[A case of interstitial pneumonia with smoldering adult T-cell leukemia].

A 66-year-old woman was admitted because of dry cough and dyspnea. Computed tomography showed ground-glass opacities and traction bronchiectasis in both lung fields. Then, ATL cells appeared in her peripheral blood, and the number of lymphocytes in BALF increased. Inverse PCR for HTLV-1 clonality of the peripheral blood revealed a polyclonal pattern, and she was given a diagnosis of smoldering adult T-cell leukemia. Using BALF flow cytometry, both CD4- and CD25-positive cells accounted for only 0.8%. Secondary interstitial pneumonia was diagnosed and we started therapy with prednisolone and cyclophosphamide. BALF flow cytometry may be useful in the differential diagnosis of ATL lung lesions.