Immunohistochemical markers in the differentiation of thymic and pulmonary neoplasms

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

CD70 in Thymic Squamous Cell Carcinoma: Potential Diagnostic Markers and Immunotherapeutic Targets

CD70 – a ligand protein of CD27 on lymphocytes – is expressed in a large spectrum of malignancies. It is an attractive target for antibody-based therapy and several clinical trials are currently being conducted. However, there is no evidence regarding the expression of CD70 and its relationship with expression of programmed death ligand-1 (PD-L1) and CD27+ tumor-infiltrating lymphocytes (TIL) in formalin-fixed paraffin-embedded (FFPE) tissues of thymic tumors. FFPE tissues of thymic squamous cell carcinoma (TSCC) (operative specimens, n = 31; biopsy specimens, n = 11), thymoma (n = 60), thymic carcinoid (n = 3), and lung squamous cell carcinoma (LSCC) (n = 30) were analyzed immunohistochemically. Immunoreactivity for CD70 was semi-quantitatively scored according to the proportion of positive tumor cells. Moreover, the densities of CD27-positive intratumoral TIL (iTIL) and stromal TIL of TSCC were assessed and survival was compared. Most TSCC cases (87%; 27/31) were CD70-positive. In contrast, all thymoma and thymic carcinoid cases were CD70-negative. In LSCC cases, CD70-positivity was significantly lower than TSCC cases (20%; 6/30). Biopsy and resected specimens obtained from the same patients demonstrated a consistent staining pattern (6/6 patients). The proportion of CD70-positive TSCC was comparable with those of CD5 (87%) and CD117 (90%). Correlation between CD70 and PD-L1 expression score was observed. There was no significant difference in survival between the CD70-high and CD70-low expression groups. Meanwhile, patients with CD27-positive iTIL-high tumors exhibited better survival than those with iTIL-low tumors. This tendency was weaker in the CD70-high subset. CD70 immunohistochemistry is useful in diagnosing TSCC. CD70 may prevent anti-tumor immunity via CD27. Immunotherapy targeting the CD70–CD27 axis may be a promising option for the treatment of TSCC.

Thymic Lymphoepithelial Carcinoma Associated with Epstein-Barr Virus: Experiences and Literature Review

Thymic lymphoepithelial carcinoma (TLEC) is a primary thymic carcinoma that accounts for about 14% of all thymic epithelial tumors and is classified into 14 types. The histological morphology is similar to lymphoepithelioma, a type of undifferentiated nasopharyngeal carcinoma. It has been reported that squamous carcinoma accounts for approximately 80% of thymic carcinoma, followed by TLEC, which accounts for 6%. TLEC has been reported to be associated with Epstein-Barr virus (EBV), with EBV infection in TLEC tumor cells first noted by Lyvraz et al. in 1985. Tumors shown to be EBV-positive are classified as TLEC if lymphoplasmacytic infiltration is lacking. However, only about 50% of the cases are positive for EBV, which is lower compared to nasopharyngeal lymphoepithelioma. Instances of EBV infection in other types of thymic epithelial tumor have been reported at lower rates, which suggests that EBV infection may have an important influence on the carcinogenesis of TLEC, though the etiology is unknown. TLEC is a highly malignant tumor with poor prognosis, as affected patients have a median survival time of 22 months, according to 58 cases from the literature, while the 5-year survival rate is 34.4%. Presently, prognosis is not considered to be affected by the presence or absence of EBV positivity.

Pulmonary Sarcomatoid Carcinomas: A Review

Pulmonary sarcomatoid carcinomas belong to a group of neoplasms that remain incompletely understood. They are rare tumors of the bronchopulmonary system that incorporate a wide range of neoplasms that by definition contain a sarcomatoid component characterized by spindle or giant cells. Such classification has led to a heterogenous tumor category that includes neoplasms with different clinical, morphologic, and prognostic features. To date, the histopathologic diagnosis of pulmonary sarcomatoid carcinomas does not require the use of ancillary testing and is based on light microscopic criteria alone. However, with recent advances in immunohistochemical and molecular methods, it is becoming increasingly clear that pulmonary sarcomatoid carcinomas represent poorly differentiated or "dedifferentiated" variants of conventional non-small cell carcinomas with similar immunophenotype and molecular signatures. This review summarizes the latest insights and concepts of these unusual tumors and outlines future directions with emphasis on tumor classification and patient management.

