mesothelioma
26 Jan 2009 | Tagged as: Uncategorized
There is general agreement that the microscopic characteristics of an adenocarcinoma involving the pleura and an epithelioid mesothelioma overlap in the hematoxylin-eosin-stained slide. Additional studies such as electron microscopy and immunohistochemical stains are needed for proper identification.1 We describe a pleural tumor with “typical” features of mesothelioma in the hematoxylin-eosin stain slide that with further studies was reclassified as adenocarcinoma. A 75-year-old male retired biology teacher with a history of hypertension, transient ischemic attack, and depression and a remote history of smoking presented with dry cough, respiratory distress, and weight loss of several months duration. A chest radiograph showed left side pleural effusion. The patient underwent thoracentesis. Cytology of the pleural fluid was positive for malignant cells, with a differential diagnosis of epithelioid mesothelioma versus adenocarcinoma. Subsequently, the patient underwent partial pleurectomy. The pleurectomy specimen was characterized by fragments of fibrous connective tissue lined by mesothelial cells with focal papillary area. Normal mesothelium was found in continuity with hyperplastic stratified and papillary structure without invasion of the underlying fibrous connective tissue. The cells were cuboidal in the hyperplastic and papillary areas, with an increased nucleocytoplasmic ratio, round bland nuclei with low mitotic activity, and inconspicuous nucleoli (Figure 1). Thus, a diagnosis of malignant mesothelioma, epithelioid type was rendered. However, additional clinical inflammation challenged the diagnosis of epithelioid mesothelioma. The patient had a 4.4-cm perihilar mass; furthermore, the patient also had a probable brain mass (2 small enhancing lesions evaluated by magnetic resonance imaging), bony metastasis (multiple areas of increasing uptake evaluated by bone scan) and a 3-cm lesion in the right kidney (based on computed tomographic scan). All this additional clinical information favored a diagnosis of adenocarcinoma rather than malignant mesothelioma. Subsequent studies of this tumor showed that it stained positive for Leu Ml, CK7, D-PAS, and alcian blue (hyaluronidase resistant) and negative for calretinin, carcinoembryonic antigen, and CK20 (Figure 2). Electron microscopic study showed tumor cells with short, widely spaced microvilli and some cells forming ductlike lumen and apical junction complex (Figure 3). All of these studies supported a diagnosis of adenocarcinoma.
LA JOLLA, Calif. — All About Malignant Mesothelioma, an online resource for information about mesothelioma causes, symptoms and treatments, has recently published a revised section on mesothelioma drug treatments. Mesothelioma is a rare, aggressive form of cancer. Its long dormancy period after exposure to asbestos and its rarity usually mean a late-stage diagnosis. Treatment options have been limited, and the prognosis for victims is poor, with typical survival times of less than two years after diagnosis. In the last several years, however, considerable research has focused on new treatments for this disease. Alimta (pemetrexed), manufactured and distributed by Eli Lilly and Company, when used in conjunction with Cisplatin, is approved for the treatment of patients with malignant pleural mesothelioma when surgery is not an option. Other new treatment research has focused on anti-angiogenesis, or impeding the rapid blood vessel growth that erupts during mesothelioma cancer and supplies the tumor cells. Veglin (VEGF-AS), produced by VasGene Therapeutics, Inc., is an anti-angiogenesis drug still in clinical trials, and Onconase (ranpirnase), developed and manufactured by Alfacell Corporation, is one such drug that has shown promise in the first two phases of clinical trials.
A possible cancer-causing link has been found between asbestos fibers and a monkey virus, SV40, that infects people in the U.S., as reported in a study in the Aug. 31 issue of the Proceedings of the National Academy of Sciences. The research, conducted by Michele Carbone at the Cardinal Bernardin Cancer Center of Loyola University Medical Center (Maywood, IL), offers preliminary evidence that the virus, Simian virus 40 (SV40), and asbestos fibers work together to transform healthy cells into malignant ones, resulting in mesothelioma, a rare and fatal form of cancer. Infection with SV40 apparently became widespread during the late 1950s and early 1960s when the U.S. population was inoculated with polio vaccine made from monkey cell cultures contaminated by the virus. The contaminated vaccine was no longer used after 1963. Even so, the virus can be found today in both adults and children. The exact means by which the virus is transmitted from person to person is unknown, although the virus is apparently present in blood and other bodily fluids, including breast milk. Normally, SV40 kills most human cells it enters because it keeps making copies of itself inside the cell until the cell dies. Because the infected cell dies, no cancer can occur.