Cytologic features and expression of D-type cyclins in cyclin D1-negative MCL. (A) Typical MCL cytology (case 1) (hematoxylin and eosin stain; original magnification, × 500); (B) cyclin D1 protein, showing only a rare nontumor cell with nuclear staining (case 1); (C) cyclin D2 protein, showing strong nuclear staining of the tumor cells (case 2); (D) cyclin D3 protein, showing strong nuclear staining of the tumor cells (case 4). Panels B-D are immunoperoxidase stains; original magnification, × 400. Figure S1 provides high-power photos of cytomorphology of other 5 cases.