A disease of poor prognosis: Malignant Mesothelioma.

In the chest X-ray, a right external posterior basal opacity was observed on the lateral radiograph, without a clear semiology, which was associated with a certain pleural effusion / thickening.

The patient was asked to perform a CT scan in which a “right thoracic wall mass was observed between the 5th to 8th right ribs with intra- and extrathoracic components, pleural implants and associated pleural effusion”. Differential diagnosis between primary sarcoma (primitive neuroectodermal tumor, malignant fibrous histiocytoma, fibrosarcoma, rhabdomyosarcoma), mesothelioma, lymphoma and metastasis.

Before the findings, entered the service of Internal Medicine for the study of mass. MRI – which considered the same possibilities described in chest X-ray, thoracentesis and biopsy were also inconclusive, so the patient was transferred to the Thoracic Surgery Service to perform an open thoracotomy to obtain a sample of the lesion And to proceed to its anatomopathological study.

The results of the biopsy confirmed the presence of pleural tissue massively infiltrated by neoplastic proliferation of epithelioid habit with multinucleated cells with atypical vesicular chromatin nuclei showing immunohistochemical techniques showing positive mesothelial cell markers: low weight CK, CK7, CK5 -6, thrombomodulin and calretinin. All of this was suggestive of a compensation mesothelioma of a well differentiated epithelial type with extension to the chest wall. Given the thoracic extension of the tumor, surgical intervention was rejected as a curative method and the patient is currently receiving chemotherapy for palliative purposes.

Malignant mesothelioma is a rare tumor, occurring between the fifth and seventh decades of life, and clearly related to the prolonged exposure to asbestos (approximately after 30-40 years of exposure), both occupational (appears around 10% in workers In contact with asbestos) as environmental. In the coming years it is anticipated that there will be a decrease in its incidence in developed countries due to the law regulating environmental exposure to asbestos but, on the contrary, an increase in third world countries due to increased industrialization and absence Of regulation of its use.

However, there are other aetiological factors such as radiotherapy, viral oncogenes (SV-40), inhalation of carbon fibers, silica and thorium dioxide-Thorotrast-. Sulfur is classified as carcinogenic but, at present, there is no causal relationship between its environmental exposure and mesothelioma.

Malignant mesothelioma is classified into 3 histological subtypes: the epithelial, sarcomatous, and mixed. The epithelial is the most common variant – representing approximately 50-60% of mesotheliomas – and the one with the best prognosis. The sarcomatose consists of cells that can mimic malignant mesenchymal tumors such as fibrosarcoma or leiomyosarcoma. In the mixed cells of the two previous coexist.

At present, immunohistochemical techniques allow differentiation of epithelioid mesothelioma from other lung tumors; Above all allows differentiation of metastatic adenocarcinoma. The immunohistochemical markers that aid the diagnosis of mesothelioma are the cytokeratine -CK, CK5-6, CK7-, calretinin, WT1, mesothelin and thrombomodulin.

The most frequent presenting symptoms are dyspepsia and non-pleuritic chest pain. It is less common to present as a pleural effusion detected as a casual finding when performing a chest X-ray – most patients have unilateral pleural thickening and only 20% show radiological signs of asbestosis.

Sometimes it will be part of a paraneoplastic syndrome: disseminated intravascular coagulation, thrombophlebitis, thrombocytosis, hemolytic anemia, hypoglycemia and hypercalcemia. Specificity of symptoms, delayed completion of complementary examinations, and sometimes absence of asbestos exposure, delay diagnosis.

The confirmation diagnosis will be histologist, but in most cases, the tissue obtained by thoracentesis or closed pleural biopsy is not possible and a thoracoscopy or open thoracotomy should be performed to obtain a tissue sample for anatomopathological analysis. Between 60 and 75% of the cases require a thoracoscopy to obtain a tissue sample representative of the tumor and approximately 88% of the cases require an open thoracotomy.

Differential diagnosis includes both benign and malignant processes; For example inflammatory reactions such as empyema, Pleural Mesothelioma Stages of primitive tumors-lung, stomach, kidney, ovary, thymus and prostate-malignant histiocytoma and fibrosarcoma.

The clinical course depends on the local invasion of the tumor and may cause, in advanced cases, complications such as dysphagia, spinal cord compression, brachial plexus involvement, Horner syndrome, superior vena cava syndrome, etc. Although rare, pulmonary, peritoneal, and cerebral metastases may also appear. The mean survival of patients with mesothelioma is 6 to 18 months regardless of the therapeutic intervention practiced.

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