We report the case of a 39-year-old male patient affected by type B Niemann-Pick disease, in whom pulmonary involvement became evident 15 years after the initial diagnosis. Pulmonary involvement was discovered incidentally during the evaluation of a dry cough and exertional dyspnoea which occurred in the context of an acute febrile, self-limiting illness. In this case, the pulmonary involvement is clinically mild, with minimal alteration of the diffusing capacity for carbon monoxide (DL(CO)), despite moderate fibrosis and widespread infiltration of both alveoli and interstitium by sea blue histiocytes.