“…In our case, with the deposition of a large amount of dust, honeycomb changes and fibroblastic foci were observed in a lower lobe, which indicated fibrogenesis and are characteristic features of UIP [11]. In contrast to ordinary UIP, fibroblastic foci are uncommon and there are a limited number of reports of these foci among cases of interstitial pneumonia complicated by pneumoconiosis [12–17]; these patients were exposed to silicates [12, 13, 16, 17], asbestos [12, 15, 16], and hard metals, such as tungsten [14, 16]. Fibroblastic foci are composed of the accumulation of fibroblasts or myofibroblasts, which play a critical role in the progression of pulmonary fibrosis, and correlate with disease progression and a poor prognosis [18].…”