An immunohistochemical panel consisting of EZH2, C-KIT, and CD205 is useful for distinguishing thymic squamous cell carcinoma from type B3 thymoma

Type B3 thymoma and thymic squamous cell carcinoma (SqCC) often cause a diagnostic problem due to their histological similarities. The aim of this study is to identify EZH2 as a novel and powerful biomarker that can effectively distinguish thymic SqCC from type B3 thymoma, and find optimal combinations among 11 markers. A total of 53 patients, comprising 26 with type B3 thymoma and 27 with thymic SqCC, were allocated to the discovery or validation cohorts, and immunohistochemical staining was performed and analyzed. The expression level of each marker was scored, and receiver-operator characteristic curve analysis was performed to evaluate their diagnostic accuracies. This analysis identified EZH2, C-KIT, and CD205 as useful markers for distinguishing thymic SqCC, and a combined panel approach using them further improved diagnostic accuracy in both the discovery and validation cohorts. In the combined cohorts analysis, EZH2 was the single best marker with 88.9% sensitivity and 100% specificity [area under the curve (AUC) = 0.967]. The sensitivity and specificity were 85.2% and 100% (AUC = 0.962) for C-KIT, and 100% and 73.1% (AUC = 0.844) for CD205. The combined panel had the highest sensitivity and specificity at 96.3% and 100%, which was significantly or marginally higher than those of EZH2, C-KIT, and CD205 alone (P = 0.071, 0.034, and 0.005, respectively). The present findings indicate that EZH2 is useful as a novel diagnostic marker for distinguishing thymic SqCC and that the panel approach can be used as an effective differential diagnostic tool in daily practice.

Rare cause of atrial fibrillation: a thymic mass

A 62-year-old African-American man admitted to the emergency room with chest pain and exertional dyspnoea. He was found to be in rapid atrial fibrillation with pulmonary oedema. A transoesophageal echocardiogram performed prior to cardioversion showed a depressed left ventricular function (ejection fraction 30%) and an extracardiac heterogeneous echodensity compressing the right atrium and the superior vena cava. CT of the chest confirmed an anterior mediastinal mass measuring 13.5×6.6×10.1 cm, exerting a mass effect on the right atrium with mediastinal and right hilar adenopathy. CT-guided biopsy of the mediastinal mass revealed thymic carcinoma (squamous cell subtype). The metastatic workup was negative. The mass was deemed surgically unresectable due to its proximity to the heart. Chemotherapy was initiated with carboplatin/paclitaxel every 3 weeks with plans for intensity modulated radiotherapy after one to two cycles of chemotherapy. The patient recently had a repeat CT scan of the chest showing regression of the tumour.

Thymoma and thymic carcinomas

Thymomas (Ts) and thymic carcinomas (TCs) are rare tumours of the mediastinum with an incidence rate of 1.7/million per year in Europe. Histological classification is based on rate of non-malignant-appearing thymic epithelial cells and proportions of lymphocytes (A, AB, B1, B2, B3, and C), while staging system concerns localisation of the involved areas. Surgery is the mainstay of treatment with a 10-year survival of 80%, 78%, 75%, and 42% for stages I, II, III and IV, respectively, with an R0 resection. Radiotherapy has a role in selected cases (stage III patients or R1-2 residual) and platinum-based chemotherapy remains the standard of care for patients with advanced disease. A multimodality approach would be advisable when surgery is not recommended. Since molecular aberrations are poorly understood and few responses are reported, targeted therapies are yet being studied. In this review, we describe key aspects of clinical management for Ts and TCs.

Differential diagnostic value of CD5 and CD117 expression in thoracic tumors: a large scale study of 1465 non-small cell lung cancer cases

Background

Thoracic pathologists are frequently faced with tissue specimens from intrathoracic/mediastinal tumors. Specifically the differentiation between thymic and pulmonary squamous cell carcinomas (SqCC) can be challenging. In order to clarify the differential diagnostic value of CD5 and CD117 in this setting, we performed a large scale expression study of both markers in 1465 non-small cell lung cancer (NSCLC) cases.

Methods

Tissue microarrays of formalin-fixed paraffin-embedded resection specimens of 1465 NSCLC were stained with antibodies against CD117 and CD5. Positivity of both markers was correlated with clinicopathological variables.

