In a 70 years old man, who was working in asbestos factory for 10-15 years, a mass was seen in right apical region of the lung on a routine X-ray,. Biopsy was taken from the mass. Which of the following is seen on electron microscopic examination?

Most likely diagnosis on the basis of description is malignant mesothelioma. Numerous long, slender microvilli will be seen on electron microscopy in malignant mesothelioma.Diagnosis depends on a constellation of findings, including history of asbestos exposure, clinical signs and symptoms, radiographic findings, histopathological features, and immunohistochemical and ultrastructural studies.On electron microscopy, the presence of long microvilli and abundant tonofilaments but absent microvillous rootlets and lamella bodies ors the diagnosis of malignant mesothelioma.Mesothelioma cells are characterized by a profusion of markedly elongated surface microvilli in the absence of secretory cytoplasmic granules. - Robbin's 8/e