four of eleven vulvectomies (36%) demonstrated Toker cells with CK7 staining. Toker cells were associated with the openings of the ducts of mammary-like glands of the vulva. Toker cells were not seen in control tissues. Toker cells occur as a normal constituent of genital skin in association with mammary-like glands of the vulva. Previous morphologic, immunohistochemical, and ultrastructural evidence have pointed to Toker cells as a precursor of EMPD. The demonstration of Toker cells in genital skin strengthens the evidence of their role in the development of EMPD.

Cytokeratins 7 and 20 and mucin core protein expression in esophageal cervical inlet patch

Cervical inlet patch (CIP) is defined by the presence of gastric mucosa within the first few centimeters of the esophagus. Several endoscopic series have demonstrated a frequent association of CIP with Barrett's esophagus (BE) suggesting a pathogenetic link. A histochemical study reporting the presence of acid mucin in CIP, including sulfomucin, supports this hypothesis. We evaluated mucin core protein expression and cytokeratins 7 and 20 (CK7/CK20) pattern in biopsies of CIP, normal antrum, and BE to comment on a possible relationship of CIP with BE. We observed that both lesions have similar cytokeratin patterns with mixed CK7/CK20 reactivity on the surface and pits and lone CK7 positivity in the glands. MUC5AC was strongly expressed on the surface and pits but not in the glands of CIP and antral mucosa. Within BE, MUC5AC positivity was noted not only on the surface and pits but also in the glands. MUC6 similarly decorated the glands of CIP and BE. MUC2 was expressed rarely in CIP with goblet cells but conspicuously on the surface and pits of BE. MUC5B was seen in both CIP and BE and rarely in the antral mucosa. The similarities between CIP and BE but not with normal antral mucosa fits with the hypothesis that both lesions may originate from submucosal esophageal mucous glands. Two pathogenetic pathways can be entertained: focal upper esophageal mucosal misdevelopment in pediatric population and patchy metaplastic replacement of squamous mucosa in adults with gastroesophageal reflux disease.

CK20 and CK7 protein expression in colorectal cancer: demonstration of the utility of a population-based tissue microarray

The ability to use archival tissue to test externally valid hypotheses of carcinogenesis is dependent on the availability of population-based samples of cancer tissue. Tissue microarrays (TMAs) provide an efficient format for developing population-based samples of tissue. A TMA was constructed consisting of archival tissue from patients diagnosed with invasive colorectal cancer in the state of Hawaii in 1995. The population representativeness of the TMA was evaluated by comparing patient and clinical characteristics of TMA cases to that of all cases of colorectal carcinoma diagnosed statewide in 1995. Cytokeratin 20 (CK20) and cytokeratin 7 (CK7) immunohistochemistry was used to validate the utility of the TMA, and the expression of these proteins was correlated with patient and tumor characteristics. The TMA comprised tissue specimens from 286 patients representing 47% of all invasive cases diagnosed statewide in 1995. TMA cases were comparable to all invasive colorectal cases statewide with respect to age, sex, race/ethnicity, anatomic site, and survival. There were some differences between TMA cases and all cases with respect to tumor stage, histological classification, and treatment. There were significant differences in the relative expression of CK20 and CK7 proteins between malignant and normal tissues and by tumor stage. Advanced cancers were more likely to have CK20+/cytokeratin 7+ (CK7+) profiles than early-stage cancers, which were predominantly CK20+/cytokeratin 7- (CK7-). CK7+ expression was not correlated with anatomic location of carcinomas. This well-characterized TMA offers a powerful tool for testing hypotheses regarding colorectal carcinogenesis, including the identification of potential markers of neoplastic development and progression.

Ovarian carcinomas, including secondary tumors: diagnostically challenging areas

The differential diagnosis of ovarian carcinomas, including secondary tumors, remains a challenging task. Mucinous carcinomas of the ovary are rare and can be easily confused with metastatic mucinous carcinomas that may present clinically as a primary ovarian tumor. Most of these originate in the gastrointestinal tract and pancreas. International Federation of Gynecology and Obstetrics (FIGO) stage is the single most important prognostic factor, and stage I carcinomas have an excellent prognosis; FIGO stage is largely related to the histologic features of the ovarian tumors. Infiltrative stromal invasion proved to be biologically more aggressive than expansile invasion. Metastatic colon cancer is frequent and often simulates ovarian endometrioid adenocarcinoma. Although immunostains for cytokeratins 7 and 20 can be helpful in the differential diagnosis, they should always be interpreted in the light of all clinical information. Occasionally, endometrioid carcinomas may exhibit a microglandular pattern simulating sex cord-stromal tumors. However, typical endometrioid glands, squamous differentiation, or an adenofibroma component are each present in 75% of these tumors whereas immunostains for calretinin and alpha-inhibin are negative. Endometrioid carcinoma of the ovary is associated in 15-20% of the cases with carcinoma of the endometrium. Most of these tumors have a favorable outcome and they most likely represent independent primary carcinomas arising as a result of a Mullerian field effect. Although the criteria for distinguishing metastatic from independent primary carcinomas rely mainly upon conventional clinicopathologic findings, loss of heterozygosity and gene mutation analyses can be helpful. Transitional cell carcinomas are distinguished from undifferentiated carcinomas by the presence of thick, undulating papillae with smooth luminal borders, microspaces, and tumor cells with distinctive 'urothelial' appearance. Krukenberg tumors are metastatic adenocarcinomas traditionally perceived as composed of mucin-filled signet-ring cells associated with a striking proliferation of the ovarian stroma but many variations on this pattern occur.

