What Happens in the Laboratory: Dermatopathology

Dermatopathology is the specialty of pathology in the skin. This is where the diagnosis of melanoma is made under the microscope, and is a critical component in the overall management of melanoma. The specimen that is cut out of the skin is processed in the laboratory onto small glass slides which are each careful examined for the signs of melanoma.

Once the diagnosis of melanoma is established, the specimens are then graded according to established melanoma risk factors to try and predict how badly the melanoma may behave. This importantly includes measuring the thickness of the melanoma which most accurately predicts risk. The edges of the specimen are also assessed to ensure that the melanoma has been completely removed.

Just as there has been improvement in the way melanoma is detected, dermatopathology has evolved with the development of new techniques to improve the accuracy of the diagnosis. The incidence of melanoma has been reported in some studies to have doubled over recent decades. This can be attributed to both an increase in the detection of melanoma, but also to an increase in the diagnosis of melanoma under the microscope. Over time we have learnt that some of the lesions previously thought to be benign have proven to behave like a melanoma. These are therefore now also diagnosed as melanoma.

Much goes on at the interface with the doctor in the clinic, but there is a lot of careful medicine going on behind the scenes in the laboratory. While it is hoped that improvements can be made soon in the treatment of melanoma, there have been many advances in the ability to diagnose it under the microscope.