Sarcomatoid Areas Research Articles

Expression of carbonic anhydrase IX (CAIX) in malignant mesothelioma. An immunohistochemical and immunocytochemical study

Malignant mesothelioma is an aggressive tumor with a poor prognosis. Carbonic anhydrase IX (CAIX) is a membranously located metalloenzyme involved in pH homeostasis with influence on regulation of cell proliferation, oncogenesis and tumor progression. Much attention has been paid recently to carboanhydrases and their inhibitors as they offer an opportunity for both developing novel anticancer drugs, as well as diagnostic and prognostic tools. This study was designed to assess the expression of CAIX in malignant pleural and peritoneal mesotheliomas, their benign counterparts, and in pleural effusions from patients with malignant mesothelioma, metastatic carcinoma or a benign disease. Tissue blocks from 51 malignant mesotheliomas of pleura (47 cases; 41 epithelioid, 2 biphasic, 4 sarcomatoid) and peritoneum (4 cases; all epithelioid), 14 cases with normal or reactive pleural tissue, and 19 cell blocks were analyzed. CAIX expression was determined using immunohistochemistry and its membranous immunoreactivity was semiquantitatively evaluated. Specimens were divided into five subgroups according to the staining pattern and intensity.Overall, 92.2% (47/51) of mesotheliomas expressed CAIX. All epithelioid mesotheliomas showed CAIX positivity, which was predominantly strong and diffuse (73.3%, 33/45). Sarcomatoid mesotheliomas and sarcomatoid areas in biphasic mesotheliomas were negative. A strong diffuse staining was observed in all cases of normal mesothelia. In pleural effusions, CAIX expression was observed in malignant cells as well as in benign mesothelial cells. In conclusion, CAIX is expressed virtually in all mesotheliomas except for sarcomatoid subtype, and in benign mesothelia. There are probably more mechanisms of CAIX overexpression than hypoxia-induced in malignant mesothelioma, with the influence of other tissue specific transcription or growth factors depending on the type of the cell lineage. CAIX immunoreactivity is not a reliable diagnostic marker for distinguishing malignant cells from benign mesothelia in pleural effusions. Nevertheless, our data support the potential use of therapeutics targeting CAIX in patients with advanced mesothelioma.

Survivin Expression in Renal Epithelial Tumors: It's Usage in the Differential Diagnosis of Eosinophilic Renal Epithelial Tumors

Objective: The differential diagnosis of renal tumors can be problematic due to overlapping morphologic features. The purpose of this study was to assess the potential contribution of survivin expression in the differential diagnosis and determination of therapy modalities of these tumors. Methods: This study consisted of 15 chromophobe (ChRCC), 15 clear cell (CCRCC) and 9 papillary (PRCC) renal cell carcinomas, and 13 oncocytomas. Sections were stained against survivin antibody. Results: PRCCs and CCRCCs showed diffuse and strong survivin expression. Survivin expression was strikingly prominent in type1 PRCCs and cystic CCRCCs. In CCRCCs, survivin expression was more pronounced in low grade areas than high grade and sarcomatoid areas. In ChRCC, survivin expression was more limited and weaker than that of oncocytomas and other malignant renal tumors. In non-neoplastic renal tissue, survivin expression was more pronounced in podocytes and atrophic tubules than other nephron parts. Conclusions: Our results suggested that survivin may helpful in the differential diagnosis of renal tumors despite limited number of our cases. Experimental studies have revealed that inhibition of survivin induces apoptosis and enhance radiosensitivity of RCC cells. Taken together, to be known the proportion of survivin expression in subtypes of renal tumors may contribute to determine new therapeutic strategies for RCCs. This needs to be proven in more wide series.

