Adenocarcinoma simulating mesothelioma: a clinicopathologic and immunohistochemical study of 29 cases

Immunocytochemistry of effusions: Processing and commonly used immunomarkers

Definitive cytopathological interpretation of some of the effusion fluids may not be possible based on cytomorphological evaluation alone. As discussed in other reviews, this is due to various reasons specifically applicable to effusion fluids including remarkably wide morphologic spectrum of reactive mesothelial cells overlapping with some well to moderately differentiated metastatic carcinoma. The challenge is subject to various factors including level of interpreter training or experience, institutional demographics (such as type of prevalent diseases, predominant sex and age group), technical advances in ancillary support, and expertise in cytopreparatory processing. In such cases immunohistochemistry performed on cell-block sections is simple objective adjunct with or without other ancillary techniques. Ongoing increase in number of immunomarkers along with rabbit monoclonal antibodies with relatively higher affinity is further refining this field. SCIP (subtractive coordinate immunoreactivity pattern) approach, discussed as separate dedicated review article, facilitates refined interpretation of immunoreactivity pattern in coordinate manner on various serial sections of cell-blocks. However, many variables such as delay after specimen collection, specimen processing related factors including fixation and storage; ambient conditions under which paraffin blocks are archived (for retrospective testing); antigen retrieval method; duration of antigen retrieval step; antibody clone and dilution; and antibody application time are common with application of immunohistochemistry in other areas. This review is dedicated to highlight technical aspects including processing of effusion specimens for optimum immunocytochemical evaluation along with commonly used immunomarkers in effusion cytopathology. This review focuses on the technical and general information about various immunomarkers.

Inflammatory Lesions Mimicking Chest Malignancy: CT, Bronchoscopy, EBUS, and PET Evaluation From an Oncology Referral Center

Infective and inflammatory diseases can mimic malignancy of the lung. Granulomatous inflammations are common causes of pulmonary nodule, mass, or nodal disease. Systemic infection or inflammation also commonly involves the lung that may raise suspicion of a malignant process. Even in patients with a known malignancy, inflammatory diseases can simulate new metastasis or disease progression. Knowledge of the imaging features of these diseases is essential to prevent missed or overdiagnosis of malignancy. Radiologists also need to be familiar with the scope and limitations of bronchoscopy, endobronchial ultrasound, PET-CT, and biopsy to guide clinical management. In this review, we discuss the imaging features and diagnostic approach of common mimickers of chest malignancy that involve the chest wall, pleura, lung parenchyma, and mediastinal nodes.

The forensic significance of pseudomesotheliomatous adenocarcinoma of the lung

Pseudomesotheliomatous carcinomas (PMC) are rare tumors that clinically, macroscopically, and sometimes histologically resemble malignant pleural mesotheliomas. We report a case of a 91 year woman who was found to have diffuse nodular pleural thickening and a lung mass during a workup for persistent cough. She declined rapidly and died before a histologic diagnosis could be made. Postmortem examination revealed a tumor that diffusely involved the pleural surface with local extension into the chest wall, pericardium, and diaphragm along with a concurrent lung mass. Histologic examination showed poorly-differentiated cells predominantly arranged in sheets, cords, and nests with focal glandular differentiation. An immunohistochemical panel of calretinin, WT1, BEREP4, MOC31, and TTF1 confirmed the diagnosis of primary lung adenocarcinoma. The macroscopic, histologic, and immunohistochemical features used to distinguish metastatic and primary lung adenocarcinoma from epithelioid malignant mesothelioma are discussed. The distinction of malignant mesothelioma from pseudomesotheliomatous carcinoma is important for medicolegal reasons regarding asbestos related compensation claims.

Pseudomesotheliomatous Type of Sarcomatoid Squamous Cell Lung Cancer Presenting With Hemothorax

A 44-year-old man presented with spontaneous massive hemothorax. Computed tomographic scan revealed thickened and nodular pleura with no evidence of lung tumor. The patient underwent right open total pleurectomy. Histopathologic and immunohistochemical studies of the pleura confirmed poorly differentiated sarcomatoid squamous cell carcinoma of the lung with metastasis to the pleura. The carcinoma was psuedomesothelimatous type because of its presentation as diffuse pleural thickening. This presentation of sarcomatoid cancer as pseudomesotheliomatous type with massive hemothorax is rare and can be considered as a differential diagnosis in diffuse pleural thickening or hemothorax, especially in the absence of a clinically identifiable primary lung tumor.

Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma

AIMS

The aims of this study were to clarify the usefulness of immunohistochemistry in the differential diagnosis of epithelioid mesothelioma with a solid growth pattern [solid epithelioid mesothelioma (SEM)] and poorly differentiated squamous cell carcinoma (PDSCC), and to confirm the validity of a specific type of antibody panel. Additionally, we aimed to clarify the pitfalls of immunohistochemical analyses.

METHODS AND RESULTS

Formalin-fixed paraffin-embedded specimens from 36 cases of SEM and 38 cases of PDSCC were immunohistochemically examined for calretinin, podoplanin (D2-40), Wilms' tumour gene product (WT1), cytokeratin (CK) 5/6, p40, p63, carcinoembryonic antigen (CEA), epithelial-related antigen (MOC31), claudin-4, thyroid transcription factor-1 (TTF-1), and napsin A. WT1 showed the highest diagnostic accuracy (85.1%) as a mesothelial marker, and CEA, p40 and claudin-4 showed higher diagnostic accuracies (95.9%, 94.6%, and 93.2%, respectively) as carcinoma markers. Calretinin (diagnostic accuracy: 75.7%), D2-40 (diagnostic accuracy: 67.6%), CK5/6 (diagnostic accuracy: 63.5%), TTF-1 (diagnostic accuracy: 55.4%) and napsin A (diagnostic accuracy: 52.7%) could not differentiate between SEM and PDSCC. Among these markers, the combination of calretinin and WT1 showed the highest diagnostic accuracy (86.5%) as a positive marker, and the combination of p40 and CEA showed the highest diagnostic accuracy (97.3%) as a negative marker. The combination of CEA and claudin-4 also showed relatively high diagnostic accuracy (94.6%) as a negative marker.

CONCLUSIONS

We recommend the combination of WT1 and calretinin as a positive maker, and the combination of CEA and claudin-4 as a negative marker, for differential diagnoses of SEM and PDSCC.

Fatal hemothorax caused by pseudomesotheliomatous carcinoma of the lung

We present a case of a poorly differentiated pseudomesotheliomatous carcinoma originating in the lung, which was manifested with the distinctly rare complication of massive true hemothorax and persistent blood loss that proved rapidly fatal in spite of surgery. Pseudomesotheliomatous carcinoma of the lung and neoplasia-associated hemothorax are reviewed and discussed.

Pathology of mesothelioma

The incidence of mesothelioma has been gradually increasing in Japan, and the underlying factor for this is considered to be the increase in the amount of asbestos imported into Japan between 1960 and 1975. Mesothelioma can be roughly divided into localized and diffuse types, but the former is extremely rare. In making a diagnosis of mesothelioma, it is important to confirm the location of tumor and the specific gross findings before histological examination. Mesothelioma can be categorized histologically as epithelioid type, sarcomatoid type, biphasic type, desmoplastic type, among others. It can take many forms; consequently, there are many diseases to be differentiated when the diagnosis of mesothelioma is based on histological analyses. Immunohistochemical stains are useful for making a diagnosis, but the correct combination of antibodies as positive or negative markers should be selected and a comprehensive assessment of the staining results is necessary. The accuracy of the pathological diagnosis is very important to the patients because they can be receive official compensation or relief when the diagnosis of mesothelioma is confirmed. Under present conditions, both clinicians and pathologists must make a concerted effort to improve the accuracy of the diagnosis of mesothelioma.

Malignant mesothelioma: current status of histopathologic diagnosis and molecular profile

Malignant mesothelioma of the pleura is a relatively rare neoplasm that has been estimated to account for 20 deaths per million males per year in North America and Europe. A causative association has been well established with asbestos exposure. Paradoxically, the incidence of this tumor continues to rise despite public efforts to reduce, contain or eliminate exposure to asbestos fibers over the past few decades. Another paradoxical feature of the disease is that the majority of malignant mesotheliomas represent morphologically low-grade, well-differentiated neoplasms, yet they follow a relentlessly aggressive and virtually uniformly fatal outcome. For this reason, identification of clinical, morphologic, immunohistochemical or molecular genetic parameters is of extremely limited value for prognostication. Surprisingly, for a disease that currently has no known cure, one of the major problems still lies in establishing the correct diagnosis. Diagnosis acquires a particular relevance in light of the medicolegal ramifications of this disease, and diagnosis of malignant mesothelioma is still fraught with difficulties. Despite the advances in modern diagnostic techniques, no specific markers or morphologic features exist that are exclusive to these tumors. Herein, the current status of malignant mesothelioma diagnosis is reviewed, including the possible contributions of modern molecular techniques for their diagnosis.

