Fig. 1
a Cytology of a thyroid fine-needle aspiration showing a population of monotonous, medium-sized cells with little cytoplasm and a slightly irregular nuclear membrane (Giemsa-stained smear, ×40). b With Papanicolaou staining, some follicles, centered by liquid colloid, were evident and surrounded by the same population of medium-sized cells as in panel a (Papanicolaou-stained smear, ×20). c In the cell block preparation, the cells were identified as B lymphocytes and the majority stained for Mib-1 antibody (Ki-67 immunostain, ×40). d Whole body 18fluorodeoxyglucose positron emission tomography/computed tomography showing multiple disease localizations. Inset: focal uptake in the neck area corresponds to the left thyroid nodule (arrow) and to a neck lymph node (arrowhead). e A thyroid biopsy was necessary to confirm the diagnosis and showed the characteristic starry-sky pattern: a background of medium-sized lymphocytes studded with large phagocytic histiocytes with large nuclei and prominent nucleoli (hematoxylin and eosin stain, ×10). f Fluorescent in situ hybridization assay with a MYC Probe (Split Signal, Dako) of the thyroid biopsy. This probe set hybridizes the regions downstream and upstream to the c-Myc breakpoint cluster region with a red and green signal, respectively. Normal gene status is visualized by overlapping red and green signals. When a break occurs, red and green signals split, which is thus indicative of c-Myc translocation (see arrows)