Mediastinoscopy in Patients With Presumptive Stage I Sarcoidosis: Conclusion
Sensitivity and Specificity of Mediastinoscopy
Our assumption of 100% sensitivity and specificity of mediastinoscopy favors the procedure. Mikhail et al reported a sensitivity of 88% for mediastinoscopy in patients with BHL in whom a diagnosis of sarcoidosis was thought likely. Lack of specificity is encountered in that small percentage of patients with systemic noncaseating granuloma and an identifiable etiology who display a clinical and radiographic picture not clearly distinguishable from sarcoidosis. Scadding reported the isolation of Mycobacterium tuberculosis in 18 of 230 (7.8%) patients with otherwise typical sarcoidosis. A small percent of persons with malignant neoplasms—most commonly, lymphomas and malignant myeloproliferative disorders (summarized by Reich)—have an associated systemic granulomatous process. In a cohort of 243 patients with sarcoidosis, 11 of whom had a malignancy, there was plausible evidence in 6 (2.5%) that the systemic granulomas were a response to the neoplasm. Thus, identification of noncaseating granuloma in lymph nodes retrieved at mediastinoscopy—even in a clinically and radiographically compatible setting—may be viewed as confirmatory, but not incontrovertible evidence of sarcoidosis. Respiratory Disturbance Index
Under observation, the diagnosis of SIS is self-revelatory: most cases will resolve within months to years; the remainder will exhibit stable BHL or develop characteristic pulmonary shadowing. Vigilant observation is necessary to recognize and deal with untoward developments. The rare patient with ABHL due to a clinically relevant AD will become evident in time. Biopsy specimen confirmation provides intangible benefits: in addition to immediate assurance that an AD has not been overlooked (particularly important when fear is incited by a radiographic interpretation listing neoplasia in the differential), it circumvents the risk of litigation for failure to diagnose and the appearance (in a man-aged-care setting) of curtailing appropriate medical care in response to financial inducements.
Though laudable in intent, a policy of routine mediastinoscopy in patients with BHLps, in a quest for immediate diagnostic certainty, does not withstand the test of patient benefit or cost containment. Vigilant observation is the preferred policy.