Fig. 2

Pathology images. Panel a, b: Hematoxilin and eosin stain (panel a 20X magnification, panel b 40X magnification). NUT carcinoma typically shows sheets of monomorphic round to ovoid cells with scant pale eosinophilic to basophilic cytoplasm; nuclei with irregular outlines and slightly coarse chromatin with small nucleoli. Necrosis, mitotic figures and crush artefact are common. Panel c: diffuse nuclear immunohistochemical staining with nuclear protein in testis (NUT) antibody (40X magnification). NUT (C52B1, CELL Signaling, Technology) Rabbit mAb detects endogenous levels of total NUT protein. The antibody also detects levels of BRD4-Nut fusion protein. Panel d: FISH showing positivity for NUT-BRD4 fusion gene. FISH was performed using dual color single fusion probes: BAC clone (RP11-122P18) spanning NUT gene is labeled in spectrum orange, BAC clone RP11-637P24 covering BRD4 gene is labeled in spectrum green. The presence of the translocation t (15;19)(q14;p13) BRD4/NUT is showed by overlapping of one green and one orange probe signal (white arrows). FISH, fluorescence in situ hybridization; NUT, nuclear protein in testis; BRD4, bromodomain–containing protein–4; BAC, bacterial artificial chromosome