Systemic sclerosis and pseudomesotheliomatous adenocarcinoma of the lung

A 55-year-old man, diagnosed with systemic sclerosis (SSc) for 20 years, was admitted to our hospital for exertional dyspnea and pleural effusion. Computed tomography scan and cytological findings of the pleural fluid suggested malignant mesothelioma. In the postmortem examination, the tumor was pathologically diagnosed as pseudomesotheliomatous adenocarcinoma (PMA) of the lung, classified into pleomorphic carcinoma with adenocarcinoma component according to the new World Health Organization guidelines. This is the first case report of SSc with PMA.

‘Pseudomesotheliomatous’ carcinomas of the pleura: a 10-year analysis of cases from the Environmental Lung Disease Research Group, Cardiff

AIMS

To undertake a clinicopathological study of diffuse serosal neoplasms of epithelial histogenesis which clinically and pathologically mimic malignant pleural mesothelioma.

METHODS AND RESULTS

Over a 10-year (1990-2000) study period 53 carcinomas mimicking diffuse pleural mesothelioma ('pseudomesotheliomatous' carcinoma) were identified. The study group comprised 50 men and three females, age range 33-77 (median 68) years. In 46 (87%) cases there was a history of smoking and in 40 (76%) cases a history of asbestos exposure. Histologically the pleural 'pseudomesotheliomatous' carcinomas could be divided into two broad groups: primary pulmonary carcinomas with florid pleurotropic growth (n = 47), of which 34 (70%) were adenocarcinomas; and diffuse carcinomatous involvement of the pleura by metastatic tumour (n = 6). This latter group comprised two transitional cell carcinomas of bladder, one renal (clear) cell carcinoma, one ductal pancreatic adenocarcinoma, one prostatic adenocarcinoma and one squamous cell carcinoma of parotid gland origin. Follow-up data were available in 35 cases. Regardless of tumour type, survival was poor (median 8 months) and comparable to diffuse pleural mesothelioma.

CONCLUSIONS

Pleural 'pseudomesotheliomatous' carcinomas are uncommon (comprising 6% of referrals), pathologically heterogeneous tumours with poor prognosis. Tissue diagnosis should be obtained in all cases of suspected diffuse pleural neoplasia. By light microscopy and immunophenotype many of the tumours mimicked malignant mesothelioma. In particular, an awareness that all neoplasms exhibiting squamous differentiation may express cytokeratin 5/6 and thrombomodulin is important to prevent misinterpretation. In this respect, calretinin is regarded as the most specific and sensitive mesothelial marker. Misdiagnosis may have medico-legal implications in asbestos-related compensation claims.

Pseudomesotheliomatous adenocarcinoma of the lung with rhabdoid features

Pseudomesotheliomatous adenocarcinoma of the lung is a rare entity, clinically and pathologically mimicking diffuse malignant pleural mesothelioma. We report a case of pseudomesotheliomatous adenocarcinoma consisting of two distinct histopathologic components with marked differences in morphological appearance and immunohistochemical staining pattern: a small subpleural nodule consisting of adenocarcinoma and undifferentiated carcinoma with rhabdoid features, the latter extending to the visceral pleura in a diffuse mesothelioma-like growth pattern. The adenocarcinomatous component showed strong reactivity with various epithelial markers, but no reactivity with vimentin. The undifferentiated component showed strong reactivity for vimentin, but no reactivity for epithelial markers. Both components showed no reactivity with CEA, Ber Ep4, MOC-31, B72.3, cytokeratin 5/6, calretinin and thrombomodulin. Metastatic lesions in the duodenum and the periumbilical skin consisted entirely of undifferentiated carcinoma with rhabdoid features. Fluorescence in situ hybridisation (FISH) was performed for chromosomes 4, 7, 20, and 22. FISH results showed polysomy 7 in both components. The diagnosis of pseudomesotheliomatous adenocarcinoma in this case was based on the finding of the subpleural nodule. We conclude that in cases of undifferentiated malignant pleural tumors with cells of rhabdoid phenotype, the possibility of peripheral pulmonary adenocarcinoma dedifferentiating into a more aggressive phenotype should be considered.

Pulmonary adenocarcinoma simulating malignant mesothelioma

Adenocarcinoma of the lung with pleural involvement frequently resembles pleural epithelioid mesothelioma clinically as well as macro- and microscopically. Special stains, immunohistochemical studies, and electron microscopic studies are needed to differentiate these 2 tumors. We report a case of pleural involvement by adenocarcinoma, mimicking in the hematoxylin-eosin stain an epithelioid mesothelioma, correctly identified only after immunohistochemical and electron microscopic examinations.

