TP63 and neoplasm: In stroma-invasive (T1) tumours, p63 immunoreactivity was heterogeneous and dependent on histologic grade of the tumour; low-grade tumours showed a slightly lower incidence of intense staining than LPN tumours, whereas a majority of high-grade carcinomas showed weak or undetectable immunoreactivity, similar to muscle-invasive carcinomas (Figure 2).