Abstract
Background:
Sarcoidosis is an immune-mediated idiopathic disorder and is generally thought to be a diagnosis of exclusion. Although researchers have looked at viruses, mycobacteria, and certain chemicals as possible triggers, the initiating antigen remains unidentified.
Observations:
A 41-year-old black male metal-worker previously diagnosed with systemic sarcoidosis presented with a 6-month history of recurrent, sometimes tender, skin nodules on the lower legs. Chest film, gallium scan, and angiotensin-converting enzyme (ACE) level results supported a diagnosis of systemic sarcoidosis. A biopsy of a lower extremity skin nodule showed confluent non-necrotizing granulomas with irregular birefringent particles in giant cells in a fibrous tissue background suggestive of a silica nodule. Review of a previous bronchial biopsy showed similar foreign body granulomas. Energy-dispersive spectroscopy (EDS) analysis of skin and lung tissue revealed mainly silica, clay (kaolinite), chromium, and aluminum particles that were consistent with the patient's occupational exposure.
Conclusions:
ACE level and gallium scan may not be specific for sarcoidosis. In certain occupational settings, EDS analysis should be considered before a diagnosis of sarcoidosis is made. This case may provide insight into the etiology of certain presentations labelled as sarcoidosis.
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