Complex karyotype and absence of mutation in the c-kit receptor in aggressive mastocytosis presenting with pelvic osteolysis, eosinophilia and brain damage.

Aggressive mastocytosis is a form of systemic mast cell disease (SMCD) characterized by organ infiltration, bone lesions. eosinophilia and lymphadenopathies. Here we report a patient with unusual clinical features, namely osteolysis without other bone lesions commonly found in SMCD, major eosinophilia and cerebral infarction. The mast cells exhibited a classical immunophenotype (CD2+, CD9+, CD13+, CD25+, CD35+, CD45c+ and CD117+). Cytogenetic investigation showed novel complex aberrations, and clonal evolution was correlated with clinical progression. The screening for recurrent point mutations affecting the c-kit gene was negative. Mainly, the ASP816VAL substitution was not detected in our patient. Treatment with steroids and interferon was only temporarily effective.