Chromophobe renal cell carcinoma: a morphologic and immunohistochemical study of 45 cases

The aim of this study was to evaluate the morphological spectrum of chromophobe renal cell carcinoma (CRCC) and diagnostic utility of a panel of three immunohistochemical stains. All cases of CRCC reported between 2002 and 2012 in the Section of Histopathology, Aga Khan University Hospital, were retrieved. A total of 45 cases were identified. Slides were reviewed and immunohistochemical stains (CK7, CD117, and vimentin) were performed. Ages ranged from 18 to 90 years (mean, 48.5 years). Male-to-female ratio was 0.8:1. The tumor was located in the left kidney in 24 patients and the right kidney in 20 patients. The tumor size ranged from 3.5 to 22 cm (mean 10 cm). Histologically, 4 were classic, 22 were eosinophilic, 16 were mixed, and 3 were sarcomatoid type. Morphologic patterns included broad alveolar, solid, nested, tubular, tubulocystic, trabecular, papillary, and microglandular. Binucleation and perinuclear halos were seen in all cases. Nuclear grooves and pseudoinclusions were seen in 17 and 6 cases, respectively. Multinucleated cells were seen in 19 cases. Mitoses ranged from 1 to 11/10 HPFs (mean 3/10 HPFs). Hyalinized stroma was seen in 38 cases and calcification in 26 cases. Necrosis was seen in 18 cases. Palisading of smaller cells around the broad alveolar pattern was noted in 5 cases. The Furhman's nuclear grade was I (11), II (26), III (5), and IV (3). Hale's colloidal iron was positive in all cases. Immunohistochemical stain CK7 and CD117 were positive in 100% and 95.5% of cases respectively. Vimentin was negative in all cases, except in the sarcomatoid areas of 3 cases. In conclusion, chromophobe renal cell carcinoma has certain unique morphological features and immunohistochemical profile which help to distinguish it from conventional renal cell carcinoma and oncocytoma. We identified nuclear pseudoinclusions, microglandular pattern and palisading of smaller cells, which have not been reported earlier.

Diffuse mesothelioma of the peritoneum: a pathological study of 64 tumours treated with cytoreductive therapy

Diffuse peritoneal mesothelioma (DPM) forms a spectrum of indolent surface tumours to malignant invasive cancers. There are few pathological series that span well and poorly differentiated lesions that show diffuse peritoneal spread. Sixty-four DPM treated by initial cytoreductive therapy were retrospectively reviewed. Tumours were classified by surface and invasive growth pattern and correlated with risk factors, peritoneal cancer index (PCI) and completeness of cytoreduction (CCR). Degree of invasion was quantitated as absent (0), into stroma (I), into fat (II), and into adjacent structures (III) and was correlated with cytological features. Selected immunohistochemical stains were performed. There were three well differentiated papillary mesotheliomas (WDPM; type A), four multicystic mesothelioma (type B), 22 tubulopapillary epithelioid mesotheliomas (type C), and 35 poorly differentiated epithelioid mesotheliomas with solid or sarcomatoid growth (Type D). Seven type D tumours had prominent sarcomatoid areas, 12 deciduoid areas, and four lymphohistiocytoid features. Risk factors were present in all groups except type A, and included prior abdominal surgery (n=24), asbestos exposure (n=5) and radiation (n=2). Extra-pleural mesothelioma was present in all groups except type B (total n=7, 11%). Two type A and eight type C tumours lacked invasion; only type D showed level III invasion. The invasive portion of one type A tumour and two type B tumours showed adenomatoid features. PCI and CCR were greater in type D compared to the other groups (p=0.02), as well as mitotic rate, degree of necrosis, and nuclear pleomorphism (p<0.001). Degree of invasion was strongly correlated with CCR (p=0.007), necrosis (p<0.0001), nuclear grade (p<0.0001), and mitotic rate (p=0.001), but not PCI (p=0.1). Immunohistochemical results were similar across groups, with frequent positivity for CA125 (94%), EGFR (94%) and calretinin (93%), followed by p16 (85%), cytokeratin 5,6 (76%), D2-40 (71%) and WT-1 (47%). PAX-8 was negative in all tumours, except one type A tumour that showed diffuse nuclear positivity. Diffuse peritoneal mesotheliomas can be classified into four groups that reflect invasive potential, degree of adverse histological features, and amenability for CCR. Non-invasive tumours include both type A and type C tumours.

