Interstitial Pneumonia Developed in HTLV-I Carriers: Report of Two Cases

Two carriers of human T-cell lymphotropic virus type I (HTLV-I) with interstitial pneumonia are described. The first case, a 60-year-old man, was admitted with cough and dyspnea on exertion. Light microscopy of a lung specimen obtained by a transbronchial lung biopsy (TBLB ) showed thickening of the alveolar walls with infiltration of lymphocytes and fibrosis of the pulmonary parenchyma. Immunohistochemical analysis of the TBLB specimen showed positive staining in the lymphocytes for UCHL-1. This case was suspected as HTLV-I associated bronchiolo-alveolar disorder. The second case, a 74-year-old man, visited our hospital because of a persistent productive cough and dyspnea on exertion. Light microscopy of the TBLB showed a slight thickening of the alveolar walls and fibrosis of the pulmonary parenchyma with minimal infiltration of lymphocytes. Only 2.2% of the bronchoalveolar lavage fluid consisted of lymphocytes. The findings of the second case suggest that some factors other than T-lymphocytes may be related with the development of interstitial pneumonia in HTLV-I carriers. Interstitial pneumonia in HTLV-I carriers may be caused by as yet undiscovered mechanisms. A cohort study involving residents of an area where HTLV-I is endemic should be conducted to clarify the mechanism of pulmonary involvement in HTLV-I carriers.