Hypomelanosis of Ito in a case of trisomy 9 mosaicism (46,XX/46,XX,t(9;9) (p24;p24)): Spontaneous resolution of skin lesions during childhood

A 4 5/12 years old girl with hypomelanosis of Ito (HI) presented on the 3rd day of life with hypopigmented streaks and whorls following the lines of B laschko on the back, the arms and the legs. In addition, patchy depigmented areas were present on the trunk. Extracutaneous manifestations included dy stopia of the right kidney, atrial septal defect, persistent ductus arterio sus, hearing impairment, EEG abnormalities, and asymmetric dilatation of th e ventricle system and a vermal atrophy as documented in the MRT of the bra in. Cytogenetic analysis showed a mosaic 46,XX/46,XX,t(9;9) (p24;p24) prese nt in the lymphocytes and skin fibroblasts. The mother's karyotype in her l ymphocytes was normal. At reexamination at the age of 4 5/12 years the girl was retarded. In particular, the speech development was severely delayed. Interestingly we found only very small areas of hypopigmentation, which, un less one knew the previous findings, would not have been diagnostic.