Unsupervised hierarchical clustering demonstrated that myofibromas with ITDs segregate distinctly from conventional myofibromas and other pericytic tumours.<h4>Discussion and conclusion</h4>Our findings suggest that NOTCH3 ITDs represent a novel oncogenic mechanism in pericytic tumour pathogenesis, likely driving constitutive activation of the NOTCH signalling pathway. The gene discussed is NOTCH3; the disease is neoplasm.