Pathology of Interstitial Pneumonia Associated with Hypothyroidism — Report of Three Cases

Recently, idiopathic pulmonary fibrosis (IPF) associated with hypothyroidism was proposed as a possible link showing worse prognosis than IPF. We have reviewed our archives of interstitial pneumonias (IPs) and examined pathologic and clinical features of IPs associated with hypothyroidism to understand its variations. Pathologically, two cases showed usual interstitial pneumonia pattern, and one case showed non-specific interstitial pneumonia pattern. Small airway disease was a common histological feature in all cases. Two cases showed association with flavor of connective tissue disease (CTD). Diagnoses by multidisciplinary discussion for the three cases were IPF, unclassifiable IP, and systemic sclerosis associated interstitial lung disease. Our cases indicated that IPs associated with hypothyroidism may show not only IPF but also other histological types and probable connection to CTD. Furthermore, these three cases did not fit with predicted prognosis by histological patterns.