Immunophenotype of FL in children and young adults (cohort 1). (A) Case with BCL2 rearrangement and low PI composed of CD20+ (Ai), CD10+ (Aii) follicles with a low Ki67 PI (Aiii) that are BCL2 positive (Aiv). Higher-power image of BCL2 (Av) and CD3 (Avi) staining of the same area shows 4+ BCL2 staining intensity. (B) Case with no BCL2 rearrangement and with HPI composed of an expansile follicular proliferation of CD20+ (Bi), CD10+ (Bii) follicles with a high Ki67 PI (Biii) Ki-67 and with some expression of BCL2 (Biv). Higher-power image of BCL2 (Bv) and CD3 (Bvi) staining of the same area, showing 2+ BCL2 staining intensity. Panels Ai-ii, Aiv, Bi-ii, and Biv were captured at ×40 magnification and Aiii, Av-vi, Biii, and Bv-vi at ×200 magnification with the use of an Olympus, BX53 microscope, Olympus DP25 digital camera.