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Postnatal Confirmation of Prenatally Diagnosed Trisomy 20 Mosaicism in a Patient with Linear and Whorled Nevoid Hypermelanosis
Author(s) -
Hartmann Anke,
Hofmann Uta B.,
Hoehn Holger,
Broecker Eva B.,
Hamm Henning
Publication year - 2004
Publication title -
pediatric dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.542
H-Index - 73
eISSN - 1525-1470
pISSN - 0736-8046
DOI - 10.1111/j.0736-8046.2004.21604.x
Subject(s) - trisomy , pathology , hyperpigmentation , aneuploidy , dermis , medicine , pigmentation disorder , karyotype , skin biopsy , biopsy , dermatology , chromosome , biology , genetics , gene
Linear and whorled nevoid hypermelanosis (LWNH) is characterized by hyperpigmented reticulate macules in a Blaschko linear arrangement without atrophy or preceding inflammation. Underlying chromosomal mosaicism was often assumed, but has been verified in only a few published cases. We report a 7‐year‐old boy with LWNH associated with congenital ventricular septal defect and psychomotor retardation. Prenatal chromosomal analysis of amniocytes revealed trisomy 20 mosaicism, which was not confirmed in peripheral blood lymphocytes after birth. Histologic sections of skin biopsy specimens taken at age 6 years showed hyperpigmentation of the basal epidermal layer with prominent melanocytes and isolated melanophages in the upper dermis. Cytogenetic analysis of cultured skin fibroblasts revealed an extra chromosome 20 in 5 of the 30 metaphases studied (17%). Mosaic trisomy 20 is one of the most common autosomal mosaicisms identified in amniocytes and is, as a rule, compatible with normal pregnancy outcome. In postnatal analysis of peripheral blood lymphocytes, an extra chromosome 20 could never be detected. However, when confirmed in skin fibroblasts, trisomy 20 mosaicism may be associated with systemic anomalies. The present case shows for the first time an association of LWNH with trisomy 20 mosaicism and emphasizes the importance of analyzing skin fibroblasts in cases of prenatally diagnosed trisomy 20.