Glyco- and immunohistochemical refinement of the differential diagnosis between mesothelioma and metastatic carcinoma and survival analysis of patients

The aim of this study was to analyse the diagnostic value of selected glyco- and immunohistochemical probes for discrimination between mesotheliomas and metastatic carcinomas within the pleura, and to evaluate prognostic indicators in the tested panel. A panel of nine markers (five antibodies, two neoglycoproteins, and labelled hyaluronic acid) was applied to a total of 264 specimens with mesotheliomas (118 cases) and metastatic carcinomas in the pleura (146 cases); the material consisted exclusively of surgical specimens. The diagnosis obtained by standard procedures was further substantiated through a detailed follow-up and clear-cut descriptions of primary sites. The metastatic tumours originated from the lung (82 cases), breast (47 cases), colon (three cases), and kidney (two cases); in 12 cases, however, the tumour origin could not be ascertained. In detail, the probes tested included antibodies against carcinoembryonic antigen (CEA), vimentin, calretinin, mesothelial cells (HBME-1), calcyclin and keratin-5; and also biotinylated neoglycoproteins with ganglioside GM1 and N-acetyl-D-glucosamine (GlcNAc) as the ligand part, and hyaluronic acid. Carrier-immobilized ganglioside GM1 and hyaluronic acid displayed the highest specificity and sensitivity for mesotheliomas, followed by calretinin and HBME-1, whereas keratin-5 and vimentin were of low specificity (43% and 52%, respectively). Metastatic carcinomas could be discerned by CEA detection and application of GlcNAc-bearing neoglycoprotein with similar sensitivity (76% and 72%, respectively) and specificity (91% and 86%, respectively). In cases of breast carcinoma, the maximum specificity (59%) and sensitivity (67%) were low for all markers. Patients with mesothelioma survived longer than those with metastatic carcinoma, especially those with detectable binding sites for hyaluronic acid. No association of tumour type and binding properties of the other applied probes with survival of the patients could be found at a statistically significant level. It is concluded that in routine practice, the application of carrier-immobilized GM1, hyaluronic acid, and antibodies against calretinin and HBME-1 is useful for confirmation of mesothelioma, whereas the detection of CEA and GlcNAc-specific binding sites is useful for distinguishing metastatic carcinoma from mesothelioma. Despite the rather infrequent occurrence of mesotheliomas in women, particular attention should be given to exclude or confirm metastatic breast carcinoma in cases of unknown history or long metastatic interval.

Percutaneous needle biopsy of the pleura

Percutaneous needle biopsy of the pleura and thoracic wall is a relatively simple, minimally invasive, and safe technique that may be performed in an outpatient setting under local anesthesia. Image guidance, combined with the use of core biopsy needles and immunohistochemical techniques, have lead to increased diagnostic yield and overall accuracy. Open and thoracoscopic biopsies are reserved for a minority of patients in whom pleural fluid cytology and percutaneous needle biopsy are nondiagnostic.

Pseudomesotheliomatous carcinoma involving pleura and peritoneum: A clinicopathologic and immunohistochemical study of three cases

Pseudomesotheliomatous carcinoma is a rare variant of peripheral adenocarcinoma of the lung that can manifest clinical, radiologic, and pathologic features similar to malignant mesothelioma. We present three patients with pseudomesotheliomatous carcinoma of the lung. In one patient the carcinoma extended beyond the thorax and extensively involved the peritoneum, mesentery, omentum, and intestines. All patients experienced weight loss and chest pain. All were white men aged 63, 65, and 67 years. Two were smokers and had shortness of breath, cough, and pleural effusion. One had a history of asbestos exposure. No patient developed dyspnea or hemoptysis. One was successfully treated for prostatic carcinoma 18 months earlier. Radiographically, all tumors were pleura-based. Grossly, the tumors spread extensively over pleural (and in one case peritoneal) surfaces and mimicked malignant mesothelioma. Histologically, all tumors were poorly differentiated and necrotic; two tumors exhibited spindle-cell components and desmoplasia. Mucin production was detectable in none, 10%, and 50% of tumor cells. The percentages of tumor cells immunoreactive for Ber-EP4 were 70%, 100%, and 80%; for Leu MI 0%, 90%, and 50%; for epithelial membrane antigen 80%, 80%, and 100%; for B 72.3%, 0%, 90%, and 20%; for polyclonal carcinoembryonic antigen 0%, 10%, and 10%; and for monoclonal 5%, 0%, and 0%. Of these, Ber-EP4 and B 72.3 rendered the most reliable diagnostic results. The clinical, radiologic, and gross and routine histologic findings were similar to those of a malignant mesothelioma; the final diagnosis could be made based mainly on immunocytochemical results. We have reviewed the English and German literature regarding 65 such tumors and present our experience with three additional cases. We emphasize the application of immunocytochemical studies on pleura-based poorly or undifferentiated malignant tumors of unknown origin.