Results

CD117 was positive in 145 out of 1457 evaluable cases (9.9 %) and CD5 was positive in 133 out of 1427 evaluable cases (9.3 %). 28 cases (1.9 %) showed coexpression of CD117 and CD5. Among the 145 cases that were positive for CD117, 97 (66.8 %) were adenocarcinomas (ADC), 34 (23.4 %) were SqCC, 5 (3.4 %) were adenosquamous carcinomas (ADSqCC), 8 (5.5 %) were large cell carcinomas (LC), and one (0.6 %) was a pleomorphic carcinoma (PC). In the CD5 positive group consisting of 133 cases, 123 (92.4 %) were ADC, 0 (0 %) were SqCC, 4 (3.0 %) were ADSqCC, 3 (2.2 %) LC and 3 (2.2 %) were PC. None of the 586 SqCC showed expression of CD5. No association of CD117- or CD5 positivity to patients’ age, pathological stages or to T-, N-, or M- categories was observed.

Conclusions

A substantial subset of NSCLC exhibit positivity of CD117 and CD5. Since CD5 expression was not observed in pulmonary SqCC, but is expressed in the majority of thymic squamous cell carcinomas, the application of this immunomarker is a valuable tool in the differential diagnosis of thoracic neoplasms.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-015-0441-7) contains supplementary material, which is available to authorized users.

Immunohistochemistry in the diagnosis of thymic epithelial neoplasms

The diagnosis of thymic epithelial neoplasms is normally rendered after careful evaluation of their histologic features. In some cases, however, the morphological heterogeneity or overlap with neoplasms of other organ systems can lead to diagnostic uncertainty. On the basis of this, the use of immunohistochemical stains as a diagnostic adjunct has become a popular tool. Although undoubtedly, immunohistochemistry has its role in the diagnosis of difficult cases, to date there are no specific markers that would distinguish thymic epithelial neoplasms from other tumors and interpretation of immunohistochemical results should only ever be made in conjunction with accurate morphologic analysis and careful clinical evaluation. This article will review the current knowledge of the immunohistochemical phenotype of thymic epithelial neoplasms with particular emphasis on its use for diagnostic purposes and the latest advances in this field.

Value of thyroid transcription factor-1 immunostaining in tumor diagnosis: a review and update

Thyroid transcription factor-1 (TTF-1) is a tissue-specific transcription factor that plays a critical role in the normal development of embryonic epithelial cells of the thyroid and lung. Because TTF-1 expression is highly restricted to epithelial tumors arising in these organs, it is, at present, one of the immunohistochemical markers most commonly used to assist in the differential diagnosis of carcinomas of the lung and thyroid. Recent studies, however, have reported that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought as it can be found to be expressed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Even though this unexpected TTF-1 positivity has been reported more frequently with the recently available SPT24 anti-TTF-1 monoclonal antibody, it has also been shown to occur with the commonly used 8G7G3/1 clone, albeit in a lower percentage of cases. Despite these findings, TTF-1 remains a very useful immunohistochemical marker in diagnostic pathology.

Thymic carcinoma, part 1: a clinicopathologic and immunohistochemical study of 65 cases

The clinicopathologic and immunohistochemical features of 65 primary thymic carcinomas are reported (43 men and 22 women; 19-81 years old). Thymectomy was performed in all cases. Masaoka staging for 53 patients showed 3 patients in stage I, 14 in stage II, 17 in stage III, and 19 in stage IV. Histologic studies revealed 9 carcinoma subtypes. Immunohistochemically, the tumors showed high rates of expression for cytokeratin, Pax8, and FoxN1. Follow-up for 62 patients revealed that 36 patients were alive (mean follow-up, 51.1 months) and 26 had died (mean survival, 47.5 months). The 3- and 5-year overall survival rates were 76.6% and 65.7%, respectively. Our findings suggest that thymic carcinomas may behave less aggressively than commonly believed. Lymph node status and tumor size seem to be important prognostic factors. The Masaoka staging system does not seem to reliably predict outcome.

Respiratory Tract and Mediastinum

Normal cytology, abnormal and atypical cells, non-cellular components, and infectious cell changes are largely described together with benign, malignant, and neuroendocrine lesions regarding exfoliative and aspiration cytology of the lung. A separate section broadly addresses diagnostic findings and differential diagnoses in bronchoalveolar washings.