Prognostic Effect of Sarcomatoid Dedifferentiation in Patients With Surgically Treated Renal Cell Carcinoma: A Matched-Pair Analysis

BackgroundThe aim of this study was to assess the prognostic relevance of SD in patients with RCC. Patients and MethodsAmong 8126 RCC patients surgically treated at 12 academic centers (members of the Collaborative Research on Renal Neoplasms Association [CORONA] project), 316 patients (3.9%) had SD with sarcomatoid areas comprising at least 10% of the tumor tissue. After propensity score-based matched-pair analysis, 281 with and 281 matched RCC patients without SD remained available for direct comparison of cancer-specific survival (CSS). Median follow-up was 36.5 months (interquartile range, 15-82). Uni- and multivariable Cox proportional hazards regression analyses were performed to assess the prognostic value of parameters. ResultsIn univariable analysis, there was no difference in CSS between patients with or without SD (1 and 5 years CSS, 79% vs. 83% and 59% vs. 64%, respectively; hazard ratio, 1.21; P = .16). Multivariable analysis in patients with SD identified metastatic dissemination at the time of surgery, pT-stage, nodal status, and tumor size as independent predictors of CSS. This study was limited by its retrospective multicenter design and lack of central histopathological review. ConclusionSarcomatoid dedifferentiation was not an independent predictor of CSS in surgically treated RCC patients in the present matched-pair series. Because pathology reports form the basis on which study specimens are selected for further studies, which are clearly needed to advance our understanding of the prognostic value of SD in RCC, it is imperative that pathologists reliably report on absence or presence and the estimated percentage of a coexisting sarcomatoid component.

Laparoscopic left pancreatectomy for pancreatic sarcomatoid carcinoma: A case report and review of the literature

Sarcomatoid carcinoma of the pancreas is extremely rare. The current report presents a case of carcinosarcoma of the pancreas in a 48-year-old male. Pre-operative computed tomography scans revealed a large complex cystic and solid mass in the tail of the pancreas; the patient underwent a laparoscopic spleen-preserving left pancreatectomy. The tumor was shown to be made of cystic and solid components, with a grossly grey/ white appearance. A histological evaluation of the tumor revealed two elements separated from each other, one component was a pancreatic ductal adenocarcinoma and the other component exhibited a sarcomatous growth pattern, composed of spindle cells and multinucleated giant cells. Immunohistochemically, the epithelial area was positive for cytokeratin (CK) and negative for vimentin, while the sarcomatoid area was negative for CK and positive for vimentin. These observations confirmed a diagnosis of pancreatic carcinosarcoma. Although the patient was treated by gemcitabine following surgery, the outcome was extremely poor and the patient succumbed to sarcomatoid carcinoma three months after the treatment.

Use of PAX8 and GATA3 in diagnosing sarcomatoid renal cell carcinoma and sarcomatoid urothelial carcinoma

