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

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.

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.

Local recurrence of lung adenocarcinoma 10 years after left upper lobectomy resembling pseudomesotheliomatous adenocarcinoma: a case report

The form and timing of the local recurrence of lung cancer can be unpredictable and unexpected. Pseudomesotheliomatous adenocarcinoma is a rare tumor that mimics malignant pleural mesothelioma both clinically and pathologically. Distinguishing pseudomesotheliomatous adenocarcinoma from malignant pleural mesothelioma on the basis of clinical findings can be difficult; therefore, a biopsy is usually required for diagnosis. Here we report on a 73-year-old Japanese man who presented with extensive dissemination along the pleural surfaces and clinical findings similar to those of pseudomesotheliomatous lung cancer 10 years after undergoing left upper lobectomy for lung adenocarcinoma. This report provides information that will help physicians establish an accurate diagnosis in similar cases.

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.

[Pseudo-mesotheliomatous adenocarcinoma of the lung]

Both pathologists and clinicians are challenged by the diagnosis of a particular variant of the peripheral adenocarcinoma with involvement of the pleura parietalis, the so-called pseudo-mesotheliomatous adenocarcinoma of the lung (PMAC), which is hard to differentiate from epithelioid mesothelioma on imaging and cytology, macroscopically as well as histologically. However, the exact diagnosis is not only crucial for the patient's therapy but also for insurance matters. Immunohistochemical evaluation represents a quick and a relatively cheap tool for which a few antibody panels have been proposed in recent years as being suitable to distinguish between these two entities. One of the positive markers for epithelioid mesothelioma most often suggested seems to be calretinin. We would like to report on a case of PMAC with the special feature of positive calretinin immunohistochemical staining. Using histochemistry and a few additional antibodies we were able to reliably characterize the tumor and provide the patient with appropriate therapy. This article gives a short overview of the possibilities available for distinguishing between these two entities in the context of a case report.

Pseudomesotheliomatous carcinoma of the lung with a distinct morphology, immunohistochemistry, and comparative genomic hybridization profile

We report 4 cases of pseudomesotheliomatous carcinoma of the lung, which has clinical and microscopic features similar to malignant mesothelioma, but with ultrastructural, immunohistochemical, and molecular characteristics suggestive of a histogenesis from type II pneumocytes. Neoplasm grows as a diffuse or solid pattern of large polygonal cells with sharply defined borders. Hale's colloidal iron is positive in the cytoplasm of small groups of cells and, focally, in some intercellular spaces. Ultrastructure showed short microvilli in the surface. Immunohistochemically, tumor cells were positive for thyroid transcription factor-1, podoplanin, mesothelin, pan-cytokeratin, CK-7, CK-19, Ber-EP4, epithelial membrane antigen, apoprotein surfactant A, epidermal growth factor receptor, Leu-M1, carcinoembryonic antigen, E-cadherin, and CD-44 and negative for mesothelioma markers thrombomodulin and calretinin. In some areas, there were small cysts which contained a concentric fibrilar basophilic material apoprotein surfactant A positive. Chromosomal imbalances with comparative genomic hybridization technique were identified with a median of 15 abnormalities per case (range, 1-26): 51 gains, 6 losses, and 1 high-level amplification. The most frequent aberrations among the cases were gains on chromosomes regions 1q, 3q, 5p, 8q, 16p, and 18q and losses in 17p11-13 and 17q 22-q25. High-level amplifications were detected on 7p13-p21. In all cases, there was a characteristic association between the gains on 16p and those on 18q. The 4 cases resulted in death in less than 14 months, in spite of complete surgery and chemotherapy in 2 cases. Our aim is to complement the current understanding of this pseudomesotheliomatous "pneumocytic" carcinoma and alert pathologists to this rare entity to avoid misdiagnosis.

Diffuse intra-abdominal clear cell myomelanocytic tumor: report of an unusual presentation of "PEComatosis" simulating peritoneal mesothelioma

We report a case of diffuse myomelanocytic tumor of the peritoneum that simulates, clinically and instrumentally, a malignant mesothelioma. The patient was a 70-year-old woman with a history of ancient hysterectomy for fibroids, who presented with abdominal discomfort. Exploratory laparotomy revealed diffuse encasing of the peritonealized organs by a thin, fleshy, gray-white tissue rind. Scattered tumor masses were present as well. A dominant lesion measuring 6 cm in larger size was resected from the pelvis. Histological examination revealed a tumor composed of epithelioid and spindle cells, exhibiting either a clear or slightly eosinophilic cytoplasm and a mild to moderate nuclear pleomorphism. Focal areas of necrosis could be documented. Immunohistochemically, tumor cells were positive for HMB45, melan-A, and smooth muscle actin, but negative for other antibodies, including epithelial markers, desmin, and S100 protein. We believe that this case represents an example of myomelanocytic tumor of uncertain biologic potential, a member of the recently devised perivascular epithelioid cell tumors (PEComa), with an unusual presentation simulating a diffuse mesothelial neoplasm. The origin of this particular lesion is briefly discussed in light of the recent literature published on the subject.

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.

High-Grade Neuroendocrine Carcinoma of the Lung Presenting an Unusual Spread Mimicking Pleural Mesothelioma Associated with Dermatomyositis

Neuroendocrine tumors of the lung comprise a heterogeneous group of tumors that represents a spectrum of disease from typical carcinoid tumors to the high-grade neuroendocrine carcinomas (large-cell neuroendocrine carcinomas and small-cell carcinomas). The high-grade neuroendocrine carcinomas are characterized by early metastasis and poor prognosis. The peripheral location and especially the massive pleural spread are rare for a high-grade neuroendocrine carcinoma. We report a case in which a high-grade neuroendocrine carcinoma, associated with dermatomyositis, presented an unusual pattern of progression, mimicking malignant pleural mesothelioma on diagnostic imaging.

‘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.