Kiil K, et al. - Researchers examined LP cells can express IgG4 and whether IgG4 immunostaining can be helpful in the differential diagnosis between nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and progressively transformed germinal centers (PTGC). They assessed 58 cases of PTGC and 56 cases of NLPHL using IgG4 immunostaining. Findings suggested that IgG4 immunostaining can provide additional knowledge in the diagnostic workup of cases with the differential diagnosis of NLPHL and PTGC. The outcomes proposed that IgG4’s inefficiency in clearing antigens might clarify why lymph nodes with PTGC are usually strongly enlarged and develop a high number of hyperplastic germinal centers. Polyclonal immunoglobulin heavy chain rearrangements in IgG4-positive plasma cells further supported the premise that PTGC represent a misled immune reaction.