The section ‘Fine needle aspiration biopsy of mediastinal disorders’ covers in particular biopsy techniques, accuracy of liquid-based cytology, and the complex lesions of the thymus gland. Cytodiagnostic algorithms of the major benign and malignant pulmonary and mediastinal lesions and their respective differential diagnoses are additionally presented in synoptic setups.

Fascin expression in dendritic cells and tumor epithelium in thymoma and thymic carcinoma

The majority of thymomas are histologically characterized by tumor-infiltrating lymphocytes. Mature dendritic cells (DCs) are known to assemble lymphocytes through antigen presentation to T lymphocytes. Fascin, a 55-kDa actin-binding protein and a known marker for mature DCs, regulates filaments necessary for the formation of filopodia in cell migration. Moreover, fascin expression in various epithelial neoplasms has recently been reported to be associated with invasion of tumor cells and clinically aggressive manifestations. In the present study, we investigated fascin expression immunohistochemically in tissues of thymomas and thymic carcinomas surgically resected at our institute. A total of 34 thymomas and 5 thymic carcinomas were included. The amount and immunohistochemical intensity of both fascin(+) DCs and tumor epithelium were counted and assessed, and the clinicopathological data were also scored. Statistical analyses revealed that the amount of fascin(+) DCs with the formation of clusters was associated with lymphocyte-rich variants (p=0.002) and cortical differentiation (p=0.037) of thymoma with complication from myasthenia gravis (p=0.002). The quantity of fascin(+) epithelium was associated with a strong intensity of fascin in infiltrating DCs (p=0.002) with the formation of clusters (p=0.002) and favorable prognosis, as assessed by the Masaoka staging system (p=0.001). The amount of infiltrating DCs (p=0.024) and fascin(+) epithelium were lower in thymic carcinoma. It was concluded that fascin(+) epithelium may induce tumor immunity through the surveillance activity of fascin(+) DCs in thymic neoplasms, thus improving prognosis.

Tumour eosinophilia combined with an immunohistochemistry panel is useful in the differentiation of type B3 thymoma from thymic carcinoma

It is sometimes difficult to differentiate between type B3 thymoma from thymic carcinoma histologically. Given the rarity of these tumours, studies have been limited. A series of 66 thymic neoplasms were reviewed and classified according to the World Health Organization (WHO) scheme. We performed a tissue microarray analysis of surgically resected thymic tumour specimens including 12 thymic carcinomas, 17 type B3 thymomas and 37 thymomas of other types. Percentage and staining intensity of immunohistochemical markers were recorded. Tumour eosinophilia was recorded positive if at least one eosinophilic cell identified. Positive staining of the following markers significantly differentiated type B3 thymoma from thymic carcinoma: cytokeratin 5/6 (15 vs. 3), Mesothelin (0 vs. 5), cytoplasmic androgen receptor (10 vs. 0), CD57 (9 vs. 0), CD5 (0 vs. 7), TdT (lymphocytic) (14 vs. 1), CD1a (lymphocytic) (14 vs. 2), CD117 (1 vs. 9), MOC31 (2 vs. 6), p21 (2 vs. 8), cytoplasmic Survivin (0 vs. 4), and tumour eosinophilia (1 vs. 11). Combining two or three markers was able to differentiate these two tumours with area under the curve percentage of at least 92%. Tumour eosinophilia combined with a panel of immunohistochemistry could differentiate type B3 thymoma from thymic carcinoma.

Immunohistochemical differential diagnosis between thymic carcinoma and type B3 thymoma: diagnostic utility of hypoxic marker, GLUT-1, in thymic epithelial neoplasms

