BAP1 and neoplasm: Chromosomal aberrations, cytomorphology, nuclear BAP1 expression and circulating tumour cells (CTC) were analysed.<h4>Results</h4>Markers of poor prognosis, including monosomy 3, 8q gain, loss of BAP1 expression, and the presence of CTC, were detected in tumours as small as 3-4 mm in diameter and 1-1.5 mm in thickness.