COEXISTING SJOGRENS-SYNDROME AND SARCOIDOSIS IN THE LUNG

Context: Sjogren's syndrome (SS) and sarcoidosis are diseases of unkno wn origin that are considered to result from abnormal regulation of th e immune system. Pulmonary involvement by SS and sarcoidosis may have similar clinical and radiographic manifestations, making it difficult for the clinician to distinguish between these diseases. Objectives: T his study was undertaken to analyze the characteristics of SS and sarc oidosis in the lung to identify distinguishing features that may assis t clinicians in the differentiation of these conditions. Design: We pr esent two cases with severe pulmonary impairment in which the distinct ion between SS and sarcoidosis required lung tissue biopsy. The litera ture regarding the pulmonary manifestations of these diseases is revie wed. Results: The clinical, pathological, radiographic, and physiologi cal characteristics of lung disease in the setting of SS and sarcoidos is can be very similar, preventing a diagnosis solely on clinical grou nds. This is exemplified in the two cases reported. In one patient who carried the diagnosis of sarcoidosis, examination of lung tissue reve aled lymphocytic interstitial pneumonitis consistent with SS. In the o ther patient, who had previously been diagnosed with SS on clinical gr ounds, examination of lung tissue showed lymphocytic interstitial pneu monitis with scattered noncaseating granulomas, suggesting the possibi lity of coexisting SS and sarcoidosis. A literature review indicated t hat lung involvement by SS may be difficult to distinguish from that o f sarcoidosis. Furthermore, several cases have been reported in which both diseases coexisted. Conclusions: Because SS and sarcoidosis may c oexist and present with similar pulmonary manifestations, aggressive e valuation including tissue biopsy may be required. However, even tissu e biopsy may not distinguish between these entities unless noncaseatin g granulomas are seen (in the case of sarcoidosis) or isolated lymphoc ytic interstitial pneumonitis is detected (in the case of SS). When bo th features (ie; noncaseating granuloma and lymphocytic interstitial p neumonitis) are encountered in the same organ, we believe these diseas es are coexisting. Distinguishing both conditions may have prognostic implications, because sarcoidosis may present as an autolimiting proce ss and frequently resolves spontaneously without significant residual functional impairment. In contrast, pulmonary involvement with SS ofte n leads to permanent defects and may progress to incapacitating diseas e. Semin Arthritis Rheum 28:31-40. Copyright (C) 1998 by W.B. Saunders Company.