ABSTRACT
Purpose To investigate the clinicopathological features of primary subcutaneous lymphomatoid granulomatosis (LYG). Methods A case of primary subcutaneous LYG was observed by analysis of the clinical, histological features, immunophenotype and molecular pathology with review of the related literature. Results The male patient, 78-year-old, inadvertently found a mass of right axillary for more than 10 days. The boundary of the mass was clear, it seemed to have a capsule, the cut surface was grayish yellow and grayish red, the texture was medium. A large amount of coagulative necrosis was observed in the center of the mass under microscope. The peripheral area showed a morphological change of panniculitis, accompanied by pleomorphic lymphoid infiltration, showed central and vascular destructive infiltration, pathological mitosis was occasionally observed. Immunophenotyping showed that atypical large lymphoid cells expressed CD45 RB, CD20, CD30, while CD3, CD15, CD56, TIA-1, Granzyme B, ALK, CD21, Langerin and CD1 a, S-100 and CK (AE1/AE3) were negative. The proliferation index of Ki-67 ranged from 50％ to 60％. EBER in situ hybridization showed that positive cells were> 20/HPF.Neither acid fast staining nor TB-DNA testing supported tuberculosis. Molecular pathology found clonal Ig K gene rearrangement, TCRB + TCRG gene rearrangement showed the absence of monoclonal proliferating T cell population. Conclusion The primary subcutaneous LYG is a rare tumor. which can be diagnosed by combination of morphology, immunophenotype and molecular pathology.