LINFOMA DE CÉLULAS B GRANDES DIFUSO CON DOBLE EXPRESIÓN E INFILTRACIÓN ÓSEA: REPORTE DE CASO

Diffuse large B-cell lymphoma (DLBCL) can infiltrate the skeletal system secondarily, often presenting with nonspecific pain that complicates diagnosis. This report describes the case of a 48-year-old male patient with persistent pain in his left knee for three years, initially treated as hyperuricemia without improvement. Magnetic resonance imaging revealed a bone lesion in the tibia with soft tissue involvement and inguinal lymphadenopathy. Positron emission tomography combined with computed tomography (PET-CT) confirmed multifocal bone tumor infiltration. Biopsy revealed DLBCL with double expression of C-MYC and BCL-2 and a Ki-67 index of 90%. Treatment was initiated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), later intensified to R-DA-EPOCH. The patient showed good tolerance and clinical improvement.