We report a case of endobronchial silicosis presenting with Right Middle lobe atelectasis.
78 year old white male admitted for non-STEMI. Workup showed occluded right coronary artery and a high-grade proximal LAD lesion. Echocardiogram showed moderate aortic stenosis with severely calcified leaflets.The patient had a brief smoking history and had worked in a foundry removing cooled metal from sand molds for 40 years. He had no prior PFTS. Up to his current illness he remained quite active. He did not travel or own any pets. Denied having fevers, chills, night sweats, weight loss, dyspnea, cough, hemoptysis, rashes, arthlagias, or swellingOn physical examination lung fields were clear. Cardiac exam revealed a grade 3/6 systolic ejection murmur.Chest x-ray showed linear atelectasis in the right middle lobe. (Fig 1). Figure 1. CT Chest showed a 2.9 cm right middle lobe consolidation with calcified thoracic adenopathy (Fig 2) Figure 2. On bronchoscopic examination, the orifice of the lateral subsegment of the right middle lobe was occluded as shown in the figure 3. Figure 3. Bronchial washing from the right middle lobe showed benign respiratory epithelial cells, alveolar macrophages, and chronic inflammation. Biopsy from the same region had unremarkable bronchial mucosa with single focus consistent with portion of silicotic nodule consisting of fibrosis, anthracosis, and rare linear polarizable particles consistent with silicosis. Fig 4. Figure 4. The patient underwent elective coronary artery bypass grafting and aortic valve replacement. The patient tolerated both procedures well and was successfully discharged to continue his rehabilitation at a specialized facility 11 days later.
Endobronchial silicosis is a known complication from exposure to silica however, very rarely seen. Only a few case reports have been identified dating back to the 1970’s. Affected patients are typically seen in regions of the world where underground mining occur and where melted metal are forged. Pittsburgh is such a region where a large population has worked in steel mills. Silica exists in both crystalline and amorphous forms. Amorphous forms include vitreous silica and diatomite which are relatively nontoxic after inhalation. In contrast, inhaled crystalline silica is associated with a spectrum of pulmonary diseases. A patient may be asymptomatic or presents only with an abnormal chest radiograph. Symptomatic patients commonly have chronic cough and dyspnea on exertion. Our patient was asymptomatic on presentation. Pathophysiology:Silica crystals translocate through the tracheobronchial-epithelial barrier into lamina propria of the bronchial mucosa to induce local pathological alterations. Silica can be phagocytized by macrophages, which are either expelled by mucociliary escalator or migrate into the bronchial mucosa. The nodular collections of silica-laden marcrophages and fibrosis can begin to protrude into the airway causing obstruction; termed endobronchial silicosis.
Silicosis is a common disease seen years after been exposed to Silica. Endobronchial silicosis is a rare finding in this disease. When present it is usually affecting the right middle lobe causing atelectasis and can be visualized on bronchoscopic examination.
Tariq Cheema, No Financial Disclosure Information; No Product/Research Disclosure Information