There are only a few immunohistochemical markers that are useful for differentiating thymic carcinomas from type B3 thymomas. The purpose of this study is to examine the additional markers that would be useful for differentiating between thymic carcinoma and thymoma type B3. We performed a tissue microarray analysis of surgically resected thymic tumor specimens from 12 cases of thymic carcinoma, 7 cases of type B3 thymoma, and 68 cases of other types of thymoma. Immunostaining using 49 antibodies was scored based on staining intensity and the percentage of cells that stained positive. Seven proteins that were selected by the staining scores, namely, GLUT-1 (167 vs 4), CA-IX (110 vs 15), c-kit (162 vs 44), CD5 (33 vs 0), MUC-1 (54 vs 0), CEA (42 vs 0), and CK18 (110 vs 42), were significantly higher in the thymic carcinomas than in the type B3 thymomas. The staining sensitivity and specificity of the antibodies for thymic carcinoma were GLUT-1, sensitivity 72% and specificity 100%; CA-IX, 58 and 71%; c-kit, 72 and 85%; CD5, 33 and 100%; CK18, 58 and 71%; MUC-1, 25 and 100%; and CEA, 33 and 100%. Glucose transporter 1 (GLUT-1) is the best marker for thymic carcinoma because it had the highest sensitivity and specificity. Positive immunostaining for a combination of three markers, namely, GLUT-1, CD5, and CEA, enabled differentiation of thymic carcinoma with 91.6% sensitivity and 100% specificity. In conclusion, we identified GLUT-1 as an additional marker that will be useful for differentiating thymic carcinoma from type B3 thymoma, especially in biopsy specimens that have been crushed or are otherwise difficult to examine morphologically in thymic tumors.

Transcription expression and clinical significance of TTF-1 mRNA in pleural effusion of patients with lung cancer

The aim of this study was to evaluate diagnostic utility of thyroid transcription factor 1 (TTF-1) mRNA in pleural effusions (PEs) of patients with lung cancer, especially primary pulmonary adenocarcinoma (PPA). Transcription levels of TTF-1 were detected by reverse transcription polymerase chain reaction (RT-PCR) in PEs of patients with lung cancer (56 cases) and with lung benign diseases (44 cases). The expression rate of TTF-1 mRNA was significantly higher in PEs of patients with lung cancer (73.2%) than with benign lung diseases (0%). In subclasses, the expression rate of TTF-1 mRNA was obviously higher in PEs of patients with PPA (93.0%) than with metastatic pulmonary adenocarcinoma (0%) and with primary pulmonary squamous cell carcinoma (12.5%). When compared with immunocytochemistry and cytology, TTF-1 mRNA gave the best diagnostic performance in diagnosing PPA: sensitivity of 93.0%, specificity of 100%, and accuracy of 96.6%, respectively. As a molecular marker of detecting pleural micrometastasis, TTF-1 mRNA may be helpful to diagnose the cancer cells in PEs of patients with lung cancer, especially with PPA.

Thymic tumor with adenoid cystic carcinomalike features: a clinicopathologic study of 4 cases

Thymic carcinomas are rare malignant neoplasms which comprise several histologic subtypes. Adenoid cystic carcinoma (ACC) is included among these subtypes even if it has never been formally reported. We evaluated the clinical, radiologic, morphologic, immunohistochemical, and genetic features of 4 cases of thymic neoplasms with ACC-like features retrieved from the authors' consult files. Most cases affected adult/elderly males (mean 68.5 y; range: 63 to 77 y; M:F ratio=3:1), and were asymptomatic. The clinical history (no evidence of ACC in other sites), radiologic findings (a mass in the thymic region), and morphologic features (residual thymic tissue at the periphery of the neoplasm) strongly supported their primary thymic nature. Grossly, most of the tumors presented as multicystic lesions. On microscopic examination there were true glandular spaces filled with periodic acid-Schiff+material, and pseudocysts containing stromal mucin, collagen IV, and laminin. Features favoring malignancy were overtly infiltrative margins (2/4), mitotic figures (2/4), cytologic atypia (1/4), vascular invasion (1/4), absence of organoid thymuslike pattern (4/4), and absence of immature (TdT+) T lymphocytes (3/3). Necrosis and nerve invasion were not observed. The tumor cells showed the following immunophenotype: p63+(3/3), CK34betaE12+(3/3), CD5+ in scattered cells (1/3), CD117- (3/3), chromogranin-(2/2), synaptophysin-(2/2), and CD56- (2/2). MIB-1 ranged from 1% to 10%. Comparative genomic hybridization revealed an isolated gain of chromosome 8 in 1/3 cases. One patient is alive and well after 20 months, 1 died of another cause 5 years later, and 2 were lost at follow-up. Exceptionally, primary thymic tumors may exhibit histologic features resembling those of ACC of salivary glands. They may be well circumscribed and cytologically bland or invasive and cytologically atypical. In either case they lack an organoid thymuslike pattern and immature T lymphocytes. We have interpreted them as a microscopic subtype of well-differentiated thymic carcinoma of low-grade malignancy, an impression supported by the admittedly limited follow-up information.