Immunohistochemistry for PAX8 and GATA3 are sensitive markers for renal cell carcinoma and urothelial carcinoma, respectively. However, there are limited data on these markers in sarcomatoid renal cell carcinoma (SARCRCC) and sarcomatoid urothelial carcinoma (SARCUC). Tissue microarrays (TMAs) were constructed from 45 cases of SARCRCC and 45 cases of SARCUC of the lower urinary tract, with an additional 11 SARCUCs of the upper tract. PAX8 and GATA3 were also evaluated in TMAs from 161 sarcomas from other sites, 14 atypical epithelioid angiomyolipomas (AMLs) of the kidney, 23 bladder inflammatory myofibroblastic tumors (IMTs), and 2 bladder and 4 renal leiomyosarcomas. In the SARCRCC, PAX8 and GATA3 were positive in the sarcomatoid areas in 31 (69%) and 0 (0%) of cases, respectively. In the bladder SARCUC, GATA3 and PAX8 were positive in 14 (31%) and 2 (4%) of cases, respectively. Of the 11 SARCUCs of the upper urinary tract, 2 (18%) cases were PAX8 positive and 2 (18%) separate cases were GATA3 positive. Only 1 tumor present on the sarcoma TMAs, a Ewing sarcoma/primitive neuroectodermal tumor, was PAX8 positive, and all sarcomas were GATA3 negative. Of the AMLs, IMTs, and leiomyosarcoma, only 1 case of IMT showed moderate GATA3 positivity, and all were negative for PAX8. PAX8 can be used to distinguish SARCCRCC from atypical epithelioid AMLs and primary renal or retroperitoneal sarcomas. However, in a kidney/renal pelvic tumor, PAX8 shows overlap in staining between SARCUC and SARCRCC. GATA3 lacks sensitivity but is more specific for SARCUC.

Acquired cystic disease-associated renal cell carcinoma: an immunohistochemical and fluorescence in situ hybridization study

Acquired cystic disease (ACD)-associated renal cell carcinoma (RCC) has been recently identified. However, there are only a few genetic studies to date. In this article, we performed an immunohistochemical and fluorescence in situ hybridization (FISH) study for six cases including one case with sarcomatoid change. As a result, we observed frequent immunohistochemical expression of AMACR. FISH of chromosome 3 showed trisomy for three cases, monosomy for two cases, and disomy for one case. Additionally, FISH of chromosome 16 showed trisomy for three cases, monosomy for two cases, and both trisomy and monosomy for one case. Furthermore, both the carcinomatous area and the sarcomatoid area of one ACD-associated RCC with sarcomatoid change revealed monosomy of chromosomes 3, 9, and 16 but showed disomy of chromosome 14. In conclusion, the numerical abnormalities of chromosomes 3 and 16, irrespective of gain or loss, may be characteristic of ACD-associated RCC.

Thymic Basaloid Carcinoma

Thymic carcinoma (primary carcinoma of the thymic epithelium; type C thymoma) is a rare malignancy. It usually presents in middle-aged to elderly patients and can exhibit a wide variety of morphologic appearances. Thymic basaloid carcinoma (thymic BC) is a particularly rare subtype, with less than 20 cases published in the English literature, mostly in the form of individual case reports. In this study, we present the clinicopathologic and immunohistochemical features of 12 new cases of thymic BC. There were 10 (83%) men and 2 (17%) women. Ages at the time of initial diagnosis ranged from 34 to 77 years (mean 55 y). The 2 most common manners of presentation were dyspnea on exertion (3 patients) and as an incidental finding on radiographic imaging (2 patients). Tumors ranged in size from 4.4 to 17 cm (mean 10.1 cm). One of 12 cases (8.3%) was associated with a multilocular thymic cyst. Immunohistochemistry was performed in 8 cases. Pan-cytokeratin was positive in all cases. CD117 (c-kit) was positive in 6 of 8 cases (75%), p63 was positive in 7 of 8 cases (88%), p53 was positive in 7 of 8 cases (88%), ranging from <10% to 90%, CD5 was focally positive in 3 of 8 cases (38%), collagen type IV was positive in 4 of 8 cases (50%), and proliferative index, as estimated by Ki67, ranged from <1% to approximately 15%. In 1 of 2 cases with sarcomatoid differentiation, Ki67 was greater than 80% in the sarcomatoid area. Cases were negative for thyroid transcription factor-1 (0 of 8), S-100 (0 of 7), and synaptophysin (0 of 7). Long-term data was available in 8 patients with an average follow-up of 30 months. Five patients died of their disease at an average of 34 months from the time of diagnosis. Of the remaining 3 patients, 1 had a stable recurrence and died at 4 years from unrelated causes, and 2 were alive without the evidence of disease at 12 and 7 months, respectively. Thymic BC, although previously regarded as a low-grade neoplasm, has shown that it is capable of aggressive behavior and significant mortality. In this paper, we review the pertinent literature and discuss the possible relationship of thymic BC with thymic adenoid cystic carcinoma, as well as BCs and adenoid cystic carcinomas at other sites.

