Presented are two cases of systemic mastocytosis in 46- and 63-year-old women, where the correct diagnosis was established in randomly disclosed cervical respectively intraabdominal lymphadenopathy. Both cases lacked characteristic skin and systemic mast-cell mediator symptoms at the time of histologic diagnosis. The first case was classified as a indolent systemic mastocytosis without any proven genetic alteration, the second one met the criteria of aggressive systemic mastocytosis with eosinophilia, where the point mutation asp816val in c-kit gene was confirmed and the patient responded unexpectedly well to Gleevec. Discussed are both conventional morphological differential diagnosis of mastocytosis in lymph nodes and recent advances in genetics of these systemic clonal mast cell proliferations. The latter not only outlines the oncopathogenesis but, in particular, also provides important prognostic and biological implications of this peculiar disease.