1) Idiopathic pulmonary fibrosis may be defined as an irregularly progressive pulmonary
disease of unknown etiology characterized clinically by dyspnea, chronic cough and
cyanosis in association with minimal lung findings, and pathologically by a startling degree
of wide-spread hyperplasia of the interstitial pulmonary connective tissue. 2) The brief
literature is reviewed and an additional case reported, the most remarkable feature of which
is the occurrence of a clinically indistinguishable condition in the patient's identical twin …