Comparison of Different Clones (WT49 Versus 6F-H2) of WT-1 Antibodies for Immunohistochemical Diagnosis of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is known to mimic the morphology of a number of diverse neoplastic conditions. WT-1 protein is conventionally used as a positive mesothelioma marker. Recently, a new monoclonal antibody clone WT49 has recently become commercially available. To compare specificity and sensitivity of the conventionally used clone 6F-H2 for the diagnosis of MPM to those of the new clone WT49. Forty cases of MPM, and 55 cases of lung carcinoma, 10 cases of synovial sarcoma of the intrathoracic region were analyzed. Of the 40 cases of MPM tested, clone WT49 and 6F-H2 stained 30 (75.0%) and 26 (65.0%) cases, respectively. Nuclear staining of clone WT49 was observed in 4 (7.2%) cases of lung carcinomas and in 1 (10.0%) case of synovial sarcoma. However, there was no nuclear staining of clone 6F-H2 in lesions other than MPM. There was no cytoplasmic staining of clone WT49 in any tumor. However, cytoplasmic staining of clone 6F-H2 was observed in 7 (17.5%) cases of MPM, 17 (30.1%) cases of lung carcinomas, and 5 (50.0%) cases of synovial sarcoma. The main advantage of WT49 is its higher reactivity with the sarcomatoid area of biphasic mesothelioma, but the results also indicate 1 drawback, that this clone was seen to react with a small percentage of lung carcinomas when it is used to distinguish epithelioid mesotheliomas from lung carcinomas. Furthermore, the positive reaction of clone WT49 was restricted to nucleus without cytoplasmic staining, which is seen in conventionally used WT-1 antibodies.

Novel human breast cancer cell lines IBH‐4, IBH‐6, and IBH‐7 growing in nude mice

Breast cancer is the most frequent cancer in women. However, in vivo hormone receptor positive and metastatic models are scarce. The aim of the present manuscript was to assess if the novel steroid receptor positive human cell lines IBH-4, IBH-6, and IBH-7 developed in our laboratory from primary infiltrant ductal carcinomas are good models to study in vivo human breast cancer. Cell lines or tumors were inoculated to nude mice in the presence or absence of hormone supplementation. Growth was analyzed by ANOVA followed by Tukey-Kramer's test. Steroid hormone expression was assessed by immunohistochemistry and Western blotting. The histology of the tumors was analyzed. IBH-4 and IBH-6 cells were inoculated to nude mice and 100% of the injected mice developed tumors in the presence or absence of hormone treatment, although tamoxifen inhibited growth. IBH-4 and IBH-6 cell lines in vivo gave rise to poorly differentiated carcinomas with areas of solid growth and sarcomatoid areas showing no morphological signs of epithelial differentiation. Distinct features of malignancy were observed. IBH-7 tumors in animals receiving estradiol were semi-differentiated adenocarcinomas. IBH-7 cells grew only in the presence of estradiol, but even with hormone addition, the tumor take was 20%. These tumors metastasized to the uterus and lung and vascular tumor emboli were evident. IBH-7 tumors were invasive and able to break through the peritoneum. As a conclusion, IBH-4 and IBH-6 are good models for studying tumor progression, whereas IBH-7 is a good model for tumor take, being metastatic and strictly estrogen-dependent.

Case of Left Atrial Metastasis of a Sarcomatoid Carcinoma

Metastatic tumor involvement of the heart may occur with all types of primary neoplasms. Right atrial cardiac metastases following vena cava extension from renal cell carcinoma are well recognized, while a left atrial appearance is extremely rare. We report on a patient who developed a left atrial mass originating from the lower right pulmonary vein after successful resection of a renal cell carcinoma with sarcomatoid areas by right-sided nephrectomy. To our knowledge, this is the first described case of this type of pancytokeratin-expressing tumor in the literature so far.

