Diagnosis

Most cancers are initially recognized either because signs or symptoms appear or through cancer screening. Neither of these lead to a definitive diagnosis, which usually requires the opinion of a pathologist, a type of physician (medical doctor) who specializes in the diagnosis of cancer and other diseases. People with suspected cancer are investigated with medical tests. These commonly include blood tests, X-rays,CT scans and endoscopy.

Pathology

A cancer may be suspected for a variety of reasons, but the definitive diagnosis of most malignancies must be confirmed by histologicalexamination of the cancerous cells by a pathologist. Tissue can be obtained from a biopsy or surgery. Many biopsies (such as those of the skin, breast or liver) can be done in a doctor's office. Biopsies of other organs are performed under anesthesia and require surgery in anoperating room.

The tissue diagnosis given by the pathologist indicates the type of cell that is proliferating, its histological grade, genetic abnormalities, and other features of the tumor. Together, this information is useful to evaluate the prognosis of the patient and to choose the best treatment.Cytogenetics and immunohistochemistry are other types of testing that the pathologist may perform on the tissue specimen. These tests may provide information about the molecular changes (such as mutations, fusion genes, and numerical chromosome changes) that has happened in the cancer cells, and may thus also indicate the future behavior of the cancer (prognosis) and best treatment.

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  An invasive ductal carcinoma of the breast (pale area at the center) surrounded by spikes of whitish scar tissue in the surrounding yellow fatty tissue.

 

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  An invasive colorectal carcinoma (top center) in acolectomy specimen.

 

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  A squamous cell carcinoma (the whitish tumor) near the bronchi in a lung specimen.

 

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  A large invasive ductal carcinoma in amastectomy specimen.

Serous carcinoma

In pathology, serous carcinoma is an epithelial malignancy (carcinoma) that arises from the lining of a cavity that produces a serum-like fluid (a serous cavity).

Serous lined cavities include the peritoneum, pericardium and pleural space and tunica vaginalis.

Cytologic features

• Marked intragroup nuclear pleomorphism.



• Macronucleoli.


• "Knobby" group borders (in large groups).


• Hydropic vacuoles.

[]Differential diagnosis

The differential diagnosis of serous carcinoma not otherwise specified includes:

• Ovarian serous carcinoma, a type of ovarian cancer.



• Uterine serous carcinoma, also known as uterine papillary serous carcinoma, a type of uterine cancer.


• Fallopian tube serous carcinoma, a type of uterine tube cancer.


• Cervical serous carcinoma, a rare type of cervical cancer.


• Primary peritoneal serous carcinoma, a very rare cancer that arise from the peritoneum.

There has been the suggestion that the above diagnoses really represent one entity

Diagnosis

Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history. A history of exposure to asbestos may increase clinical suspicion for mesothelioma. A physical examination is performed, followed by chest X-ray and often lung function tests. The X-ray may reveal pleural thickening commonly seen after asbestos exposure and increases suspicion of mesothelioma. A CT (or CAT) scan or an MRI is usually performed. If a large amount of fluid is present, abnormal cells may be detected by cytopathology if this fluid is aspirated with a syringe. For pleural fluid, this is done bythoracentesis or tube thoracostomy (chest tube); for ascites, with paracentesis or ascitic drain; and for pericardial^{[disambiguation needed]} effusion with pericardiocentesis. While absence of malignant cells on cytology does not completely exclude mesothelioma, it makes it much more unlikely, especially if an alternative diagnosis can be made (e.g. tuberculosis, heart failure). Unfortunately, the diagnosis of malignant mesothelioma by cytology alone is difficult, even with expert pathologists.

Generally, a biopsy is needed to confirm a diagnosis of malignant mesothelioma. A doctor removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside the chest and obtain tissue samples. Alternatively, the chest surgeon might directly open the chest (thoracotomy). If the cancer is in the abdomen, the doctor may perform a laparoscopy. To obtain tissue for examination, the doctor makes a small incision in the abdomen and inserts a special instrument into the abdominal cavity. If these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.

Immunohistochemical studies play an important role for the pathologist in differentiating malignant mesothelioma from neoplastic mimics. There are numerous tests and panels available. No single test is perfect for distinguishing mesothelioma from carcinoma or even benign versus malignant.

Typical immunohistochemistry results

Positive	Negative
EMA (epithelial membrane antigen) in a membranous distribution	CEA (carcinoembryonic antigen)
WT1 (Wilms' tumour 1)	B72.3
Calretinin	MOC-3 1
Mesothelin-1	CD15
Cytokeratin 5/6	Ber-EP4
HBME-1 (human mesothelial cell 1)	TTF-1 (thyroid transcription factor-1)

There are three histological types of malignant mesothelioma: (1) Epithelioid; (2) Sarcomatoid; and (3) Biphasic (Mixed). Epithelioid comprises about 50-60% of malignant mesothelioma cases and generally holds a better prognosis than the Sarcomatoid or Biphasic subtypes.^[22]

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Staging

Staging of mesothelioma is based on the recommendation by the International Mesothelioma Interest Group.^[23] TNM classification of the primary tumor, lymph node involvement, and distant metastasis is performed. Mesothelioma is staged Ia–IV (one-A to four) based on the TNM status.