Diagnosis of Mesothelioma
Diagnosis of mesothelioma is often delayed because early symptoms resemble pneumonia, lung cancer, or irritable bowel syndrome.
The disease can remain silent for decades after asbestos exposure, making it hard for patients and doctors to connect current symptoms to past risks. Doctors need high suspicion, especially for patients with known asbestos exposure. Early and accurate diagnosis is critical for guiding treatment and improving outcomes. A team approach using imaging, pathology, and biomarker studies is essential. Mesothelioma should be diagnosed by experienced oncologists and pathologists.
1. Initial Clinical Evaluation
The diagnostic process begins with a complete medical history. Doctors ask about asbestos exposure, family history of cancer, past respiratory or digestive conditions, and lifestyle factors like smoking. Next, a full physical exam looks for signs such as fluid in the chest or abdomen or lumps in the testicular area.
2. Imaging Studies
Imaging helps detect tumour size, location, and possible spread.
Chest X-ray
This is usually the first test, especially for suspected pleural mesothelioma. It can show pleural thickening, fluid buildup, lung collapse, or tumour masses. An X-ray alone does not confirm diagnosis.
Computed Tomography (CT) Scan
CT scans provide detailed cross-sectional images of the chest or abdomen. They help detect tumour spread, lymph node involvement, and invasion of nearby structures. CT scans also guide biopsies.
Magnetic Resonance Imaging (MRI)
MRI gives better soft tissue contrast. It is used to check diaphragm, chest wall, nerve, or spinal cord involvement and helps plan surgery in resectable cases.
Positron Emission Tomography (PET) Scan
PET scans show metabolic activity. Cancer cells use more glucose and appear bright on imaging. PET scans confirm cancer spread, detect distant metastases, and assess treatment response. PET-CT combines both techniques for thorough evaluation.
3. Biopsy Procedures
A confirmed diagnosis requires tissue examination under a microscope. The biopsy method depends on tumour location.
Thoracoscopy is used for pleural mesothelioma. A small chest incision allows tissue sampling. Laparoscopy is used for peritoneal mesothelioma and collects abdominal tissue samples. Mediastinoscopy biopsies mediastinal lymph nodes. Needle biopsy, guided by CT or ultrasound, collects smaller samples but is less invasive.
4. Histopathology and Subtype Classification
Pathologists examine tissue to determine if cancer is present and identify the subtype. Epithelioid mesothelioma has the best prognosis. Sarcomatoid mesothelioma is aggressive. Biphasic mesothelioma is a mix of both. Subtype guides treatment and prognosis.
5. Immunohistochemistry
Because mesothelioma resembles other cancers, additional staining tests help confirm diagnosis. Common markers include calretinin, WT-1, cytokeratin 5/6, D2-40, and mesothelin. Absence of other markers helps rule out lung or gastrointestinal cancer.
6. Fluid Cytology
When fluid collects in the chest or abdomen, it may be examined for cancer cells. Fluid cytology alone rarely gives a conclusive diagnosis, as malignant cells can look similar to reactive cells.
7. Biomarkers in Blood
Research is exploring blood biomarkers like soluble mesothelin-related peptides, fibulin-3, and osteopontin. These may help early detection or monitoring but are not yet reliable for standalone diagnosis.
8. Challenges in Diagnosis
Diagnosing mesothelioma is difficult because symptoms can take 20–50 years to appear, resemble benign conditions, overlap with other cancers, or result in small or poor-quality biopsy samples. Centres with mesothelioma expertise are essential.
9. Second Opinions and Specialist Centres
Patients should seek second opinions from specialist centres. These centres have advanced imaging, experienced pathologists, multidisciplinary boards, and access to clinical trials. This can speed up diagnosis and improve treatment plans.
Final Thoughts
The diagnosis of mesothelioma involves careful history, imaging, biopsy, and tissue analysis. It requires a team of specialists to ensure accuracy. Early and precise diagnosis expands treatment options, including surgery, chemotherapy, immunotherapy, and clinical trials. Awareness among healthcare providers and high-risk populations is vital.
