John's mole When he was 23, John noticed a dark mole on his right upper arm. At first he thought nothing of it, but over a period of weeks the mole became itchy and seemed to be getting bigger. He showed it to his doctor, who arranged for it to be treated in a dermatology clinic. The dermatologist removed the mole and sent it to the histopathology ladoratory. There it was sampled, processed and stained. The resulting microscope slides were examined by a histopathologist. He commented, "John did the right thing by going to the doctor straight away, since his mole was turning into a tumour - a malignant melanoma. This is one of the most aggressive tumours and can start to spread - usually with fatal consequences - even when it is only 1 mm thick. Fortuneately, John's tumour was still at an early stage, meaning that there is little risk of spread and removal is usually curative. Using our report, his doctors knew that no further treatment was necessary and were able to reassure him about the prognosis. Eight years later John is alive and well."

Understanding living tissue
Histopathologists are doctors who specialise in studying the changes caused by disease in human tissues.
Using sophisticated microscopes and a trained eye, they examine tissues and cells removed from patients in the clinic or at operation. By examining tissue sections which have been stained to reveal the microscopic structure, a histopathologist decides whether disease is present and, if so, what effect the disease will have on the patient. Many different stains are used to identify different tissue components and additional investigations involving electron microscopy or molecular biology are often helpful in selected cases.

Although some histopathologists specialise, like surgeons, in diseases of a particular part of the body, they all need a broad-based understanding of the clinical and pathological aspects of disease. Histopathologists are also the doctors who carry out autopsy examinations to establish the cause of death. Some of them specialise in forensic pathology, dealing with suspicious or criminal deaths.

Find out more about a career in Histopathology