[An autopsy case of neoplastic angioendotheliosis mainly affecting the lung and presenting with atypical cells in peripheral blood].

Neoplastic angioendotheliosis (NAE) is a rare condition characterized by proliferation of atypical cells in small vessels of various organs. In the past, atypical cells seen in this condition were considered to originate from vascular endothelial cells. However, recent immunohistochemical studies have established that the tumor cells in this condition mainly originate from B-lymphocytes. NAE is likely to affect the central nervous system and skin. Cases of NAE with a primary lesion in the pulmonary vessels are rare. One such rare case of NAE was recently encountered by us. The patient was a 77-year-old woman who was admitted to our department because of fever and interstitial shadow in both lungs. After admission, fever did not subside, and the pulmonary shadow became more marked. Laboratory tests upon admission disclosed elevated LDH. Of isozymes, LDH2 and LDH3 were high. Anemia and thrombocytopenia gradually became aggravated, and atypical cells with large basophilic cell body and irregularly shaped nucleus subsequently appeared in peripheral blood. Thereafter, the patient's general condition worsened rapidly and she died about 5 months after admission. Post-mortem examination revealed pleomorphic atypical cells filling the lumen of small vessels in various regions of the body. This finding was particularly marked in pulmonary vessels. With various immunohistochemical stains, these cells were identified as cells of B-lymphocyte origin.