2.3. Immunohistochemistry

Histological assessment remains the cornerstone of clinical diagnosis, and immunohistochemistry (IHC) can aid with both diagnosis and prognosis [27]. For example, a panel of antibodies against PNL2, Melan-A, TRP-1, and TRP-2 are sensitive and specific to determine the melanocytic origin of amelanotic tumours [28], and IHC for Ki67 as a cell proliferation marker forms a clinically useful prognostic parameter [29]. IHC has also been extensively used in research to investigate protein expression, with additional visualisation of the spatial location of the protein. The availability of validated antibodies can be restrictive and there are no universal standardised scoring methods. However, semi-quantitative schemes are often based on the number of positive cells per high-powered field, and sometimes staining intensity is also assessed [30].