Squamous Differentiation in a Sarcomatoid Chromophobe Renal Cell Carcinoma: An Unusual Case Report With Review of the Literature

We describe an extremely rare occurrence of a squamous differentiation in a sarcomatoid chromophobe renal cell carcinoma in a 45-year-old woman with nodal and lung metastasis at presentation. The tumor on histology showed all 3 components intimately admixed with each other, which to the best of our knowledge is the first such case to be reported in the literature. The renal pelvis was smooth walled and uninvolved. Kidney-specific cadherin was positive in the chromophobe renal cell carcinoma areas and negative in the sarcomatoid and squamous areas.

Squamous differentiation in a sarcomatoid chromophobe renal cell carcinoma: an unusual case report with review of the literature.

We describe an extremely rare occurrence of a squamous differentiation in a sarcomatoid chromophobe renal cell carcinoma in a 45-year-old woman with nodal and lung metastasis at presentation. The tumor on histology showed all 3 components intimately admixed with each other, which to the best of our knowledge is the first such case to be reported in the literature. The renal pelvis was smooth walled and uninvolved. Kidney-specific cadherin was positive in the chromophobe renal cell carcinoma areas and negative in the sarcomatoid and squamous areas.

Automated immunofluorescence analysis defines microvessel area as a prognostic parameter in clear cell renal cell cancer

Microvessel density (MVD) has been reported to have prognostic relevance for clear cell renal cell carcinoma (ccRCC). However, this finding is controversial because of the difficulty of MVD evaluation in this complex vascularized tumor type. The present study evaluates the use of an automated quantitative analysis (AQUA) system for objective and reproducible determination of tumor vascularization in clear cell renal cell carcinoma (ccRCC). The AQUA system was applied to tissue microarrays with 284 primary ccRCC tumors. To determine angiogenesis in ccRCC, we created an epithelial/stromal mask consisting of CD10, epithelial membrane antigen, and vimentin to distinguish epithelial tumor cells from CD34-positive endothelial cells. Using immunofluorescence and computer-aided quantification of CD34 expression, we measured the relative microvessel area (MVA) and compared the MVA to the manually counted MVD. The MVA determined by AQUA in a test set with 209 ccRCCs ranged from 0% to 30.3% (mean +/- SD, 10.1% +/- 6.3%). The manually determined MVD ranged from 6 to 987 vessels/mm(2) (416.8 +/- 252.8 vessels/mm(2)). MVA and MVD were significantly correlated (P < .001). A larger MVA was associated with histologic grade (P < .001), tumor stage (P =.008), presence of metastasis (P = .005), presence of sarcomatoid areas (P < .001), and tumor-specific survival (P < .001). Using MVA as defined in the test set, all associations with clinical and pathologic parameters were confirmed in a second independent validation set. MVA determination by AQUA is an objective and reliable method to quantify tumor vascularization in ccRCC. A large MVA correlates with a high MVD and is associated with better patient prognosis.

Expression of GLUT1 in Primary Renal Tumors

This study aimed to assess whether glucose transporter 1 (GLUT1) is useful in prognostication or differential diagnosis of renal tumors. GLUT1 immunostain for 228 renal tumors showed a membranous or cytoplasmic pattern. The membranous pattern was seen in 86.2% of 145 clear cell renal cell carcinomas (RCCs) and 100% of 11 transitional cell carcinomas (TCCs) but in no oncocytomas, other subtypes of RCC, or sarcomatoid areas of RCCs. The cytoplasmic pattern was seen in 55.2% of 145 clear cell RCCs, 38% of papillary RCCs (11/29), 13% of chromophobe RCCs (2/16), 22% of oncocytomas (5/23), and 82% of TCCs (9/11). Western blot showed a markedly increased GLUT1 protein content in clear cell RCCs compared with a low level in papillary RCCs and normal kidney specimens. GLUT1 expression in clear cell RCC was not significantly correlated with patient survival, tumor grade, or tumor stage. GLUT1 may be a novel target for immunotherapy and a useful marker in the differential diagnosis and classification of renal tumors.