Pulmonary mucoepidermoid carcinoma with prominent tumor-associated lymphoid proliferation

We report 6 cases of low-grade pulmonary mucoepidermoid carcinoma displaying a striking lymphoplasmacytic infiltrate. All six tumors had a typical pulmonary mucoepidermoid carcinoma presentation as a polypoid endobronchial mass involving the proximal bronchi. The patients were 3 females and 3 males with a mean age of 33 years (range, 5-61 years). Half of the patients were asymptomatic, while half experienced mild symptoms of pneumonia, asthma-like symptoms, or hemoptysis. No tumor-related deaths were observed, with a mean follow-up of 51 months. The tumor size ranged from 2.1 to 3.4 cm (mean, 2.9 cm). The tumors characteristically displayed an elaborate tubulocystic epithelial component composed of intermediate, epidermoid, and mucus-producing cells, and variable numbers of clear cells, multinucleated giant cells, columnar cells, and oncocytic cells. The tumors' lymphoplasmacytic infiltrate with occasional Russell bodies was sufficiently intense to raise concern of a low-grade lymphoma. All tested tumors were immunoreactive with CK7 while nonreactive with TTF-1 and CK20. Recognition of this histologic variant is important for a correct diagnosis of low-grade pulmonary mucoepidermoid carcinoma. The dense lymphoplasmacytic infiltrate is similar to that previously described in salivary glands as tumor-associated lymphoid proliferation.

Hepatic adenocarcinoma expressing inhibin in a young patient on oral contraceptives

A case of primary hepatic carcinoma is reported, which occurred in a 24-year-old woman with a 10-year history of oral contraceptive use, and demonstrated unique morphologic and immunohistochemical features. The tumor was located in the left hepatic lobe, measured 14 cm at its widest, and showed histologic heterogeneity. The neoplastic cells were mostly arranged in trabecular and pseudoglandular growth patterns simulating hepatocellular carcinoma; however, in focal areas, small cystic, organoid and tubular patterns predominated. Immunohistochemical stains showed a phenotype consistent with biliary differentiation (positive staining for cytokeratin 7, cytokeratin 19, carcinoembryonic antigen and CA 19-9 antigen). The tumor cells were negative for markers that would be suggestive of hepatocytic or neuroendocrine differentiation. Interestingly, they were positive for inhibin, a protein that is known to be expressed in sex cord-stromal tumors of the ovary, trophoblastic neoplasms and adrenal cortical tumors, but not in hepatic tumors. However, no definite evidence of gonadal stromal, trophoblastic, or adrenocortical differentiation was identified on extensive immunohistochemical work-up. In conclusion, this unique case may represent a rare variant of cholangiocarcinoma expressing inhibin.

Mucin-producing urothelial-type adenocarcinoma of prostate: report of two cases of a rare and diagnostically challenging entity

The differential diagnosis of mucin-producing adenocarcinoma of the prostate includes conventional prostatic adenocarcinoma with mucin production, secondary adenocarcinoma usually of colorectal origin and, very rarely, urothelial-type adenocarcinoma arising from either the prostatic urethra or proximal ducts. Conventional prostatic adenocarcinoma with mucin production is readily identified by routine microscopy and immunohistochemistry. The distinction between secondary adenocarcinoma and urothelial-type adenocarcinoma, however, can present a significant diagnostic challenge. In addition, documented examples of the latter in the prostate are exceptionally rare. A transurethral resection of prostate specimen and prostatic needle biopsies from two patients showing urothelial-type adenocarcinoma of the prostate were identified in our consultation files. One of the patients subsequently underwent a radical prostatectomy. Both patients had negative gastrointestinal endoscopic workups. Transurethral resection of prostate material from two patients with clinically confirmed secondary adenocarcinoma of colonic origin involving the prostate and a prostatectomy specimen with mucinous conventional prostatic adenocarcinoma were also identified for comparison purposes. Formalin-fixed, paraffin-embedded sections were stained for prostate-specific antigen (PSA), prostatic acid phosphatase, carcinoembryonic antigen, cytokeratin 7, cytokeratin 20 and high molecular weight cytokeratin 34betaE12. The urothelial-type adenocarcinoma cases were diffusely positive for cytokeratin 7 and focally positive for 34betaE12 and cytokeratin 20, consistent with an origin from the urothelium of the prostatic urethra or proximal prostatic ducts. In contrast, the secondary adenocarcinoma of colonic origin cases were diffusely cytokeratin 20 positive and either negative or focally positive for cytokeratin 7 and negative for 34betaE12. The mucinous conventional prostatic adenocarcinoma was positive for PSA and prostatic acid phosphatase and negative for cytokeratin 7, cytokeratin 20 and 34betaE12. All tumors were positive for carcinoembryonic antigen.

