Clinical Features of Extrapulmonary Sarcoidosis Without Lung Involvement

Abstract

Background: Compared with pulmonary sarcoidosis, sarcoidosis without lung involvement may involve other immunopathologic mechanisms and be associated with other demographic and clinical features.

Methods: This was a retrospective analysis of clinical data collected in real time on 1,686 patients with biopsy-proven sarcoidosis from two large university sarcoidosis outpatient clinics in the United States. We compared differences in demographics characteristics and clinical presentation between pulmonary and nonpulmonary sarcoidosis (NPS). Patients were considered to have NPS only if they had normal chest imaging and no features consistent with pulmonary involvement on the basis of currently accepted criteria.

Results: A total of 8.3% of this sarcoidosis cohort met criteria for NPS. NPS was significantly more common in white than black patients, and more common in women than men. The skin was the most common organ involved, and was observed in nearly one-half of patients with NPS. Isolated skin sarcoidosis was the overwhelmingly most common pattern of organ involvement seen in the NPS group (25%), and no other pattern of involvement was found in more than 5% of patients with NPS.

Conclusions: Significant demographic and sex differences were observed between patients with pulmonary and nonpulmonary sarcoidosis. These differences reflect previous data concerning differences between patients with skin and lung sarcoidosis because the skin was the major organ involved with NPS. Although the lungs are likely the primary site of exposure in pulmonary sarcoidosis, the high prevalence of skin involvement in NPS suggests the skin is the most conducive site of antigen capture outside of the respiratory tract.

Keywords: chest imaging; interstitial lung disease; sarcoidosis.