Multiple pulmonary nodules manifested in a patient with NK cell granular lymphocyte proliferative disorder

An 18-year-old man was admitted to our hospital with high temperature and dyspnea. A chest radiograph revealed the presence of multiple round nodules compatible with a metastatic lung cancer. The peripheral white blood cell count was 22,000/mm3 and more than 85 percent were atypical large lymphocytes with azurophilic granules. He was diagnosed as having natural killer (NK)-cell granular lymphocyte proliferative disorder (NK-GLPD) as the lymphocytes were positive with CD56, a cell surface marker characteristic for NK cells. The major pathologic finding of the tissue collected from the pulmonary nodules by transbronchial lung biopsy was infiltration of mostly large granular lymphocytes.