The presence of sarcoid-type granulomata in peripheral lymph nodes, with no evidence of other typical lesions, doesn't allow to diagnose sarcoidosis. In fact, sarcoidosis is a systemic disease and two or more organs must be affected to reach a definitive diagnosis. However this involvement could happen even several years later, thus making a correct diagnosis really difficult. In the absence of other organ involvement, an "idiopathic granulomatous disease" of peripheral lymph nodes is identified. Patients must anyway undergo a careful, long-term follow-up in order to detect clinical or radiologic variations that may confirm a diagnosis of sarcoidosis. After presenting a case-report of monolateral adenopathy of the axilla as an idiopathic granulomatous disease, the Authors review the international literature about sarcoidosis and its extra-pulmonar presentation, underlining the importance of considering sarcoidosis among possible diagnosis when peripheral adenopathies occur.