Objective: This paper describes two different clinical presentations of diffuse cutaneous mastocytosis (DCM), based on the largest series published to date. As far as we are aware, these two variants of clinical presentations have not yet been reported. Design: We undertook a case controlled analysis of 8 children with DCM. Results of laboratory testing including mast cell mediator levels, and clinical symptoms on presentation and during follow-up were analyzed. Results: The levels of relevant mast cell mediators were initially high in all cases but declined sharply later on. There was a reduction of 20% in 2 of the 7 cases, whereas there was a reduction of 80% in the remaining 5. No reduction occurred in 1 case. Clinical improvement followed the same pattern. Conclusions: DCM is a rare variant of cutaneous childhood onset mastocytosis. Various forms show the same or overlapping features at various times. It appears to follow a course similar to that in other types of childhood onset mastocytosis, taking into account the decreased symptoms and the levels of mast cell mediators during follow-up. Obtaining a bone marrow biopsy should be considered only in those cases where there is no improvement or even worsening of signs or symptoms and persistent elevated levels of mast cell mediators.