[An adrenal neuroblastoma regression diagnosed and followed by ultrasound: a case report].

Neuroblastoma is an embryonal tumor of the sympathetic nervous system, arising during fetal or early post-natal life from sympathetic cells derived from the neural crest. A 9-day-old boy was diagnosed as adrenal neuroblastoma with liver metastasis by biopsy. After 6 years of follow-up with ultrasound observation, the boy presents a process of spontaneous recovery without any special treatment. Spontaneous regression of cancer is defined as the decrease in size or disappearance of a primary tumor or metastatic disease without therapeutic intervention. Neuroblastoma is known to show the highest rate of spontaneous regression among malignant tumors. A better understanding of the mechanisms for spontaneous regression might help to identify optimal therapeutic approaches for patients with these tumors.