Mastocytosis is characterized by an

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Aims: To investigate mast cell distribution in normal adult skin to provide a reference range for comparison with mastocytosis. Methods: Mast cells (MCs) were counted in uninvolved skin adjacent to basal cell carcinomas and other dermatological disorders in adults. Results: There was an uneven distribution of MCs in different body sites using the anti-tryptase monoclonal antibody technique. Numbers of MCs on the trunk, upper arm, and upper leg were similar, but were significantly different from those found on the lower leg and forearm. Two distinct groups were formedproximal and distal. There were 77.0 MCs/mm 2 at proximal body sites and 108.2 MCs/mm 2 at distal sites. Adjusted for the adjacent diagnosis and age, this difference was consistent. The numbers of MCs in uninvolved skin adjacent to basal cell carcinomas and other dermatological disorders were not different from those in the control group. Differences in the numbers of MCs between the distal and the proximal body sites must be considered when MCs are counted for a reliable diagnosis of mastocytosis. A pilot study in patients with mastocytosis underlined the variation in the numbers of MCs in mastocytosis and normal skin, but showed a considerable overlap. The observed numbers of MCs in adults cannot be extrapolated to children. Conclusions: MC numbers varied significantly between proximal and distal body sites and these differences must be considered when MCs are counted for a reliable diagnosis of mastocytosis. There was a considerable overlap between the numbers of MCs in mastocytosis and normal skin.

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.

We confirm the incidence of onset of mastocytosis previously reported in the literature. We conclude that childhood onset mastocytosis is much less transitory than generally is assumed, although improvement occurs in the majority of cases. Symptomatology and clinical course of adult onset mastocytosis is less severe than suggested in the literature.