Spontaneous remission of acute lymphoblastic leukemia with mediastinal mass.

Spontaneous remission/regression of cancer is defined as partial or complete disappearance of malignant disease temporarily or permanently in the absence of medical treatment. This event is named as spontaneous regression for solid tumors and spontaneous remission for leukemia. The authors report the case of a girl aged 4 years and 3 months, who presented with mediastinal mass and leukemic findings in the bone marrow both of which reappeared after spontaneous regression and remission, respectively.