General Guide on Mesothelioma Meaning, pathology, Radiology
Published: 07/08/2023, 9.12 PM IST
Mesothelioma Meaning
Mesothelioma Pathology Outlines
Mesothelioma Radiology
Mesothelioma Meaning
Mesothelioma is a rare and aggressive form of cancer that develops in the thin layer of tissue, known as the mesothelium, which covers the internal organs. It most commonly affects the lining of the lungs (pleura), but it can also occur in the abdomen (peritoneum), heart (pericardium), and other organs where mesothelial cells are present.
About 3,000 people are diagnosed with mesothelioma each year in the United States. Worldwide, an estimated 30,870 people were diagnosed with mesothelioma in 2020.
More read - Mesothelioma in detail, Mesothelioma Survival Rate
Mesothelioma Pathology Outlines
Histology of mesothelioma
Histological classification of mesothelioma is shown in Figs. There are three major types epithelioid type, sarcomatoid type and biphasic type and the proportion of each is approximately 60, 20 and 20%, respectively (Figs. (Figs.1, ,2, ,3) . The desmoplastic type is rare (probably 1–2%) (Fig. (Fig.4),4), and special variants only appear sporadically (several percentages). However, the proportion of each histological type varies among the reports because of the large variety of histological analyses used .
Understanding Mesothelioma Subtypes:
Mesothelioma exhibits three primary histological subtypes: epithelioid, sarcomatoid, and biphasic. Epithelioid mesothelioma, comprising 50-70% of cases, is characterized by cuboidal cells forming gland-like structures, often mistaken for adenocarcinoma. Sarcomatoid mesothelioma features elongated, spindle-shaped cells resembling sarcoma, while biphasic mesothelioma is a combination of both subtypes.
Diagnostic Techniques and Immunohistochemistry:
Accurate diagnosis of mesothelioma requires a comprehensive assessment of histopathological characteristics, often aided by immunohistochemistry. The differential expression of markers like calretinin, WT1, CK5/6, and D2-40 helps distinguish mesothelioma from other malignancies. These techniques contribute to a precise classification of mesothelioma subtypes, aiding in treatment planning.
Role of Asbestos Exposure:
Asbestos exposure remains the foremost risk factor for developing mesothelioma. Inhalation of asbestos fibers triggers chronic inflammation, DNA damage, and genetic alterations within mesothelial cells. Long latency periods, often spanning decades, further complicate diagnosis and management. The intricate interplay between asbestos and genetic factors in mesothelioma pathogenesis underscores the need for targeted research.
Molecular Mechanisms and Therapeutic Implications:
Emerging research reveals the involvement of various molecular pathways in mesothelioma progression. Dysregulated signaling pathways, such as PI3K/AKT/mTOR and MAPK, contribute to cell proliferation, survival, and metastasis. Novel therapies targeting these pathways, including tyrosine kinase inhibitors and immune checkpoint inhibitors, offer promising avenues for treatment.
Mesothelioma Radiology
Imaging Modalities in Mesothelioma Diagnosis:
Radiology offers a range of imaging modalities to aid in the diagnosis and management of mesothelioma. Chest X-rays provide an initial overview, while computed tomography (CT) scans offer detailed cross-sectional images, revealing the extent of disease spread and potential metastasis. Positron emission tomography (PET) scans, combined with CT (PET/CT), provide functional information by highlighting areas of increased metabolic activity, aiding in disease staging and treatment planning.
Characteristic Radiological Findings:
Mesothelioma presents with distinctive radiological features that guide its diagnosis. Pleural effusion, often the initial manifestation, is identified through X-rays and CT scans. Thickened pleura, nodular pleural thickening, and pleural masses are common findings, showcasing the malignancy's local invasion. The "rind-like" or "circumferential" pleural thickening pattern is particularly indicative of mesothelioma. In advanced stages, chest wall invasion, diaphragmatic involvement, and mediastinal lymph node enlargement become apparent.
Advancements in Imaging Technology:
The field of mesothelioma radiology has witnessed rapid technological advancements. Magnetic resonance imaging (MRI) enhances soft tissue visualization, aiding in differentiating mesothelioma from benign conditions. Diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI provide valuable insights into tumor cellularity and vascularity. Cutting-edge techniques like virtual bronchoscopy and 3D reconstruction enhance surgical planning by providing intricate anatomical details.
