On biopsy, characteristic finding of malignant mesothelioma is -
Ref:Textbook of pathology (Harsh mohan)6th edition, page no.506 Malignant (Diffuse) Mesothelioma Malignant or diffuse mesothelioma is rare. It is a highly malignant tumour associated with high moality. The tumour is significant in view of its recognised association with occupational exposure to asbestos (paicularly crocidolite) for a number of years, usually 20 to 40 years . About 90% of malignant mesotheliomas are asbestos-related. Mechanism of carcinogenicity by asbestos is not quite clear but it appears that prolonged exposure of amphibole type of asbestos is capable of inducing oncogenic mutation in the mesothelium. However, prolonged asbestos-exposure is considered more significant rather than heavy exposure as documented by occurrence of malignant mesothelioma in the family members of asbestos workers. Although combination of cigarette smoking and asbestos exposure greatly increases risk to develop bronchogenic carcinoma, there is no such extra increased risk of developing mesothelioma in asbestos workers who smoke. Recently, SV40 (simian vacuolating virus) antigen has also been implicated in the etiology of mesothelioma. Grossly, the tumour is characteristically diffuse, forming a thick, white, fleshy coating over the parietal and visceral Grossly Microscopically, malignant mesothelioma may have epithelial, sarcomatoid or biphasic patterns. SECTION III Systemic Pathology Malignant (diffuse) mesothelioma, gross appearance. The tumour is seen to form a thick, white, fleshy coat over the parietal and visceral surfaces. osteoahropathy or hypoglycaemia. Removal of the tumour is generally curative. Malignant (Diffuse) Mesothelioma Malignant or diffuse mesothelioma is rare. It is a highly malignant tumour associated with high moality. The tumour is significant in view of its recognised association with occupational exposure to asbestos (paicularly crocidolite) for a number of years, usually 20 to 40 years (page 492). About 90% of malignant mesotheliomas are asbestos-related. Mechanism of carcinogenicity by asbestos is not quite clear but it appears that prolonged exposure of amphibole type of asbestos is capable of inducing oncogenic mutation in the mesothelium. However, prolonged asbestos-exposure is considered more significant rather than heavy exposure as documented by occurrence of malignant mesothelioma in the family members of asbestos workers. Although combination of cigarette smoking and asbestos exposure greatly increases risk to develop bronchogenic carcinoma, there is no such extra increased risk of developing mesothelioma in asbestos workers who smoke. Recently, SV40 (simian vacuolating virus) antigen has also been implicated in the etiology of mesothelioma. Grossly, the tumour is characteristically diffuse, forming a thick, white, fleshy coating over the parietal and visceral surfaces . i)Epithelial pattern resembles an adenocarcinoma, consisting of tubular and tubulo-papillary formations. The tumour cells are usually well-differentiated, cuboidal, flattened or columnar cells. ii)Sarcomatoid pattern consists of spindle cell sarcoma resembling fibrosarcoma. The tumour cells are arranged in a storiform pattern with abundant collagen between them. iii)Biphasic pattern shows mixed growth having epithelial as well as sarcomatoid pattern. Usually, there are slit-like or gland-like spaces lined by neoplastic mesothelial cells separated by proliferating spindleshaped tumour cells . Asbestos bodies are found in the lungs of most patients with malignant mesothelioma of any histologic type On biopsy, mesothelioma is seen as branching microvilli like appearance.
Myelin
Desmosin
Weibel-palade bodies
Branching microvilli
Respiratory system