Specimens are submitted to the histopathology laboratory for the diagnosis of malignancy or evaluation of other diseases such as inflammatory disorders (including autoimmune and infectious) and metabolic disease.

Histopathology studies the effect of disease on the structure or morphology of body organs and tissues, both macro- and microscopically.

Cytopathology is the branch of histopathology which involves disease diagnosis, most often of precancerous or cancerous lesions, by means of microscopic analysis of cellular material (as opposed to intact tissue, as for histopathology).

HISTOPATHOLOGY:

The patient is often required to undergo surgery to get a sufficient sample in the form of a biopsy or excisional/resection specimen. This is then submitted to the laboratory in a fixative solution (usually formalin) and processed for examination.

The most common specimens received include skin, gastrointestinal, endometrial, kidney and liver biopsies, as well as an excised organ such as an appendix, gallbladder or lymph node, and a resection specimen (often in the management of a tumour), such a breast lumpectomy/mastectomy, nephrectomy and colectomy.

CYTOPATHOLOGY:

The most common specimen analysed is cervical cytology, which is procured by scraping off cellular material from the cervix using a brush or spatula.

This specimen may be received in a fixative solution (so-called liquid-based cytology (LBC)) or as an already prepared and fixed smear (so-called Pap smear).

Other cytopathology specimens include various body fluids (e.g. those abnormally extruded into the abdominal or pleural cavity) and fine needle aspirations (FNA).

FNA refers to a procedure whereby cellular material is procured from any suspicious or abnormal lesions (usually nodules or tumours) for microscopic examination. A thin needle is inserted into the lesion, usually through the skin and often under ultrasound or CT-scan guidance, making this procedure much less invasive than a formal tissue biopsy.

Cytologic material received in fixative solution at the laboratory can also readily be prepared for further analysis utilizing special and immunoperoxidase stains, as well as numerous molecular pathology techniques (including human papillomavirus/HPV testing on cervical cytology specimens).

The pathologist’s primary role in the microscopic diagnosis of disease is crucial in guiding the clinician with further management and specific treatment of the patient.

The pathologist liaises closely with the patient’s clinicians, relying on clinical information, history and other laboratory results to direct the use of supplementary tests, such as special histochemical and immunohistochemical stains, as well as modern molecular (genetic) pathology tests, in order to arrive at a diagnosis as well as to assist in the staging of tumours and assessment of recurrence following therapy.