Is hypothyroidism in idiopathic pleuroparenchymal fibroelastosis a novel lung-thyroid syndrome?

BACKGROUND: Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a rare type of interstitial pneumonia characterized by fibroelastosis. Patients with IPPFE as well as idiopathic interstitial pneumonia often have autoimmune diseases, which sometimes coincide with hypothyroidism (HypoT). However, there have been no reports on the association between IPPFE and HypoT. The purpose of this study was to evaluate the correlation between IPPFE and HypoT. We also examined the pathological features of the thyroid glands from autopsied cases.

METHODS: Thirteen patients diagnosed with IPPFE from among 255 consecutive cases of idiopathic interstitial pneumonia were included in this study; pertinent data were obtained from our hospital's clinical library. We examined the prevalence of HypoT and compared the clinical, radiological, and pathological features between the patients with and those without HypoT. Histological analyses of the lungs and thyroid glands were performed in 4 and 3 cases, respectively.

RESULTS: HypoT was identified in 7 of 13 patients (53.8%). Sex, body mass index, survival time, and laboratory test results were not significantly different between patients with and those without HypoT. Radiological and pathological lung findings were similar between both groups of patients. Thyroid gland histology demonstrated perifollicular or interlobular fibrosis without inflammation in all three cases, including a euthyroid case.

CONCLUSIONS: Although we only analyzed a small number of IPPFE cases, HypoT was prevalent among all of them. Characteristic fibrosis in the thyroid gland was observed even in a euthyroid case. Therefore, patients with IPPFE may potentially have thyroid gland dysfunction through a common pathogenesis in both organs.