Biphasic malignant mesothelioma cases with osseous differentiation and long survival: A review of the literature

This report describes two cases of diffuse biphasic malignant mesothelioma with osseous differentiation and long survival. Two male patients aged 66 and 54 years presented with chest pain, bloody pleural effusions, and diffuse and nodular pleural thickening. They both had a history of prolonged asbestos exposure. Sarcomatoid and epithelioid areas were identified on histopathological examination. In addition, there were foci of ossification. Epithelioid tumor cells as well as benign osteoclasts within the ossification reacted positively for cytokeratin 5/6, whereas sarcomatoid areas were negative. Both patients survived 39 and 69 months, respectively. To our knowledge, these two cases with biphasic malignant mesothelioma and osseous differentiation with long survival are the first to be described from Central Anatolia.

D2-40 and calretinin—a tissue microarray analysis of 341 malignant mesotheliomas with emphasis on sarcomatoid differentiation

AbstractAnti-calretinin antibodies are useful to differentiate adenocarcinomas from malignant mesotheliomas of the lung. Therefore, calretinin expression is rarely reported for sarcomatoid mesotheliomas. Anti-podoplanin antibodies (eg D2-40) react with lymphatic endothelia, Kaposi’s sarcoma, lymphangioma and mesotheliomas. For the interpretation of spindle cell lesions of the pleura, knowledge of calretinin and D2-40 expression frequencies in sarcomatoid mesothelioma is desirable. To systematically investigate the sensitivity of calretinin and D2-40 antibodies in epithelioid and sarcomatoid areas of malignant mesotheliomas, a tissue microarray with 341 malignant mesotheliomas, including 112 epithelioid, 46 sarcomatoid and 183 biphasic tumors was constructed. Epithelioid and sarcomatoid differentiated tumor areas were clearly separated within the tissue microarray. Expression of calretinin and D2-40 was separately studied in epithelioid and sarcomatoid areas by immunohistochemistry. Calretinin expression was found in 91% of epithelioid and 57% of sarcomatoid tumor areas. D2-40 immunostaining was present in 66% of the epithelioid and 30% of the sarcomatoid tumor areas. A combination of calretinin and D2-40 increased the sensitivity in epithelioid tumor areas to 0.96 and in sarcomatoid tumor areas to 0.66. These data indicate that a combination of calretinin and D2-40 will improve diagnostic accuracy for spindle cell lesions of the pleura, whereas almost all epithelioid mesotheliomas are identified by calretinin alone.

Malignant Mixed Tumor of Salivary Gland in a Dog

A tumor was observed in the left mandible of a 3-year-old male Shih-Tzu dog. Histopathology revealed neoplastic alveolar proliferation of round cells, sarcomatoid proliferation of round to spindle-shaped cells and an existing parotid gland tissue around the tumor. A cancellous bone framework was also seen throughout the tumor. The tumor cells in the sarcomatoid area were positive and weakly positive for vimentin and cytokeratin, respectively, demonstrating their myoepithelial character. We diagnosed this tumor as a malignant mixed tumor of the salivary glands, because of the location of the tumor, its invasiveness into the surrounding tissue and the identification of both epithelial and myoepithelial tumor cells.

Prostatic Adenosquamous Carcinoma Metastasizing to Testis

Adenosquamous carcinoma of the prostate is an unusual tumor with poor prognosis. Most arise after hormonal or radiotherapy of conventional prostatic adenocarcinoma. Sarcomatous transformation in them has been reported in only a few cases. Here, we present a unique case of “de novo prostatic adenosquamous carcinoma with focal sarcomatoid areas” that showed testicular metastasis, detected after scrotal orchiectomy.