AN OIL PIPE CLEANER OUT OF BREATH. D. Tran 1 , J. Wallace 1 ; 1 UCLA±San Fernando Valley Program, Sylmar, CA (Tracking ID #75804) LEARNING OBJECTIVES: 1. Recognize silicosis as a cause of pulmonary fibrosis. 2. Discuss the differential diagnosis of silicosis CASE INFORMATION: 25 y/o Hispanic male presented to ER for increasing dyspnea on exertion. His symptoms began insidiously about a year prior to admission, and have gradually worsened to the point where he can walk less than 1 block. His clinical course, thus far, has been punctuated by periods of exacerbation for which he was treated with antibiotics and prednisone with moderate success. He denies fever, chills, weight loss. There is no history of wheezing, asthma, chest pain, orthopnea, PND, or edema. The patient emigrated from Mexico three years ago. He denies any current or past of tobacco, drug abuse, or alcohol. On further questioning, the patient states that he spent three years in Mexico working as an oil pipè`c leaner''±which involved sandblasting. Physical exam and labs are only significant for a respiratory rate of 32 and paO2 of 70 mmHg at rest. CXR showed diffused bilateral infiltrates. High Resolution CT showed extensive, bilateral, coalescing pulmonary nodules with an upper lobe predominance and non-calcified hilar adenopathy. Patient is PPD and HIV negative. ACE level was 73 (9±67). He underwent video assisted thoroscopic lung biopsy. The pathology showed non-casseating granulomas with bifringent spicules consistent with sicilosis. Fungal and AFB cultures were negative. IMPLICATIONS/DISCUSSION: Silicosis is a type of pneumoconiosis caused by the inhalation of silica dust leading to pulmonary fibrosis. Individuals who work in metal mining or cutting, polishing, or carving stone are at risk. Symptoms usually develop after 3 to 20 years, depending on exposure level. Silicosis can either be simple: asymptomatic and non-progressive, identified by small, round opacities on chest x-ray; or complicated: symptomatic with progression despite discontinuance of the insults. Differential diagnosis includes sarcoidosis, coal worker's pneumonconiosis, neoplasia, TB, and fungal pneumonia. The diagnosis of silicosis is based on careful occupational history, radiographical evidences and pathology. Radiographically, silicosis is characterized by small, round opacities with an upper lobe predominance that can form extensive coalescing masses in advanced cases. The presence of eggshell calcifications on hilar lymph nodes may help distinguish silicosis from other pneumoconiosis. ACE level is elevated in sarcoidosis but can also be elevated in miliary TB, berylliosis, asbestosis, and silicosis. When the diagnosis is in doubt, biopsy can help establish the diagnosis and exclude other causes. On pathology, hyalinized silicotic nodules can be seen. They are formed by macrophages engulfing the particles, releasing cytotoxic enzymes causing fibrosis. There is a high incidence of TB co-infection in individuals with silicosis. Co-infection can be confused with a progression of the silicosis and should be excluded first. There is no effective treatment aside from preventing further exposure.