An unusual presentation of pediatric acute lymphoblastic leukemia with parotid gland involvement and dactylitis.

Mumps infection during the course of childhood acute lymphoblastic leukemia (ALL) treatment has been reported to have a mild course and this was related to the intrinsic low cytopathological effect of the virus, contrasting with the severe course of measles and Varicella zoster virus infections in immunocompromised patients. Herein, we present a three-year-old girl, who was previously vaccinated against mumps infection, admitted with bilateral parotid swelling, dactylitis and serum immunoglobulin M positivity for mumps infection and diagnosed to have ALL with bilateral persistent parotid involvement, inconsistent with mumps infection. Acute leukemia should be suspected during the atypical course of any disease during childhood. Besides, mumps infection at presentation of ALL, as similar to infection emerging during the period of the leukemia treatment, has a mild course.