Cytopathology is commonly used to study a wide range of body sites, often to aid in the diagnosis of cancer, but also in the diagnosis of certain infectious diseases and other inflammatory conditions. For example, a common application of cytopathology is Pap smear, a screening tool used to detect precancerous cervical lesions that can lead to cervical cancer. Cytopathological tests are sometimes called smear tests because they can be spread on a glass microscope slide for later staining and microscopic examination. However, cytology samples can be prepared by other means, including cytocentrifugation. Different types of smear tests can also be used to diagnose cancer. In this sense, it is called a cytological smear.
Cytopathology is best used as one of three tools, the second and third being the physical examination and medical imaging. Cytology can be used to diagnose a condition and spare a patient from surgery to obtain a larger specimen. An example is thyroid FNAC; many benign conditions can be diagnosed with a superficial biopsy and the patient can go back to normal activities right away. If a malignant condition is diagnosed, the patient may be able to start radiation/chemotherapy, or may need to have surgery to remove and/or stage the cancer. Some tumors may be difficult to biopsy, such as sarcomas. Other rare tumors may be dangerous to biopsy, such as pheochromocytoma. In general, a fine-needle aspiration can be done anywhere it is safe to put a needle, including liver, lung, kidney, and superficial masses.