Particularly, a potential sign of tumour enlargement may be represented by the progressive elevation in ACTH levels, although they do not appear to linearly correlate with tumour progression, due to the short half-l ife and fluctuation of ACTH levels.28 However, the increase in ACTH levels, especially if substantial and rapid, may represent an alert to promptly perform imaging procedures.28 Here, POMC is linked to neoplasm.