Pathological Approach to Pleural Malignant Mesothelioma

Exposure to asbestos can lead to asbestosis or malignancy 10-40 years after initial exposure [1]. Although its use has been banned in multiple countries, past occupational exposure leads to most cases that we see in present time. Malignant mesothelioma is an insidious and rare neoplasm that can arise from mesothelial surface cells, being Malignant Pleural Mesothelioma (MPM) the most common type. Lifetime risk of developing mesothelioma among asbestos workers can be as high as 10 percent and latency period is approximately 30-40 years since time of exposure to development of disease [2]. Annual incidence in the united states is approximately 3,300 cases per year [3]. Median overall survival of patients with advanced unresectable disease is approximately 12 months [4]. Clinical suspicion should arise in patients with previous exposure to asbestos who present with pleural thickening and/or effusion with associated respiratory symptoms. Most symptoms are nonspecific such as chest pain, dyspnea, cough and night sweats. Initial evaluation includes chest x-ray, contrast enhanced CT of the chest to find pleural abnormalities, thoracentesis and closed pleural biopsy. However, difficulties establishing diagnosis have been illustrated on studies where thoracentesis and pleural fluid cytology only yields diagnosis in 26% of cases. The diagnosis, then, is established by morphologic and immunohistochemistry findings of cytologic and surgical specimens.

War journalism: an occupational exposure

Apart from the risk of accidents, war theatres present a hazard related to numerous long-lasting toxic agents. For 10 years, a >60-year-old male journalist worked in war theatres in the Far and Near East where he was exposed to asbestos and other toxic substances (metals, silica, clays, polycyclic aromatic hydrocarbons and other organic substances) contained in dust and smoke of destroyed buildings. More than 15 years later, he developed a mucoepidermoid carcinoma of the soft palate and, subsequently, a pleural malignant mesothelioma. The safety of war journalists should focus not only on preventing the risk of being killed, but also on providing protection from toxic and carcinogenic agents. Exposure to substances released during the destruction of buildings can also pose a carcinogenic risk for survivors.

Pleural malignant mesothelioma with metastatic deposition in the tongue

A 70-year-old man with epithelioid malignant pleural mesothelioma was referred to the maxillofacial surgery department with a painful lesion on the lateral border of his tongue which interfered with swallowing. Physical examination demonstrated a 3 cm firm, non-ulcerated mass on the left lateral tongue, histologically shown to be metastatic epithelioid mesothelioma. MRI of the neck and CT scan of the thorax, abdomen and pelvis scans also demonstrated progressive local and metastatic disease. The patient was not felt to be fit for further treatment. More than 90% of oral cavity cancers are squamous cell carcinoma. All reported cases of metastasis of malignant mesothelioma to the tongue have been of the epithelioid subtype with 10 cases reported in the literature to date. Diagnosis is important as tongue lesions can significantly impact on quality of life and synchronous tongue primaries should be ruled out. Tongue lesions may herald metastases to other extrapleural locations.