Thymic carcinoma: update of current diagnostic criteria and histologic types

Thymic carcinomas are rare tumors thought to derive from thymic epithelium. Because of the complex embryological origin of the thymus, whose development includes contributions from the third and, to a lesser extent, the fourth pharyngeal pouches, thymic carcinomas are endowed with great morphologic heterogeneity. A large number of histologic types have been described that resemble tumors arising in other organs. Unfortunately, no definitive pathognomonic histological features or immunohistochemical markers are associated with these tumors, making them a real challenge for diagnosis. Because of their close similarity with tumors arising at other organs, the diagnosis of thymic carcinoma must be regarded, for the most part, as a diagnosis of exclusion. This review will focus on current criteria for diagnosis of these tumors, with a review of the various histopathologic appearances that they can adopt.

The diagnostic utility of immunohistochemistry in distinguishing between epithelioid mesotheliomas and squamous carcinomas of the lung: a comparative study

As both mesotheliomas and squamous carcinomas can present a wide variety of morphological patterns, they can on occasion be confused. Recently, some groups of investigators have called attention to the difficulties that sometimes exist in distinguishing between these malignancies and the need to define a panel of markers that can assist in reaching the correct diagnosis. The aim of the present study is to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and squamous carcinoma of the lung. A total of 30 epithelioid pleural mesotheliomas exhibiting a solid or predominantly solid pattern, and 30 nonkeratinizing squamous carcinomas of the lung were investigated for the expression of the following markers: podoplanin, calretinin, mesothelin, WT1, keratin 5/6, keratin 7, p63, carcinoembryonic antigen (CEA), MOC-31, Ber-EP4, B72.3, BG-8 (Lewis(y)), leu-M1 (CD15), and thyroid transcription factor-1 (TTF-1). All 30 (100%) of the mesotheliomas reacted for calretinin, mesothelin and keratin 7, 93% each for podoplanin, WT1 and keratin 5/6, 13% for Ber-EP4, 7% each for p63, MOC-31 and BG-8, and 0% for B72.3, CEA, leu-M1 and TTF-1. All 30 (100%) of the squamous carcinomas were positive for p63 and keratin 5/6, 97% for MOC-31, 87% for Ber-EP4, 80% for BG-8, 77% for CEA, 57% for keratin 7, 40% for calretinin and B72.3, 30% for leu-M1, 27% for mesothelin, 15% for podoplanin, and 0% for WT 1 and TTF-1. After analyzing the results, it is concluded that from a practical point-of-view, a combination of two positive mesothelioma markers (WT1 and calretinin or mesothelin) with two negative mesothelioma markers (p63 and MOC-31) would allow the differential diagnosis to be established between epithelioid mesotheliomas and squamous carcinomas of the lung in nearly all instances.

Malignant thymoma associated with mixed connective tissue disease: a case report

Many autoimmune diseases have been reported to be associated with malignancy. Mixed connective tissue disease (MCTD), however, has rarely been associated with malignancy. Thymoma is one of the neoplasms often reported to be related to various immunological disorders. Among the types of thymoma defined by WHO, malignant thymoma (thymoma type C) is the one least reported to be associated with autoimmune disease. Here, we report a case of malignant thymoma with concurrent MCTD, which manifested with acrosclerosis, Raynaud's phenomenon, arthritis (synovitis), and a high titer of anti-ribonucleoprotein antibody.

Utility of CD10 and RCCma in the diagnosis of metastatic conventional renal-cell adenocarcinoma by fine-needle aspiration biopsy

The cytologic diagnosis of primary conventional renal-cell adenocarcinoma (cRCC) is usually straightforward; however, metastatic cRCC must be distinguished from a variety of neoplasms with clear-cell features. CD10, a cell membrane-associated neutral endopeptidase, and renal-cell carcinoma marker (RCCma), an antibody against human proximal tubular brush border antigen, have recently been shown to be useful in the diagnosis of cRCC. We compared CD10 and RCCma in cell block material from fine-needle aspiration biopsies (FNABs) to assess their utility in the diagnosis of metastatic cRCC, in cytologic specimens. Seven primary and sixteen metastatic cRCCs were immunostained with CD10 and RCCma. The immunoreactivity results were compared with those of a variety of neoplasms originating from other sites such as the liver, lungs, breast, and the gastrointestinal tract. The sensitivity and specificity of CD10 for cRCC were 100% and 59%, respectively. The sensitivity and specificity of RCCma for cRCC were 35% and 100%, respectively. We conclude that CD10 has limited value in confirming the diagnosis of cRCC because of its low specificity. RCCma, when positive, is highly specific for cRCC, but its low sensitivity hinders its diagnostic usefulness.

