Lethal Midline Granuloma in Okinawa with Special Emphasis on Polymorphic Reticulosis

Lethal midline granuloma (LMG) is a clinical term used to describe a condition which may be manifested histologically as Wegener's granulomatosis (WG), polymorphic reticulosis (PR), and malignant lymphoma (ML). WG is an inflammatory disease, and PR and ML are considered to represent a neoplastic proliferation of lymphoreticular cells. In this report, twenty‐two cases of LMG in Okinawa were examined. The frequency of LMG per 100,000 outpatients of the ear, nose and throat clinic in Okinawa was 67, and the higher frequency of PR (27) and ML (34) in Okinawa than in other districts of Japan was characteristic. Polymerase chain reaction, in situ hybridization, and immunohistochemical studies showed that the proliferating cells in PR were CD43(+) and simultaneously contained Epstein‐Barr viral genome in their nuclei. The higher frequency of PR and ML in Okinawa is discussed in conjunction with a review of pertinent literature: multiple factors including genetic, viral environmental, and socioeconomic factors seem to affect the frequencies of these diseases.