[Mastocytosis in adults. Description of nine clinicopathological cases]

Mastocytosis is a hyperplastic process characterized by the infiltration of different organs and tissues by mature mastocytes. It is more frequent in childhood, although cases also occur in adults. There are significant differences between the ways mastocytosis presents in adults and children, as well as in its development and prognosis.

In this work, we describe the clinicopathological findings for 9 adult patients with mastocytosis. The clinical, evolutional and genetic characteristics of mastocytosis in adults are also compared to those of childhood mastocytosis.

In contrast with childhood mastocytosis, the skin lesions of adult mastocytosis are very monomorphous, and consist of macules and papules of less than 1 cm in diameter, brownish-red in color. There are few symptoms, and there is usually discrete pruritus. Darier's sign is very often negative. Furthermore, the skin lesions do not tend to spontaneously regress, which is what usually occurs in children. Finally, systemic involvement in adults is practically a constant, with mastocyte infiltration of the bone marrow in over 90 % of cases, and bone involvement in over 50 % of cases, while systemic involvement is rarer in children. In any case, even if there is infiltration of systemic organs in adult mastocytosis, there are usually no accompanying clinical symptoms. The mutation of the c-kit proto-oncogene consists of the replacement of Asp with Val at codon 816, and this is nearly always found in adult mastocytosis. It is less frequent in childhood mastocytosis.

All of these findings make it possible to classify adult mastocytosis as a separate clinicopathological entity from mastocytoses in children.