Intrahepatic cholangiocarcinoma with multicystic, mucinous appearance and oncocytic change

A case is reported herein of intrahepatic cholangiocarcinoma (ICC) with multicystic, mucinous appearance and oncocytic change. Because of liver dysfunction, a 73-year-old woman was hospitalized in early October 2003. She was diagnosed as having ICC of the right hepatic lobe with occlusion of the hilar and perihilar bile ducts by imaging examination. Extended right lobectomy was performed but the patient died of liver failure on the next day. In surgically resected specimens, the tumor (3 x 3 cm) was mainly located in the right lobe, and tumors infiltrated along the biliary tree as well as invading into the adjacent hepatic parenchyma. The tumor mass had a sponge or honeycomb appearance. Microscopically, these tumors were composed of multiple microcysts filled by abundant mucin and lined by micropapillary adenocarcinoma cells. Their cytoplasm was acidophilic, appearing as an oncocyte, and carcinoma cells were positive for mitochondrial antigen in addition to biliary cytokeratins. There were no ovarian-like stromas around these cystic tumors, and communication of the biliary lumen with these carcinomatous cysts was not evident, thus different from biliary mucinous cystadenocarcinoma and intraductal papillary neoplasm of the liver. This is the third case of multicystic mucinous ICC and the present case might have been derived from intrahepatic peribiliary glands.

Renal oncocytosis

Renal oncocytosis is a rare disorder in which numerous oncocytic nodules develop in the kidney. An additional case is reported here. The patient was a 51-year-old woman who had received hemodialysis for 27 years. Nineteen years previously she had developed a tumorous lesion in the right kidney, which had been diagnosed as oncocytoma with laparotomic biopsy. Recently the kidney was removed because of enlargement of the tumor. The renal parenchyma was entirely replaced with numerous brownish nodules. Histologically, the nodules were composed of nests of uniform oncocytic cells. Ultrastructurally, the oncocytic cells contained numerous mitochondria. Immunohistochemical features of the nodules were identical to those of sporadic oncocytomas, that is, immunophenotypes similar to the distal nephron and reactivity with antimitochondrial antigen. Based on these findings, the lesion was diagnosed as renal oncocytosis. It was not possible to determine whether the larger nodules should be diagnosed as oncocytoma or a part of oncocytosis. Additionally, the germ line mutation of the Birt-Hogg-Dubé (BHD) syndrome gene was examined using the genomic DNA obtained from the peripheral lymphocytes, which failed to show any gene alteration. Despite the rare occurrence pathologists and urologists should be aware of renal oncocytosis, as a precursor lesion of renal oncocytoma and chromophobe renal cell carcinoma.

Expression of aquaporins and PAX-2 compared to CD10 and cytokeratin 7 in renal neoplasms: a tissue microarray study

Diagnostic use of antibodies against aquaporin water channel proteins and PAX-2, a nuclear transcription factor in renal development, was tested in 202 renal neoplasms, using tissue microarray technique. Immunohistochemistry for aquaporin-1, aquaporin-2, PAX-2, CD10, and cytokeratin 7 was performed on 102 clear cell renal cell carcinomas, 44 papillary renal cell carcinomas (among them 34 type 1 and 10 type 2), 24 chromophobe renal cell carcinomas, three collecting duct carcinomas (carcinomas of the collecting ducts of Bellini), and 29 oncocytomas. Aquaporin-1 expression was found in clear cell renal cell carcinomas and papillary renal cell carcinomas of both types (78 and 73%, respectively), but not in chromophobe renal cell carcinomas, collecting duct carcinomas, and oncocytomas. Aquaporin-2 expression was not seen in any of the tested tumors. PAX-2 and CD10 was found in the majority of clear cell renal cell carcinomas (88 and 85%, respectively) but only in few papillary renal cell carcinomas, chromophobe renal cell carcinomas and oncocytomas. Decrease or loss of aquaporin-1 and PAX-2 was shown in higher grades compared to lower grades of clear cell renal cell carcinomas (P<0.0001 and <0.0245, respectively). Cytokeratin 7 was rarely seen in clear cell renal cell carcinomas, type 2 papillary renal cell carcinomas, and oncocytomas, but was found in the majority of type 1 papillary renal cell carcinomas (97.1%) and chromophobe renal cell carcinomas (88%). Aquaporin-1 and PAX-2 expression was found to correlate with nuclear grading for clear cell renal cell carcinomas but not for papillary renal cell carcinomas. No correlation of tumor stage and aquaporin-1 and PAX-2 expression was seen. Aquaporin-1 and PAX-2 are reliable markers for clear cell renal cell carcinomas of lower grades but not for higher grades. CD10 expression remains stable, independent of nuclear grading.