NOTCH1 and neoplasm: We conducted an immunohistochemical study by performing NOTCH1, NOTCH2, NICD, and HES1 staining on the most representative formalin‐fixed paraffin‐embedded (FFPE) tumor tissues out of sixty‐two patients with the first diagnosis of either AFX (n = 33) or PDS (n = 29) in a single tertiary medical center.