In situ follicular lymphoma with progressive transformation of the germinal centers confirmed by laser capture microdissection, IGH gene rearrangement analysis, and fluorescence in situ hybridization for t(14;18).

The authors report an unusual case of in situ follicular lymphoma associated with progressive transformation of the germinal centers. The patient was a 74-year-old Chinese woman with sequential lymphadenopathy in the right and left cervical regions over a period of 2 months. The first biopsy revealed in situ follicular lymphoma with progressive transformation of germinal centers, and the biopsy of the second lymph node led to a diagnosis of in situ follicular lymphoma. The immunophenotype, polymerase chain reaction amplification of the immunoglobulin heavy chain gene, and fluorescence in situ hybridization for t(14;18) were analyzed in each biopsy specimen, which showed both specimens to have t(14;18)(q32;q21) and revealed progression from polyclonality to monoclonality. These findings suggest a case of multicentric in situ follicular lymphoma and provide new insights into the pathogenesis of this disease.