Histopathologic classification of lung cancer: Relevance of cytokeratin and TTF-1 immunophenotyping

Histopathologic classification of lung carcinoma is important, as a prognostic factor and in the evaluation of treatment modalities. Although the World Health Organization classification of lung cancer is based on routine microscopy, immunohistochemistry is an important additional aspect in modern pathologic practice. This study examines whether the main histologic types of lung carcinomas are more reliably diagnosed with immunohistochemical technique using antibodies for the lung tissue-specific antigen thyroid transcription factor-1 (TTF-1) and a panel of cytokeratin (CK) antibodies. Forty-five cases of lung cancer (12 squamous cell carcinoma, 13 small cell carcinoma, 11 adenocarcinoma, 9 large cell carcinoma [LCC]/pleomorphic carcinoma) were stained with antibodies to CK CAM5.2, CK5, CK7, CK20, and TTF-1. All 45 cases were positive with CAM5.2, 16 of 45 cases with CK5, 34 of 45 cases with CK7, 4 of 45 cases with CK20, and 29 of 45 with TTF-1. Squamous cell carcinoma (epidermoid carcinoma) had the immunophenotype CK5+/TTF-1-, and at least 20% were also positive with CK7. Most nonepidermoid tumors had the "lung-specific" phenotype CK5-/TTF-1+; all small cell carcinomas had the phenotype CK5-/CK8+/TTF-1+, all adenocarcinomas CK5-/CK7+/TTF-1+ and (more than 50%) of LCC CK5-/CK7+/TTF-1+. Thus, more than 50% of LCCs were of the same phenotype as adenocarcinomas. The immunophenotypes of the main histologic types of lung carcinoma are stable and highly reproducible. However, because of considerable overlapping, immunophenotyping should not be used alone for histopathologic classification of lung cancer, but only as an adjunct to light microscopy. It is also suggested that CK5+ lung carcinomas with basaloid features should be regarded as variants of squamous cell carcinoma and not as LCC.

[Primary non-lymphoid thymic neoplasms. A study of 58 cases]

BACKGROUND AND OBJECTIVE

Primary non-lymphoid thymus tumors (PNLTT) are an uncommon though quite varied pathology. Our objective was to identify the clinical, therapeutic and histologic variables with a prognostic value in these neoplasms.

PATIENTS AND METHOD

We studied 58 PNLTT cases, corresponding to 52 epithelial neoplams (PTEN), 4 thymolipomas (7%) and 2 neuroendocrine tumors (3%). Commonest clinical manifestations were myasthenia gravis (41%) and dyspnea (21%). Three patients were symptom-free (24%). We used Kaplan-Meier survival curves and Cox regression model.

RESULTS

All patients underwent surgery which consisted of thymectomy. Four patients underwent a biopsy procedure alone. Perioperative mortality was 3% (n = 2) and morbidity was 31% (n = 18), mainly because of respiratory and wound problems. 24 patients with PTEN, Masaoka degrees III and IV, and a patient with a lymphoepithelial carcinoma received adjuvant chemotherapy and/or radiotherapy. With a follow-up of 13 + 5 years, 12 PTEN patients and one patient with a neuroendrocrine tumor died as a consequence of the evolution of the disease. Cumulative survival was 80% at 5 years, 71% at 7 years and 63% at 10 years. There are currently two local relapses in two PTEN cases after 9 and 8 years of follow-up, respectively. Main prognostic factors are the histologic type and subtype and the clinical stage (p < 0.001).

CONCLUSIONS

In PNLTT early diagnosis is crucial in order to administer a correct treatment before the clinical stage is more advanced. Main prognostic factors are the histologic type and subtype and the clinical stage.