[A case of cervical progressive transformation of germinal center].

Progressive transformation of the germinal center is an unexplained borderline disease that presents as lymphadenopathy. The histological feature is an abnormally enlarged germinal center. Reports of this disease in otolaryngology are rare. A case of progressive transformation of the germinal center occurring in the bilateral multiple submandibular lymph nodes with swelling is presented. A 41-year-old man complained of bilateral painless cervical lymphadenopathy. Because fine needle cytology of the lymph nodes did not reveal any atypical cells, medical observation was performed. However, as the patient suffered from hoarseness, he consulted our hospital again. An otolaryngeal examination revealed mild enlarged bilateral lymphadenopathy. Removal of these lymph nodes to obtain a definitive diagnosis was performed. The pathological diagnosis was progressive transformation of the germinal center (PTGC). Immunostaining of the lymph nodes showed increased IgG4+cells (IgG4/IgG ratio=50%). To date, no significant changes in the cervical lymph nodes have been noted on follow-up. Because PTGC is apt to be misdiagnosed as Hodgkin's lymphoma, otolaryngologists should have full knowledge of PTGC.