Reticulate hyperpigmentation.

Disorders that are characterized by a reticulate pattern of pigmentation are reviewed. Dyskeratosis congenita (DKC) is the prototype of these. In addition to reticulate hyperpigmentation, mucosal leukoplakia, bone marrow dysfunction, cytogenetic instability, and a predisposition to malignancy are characteristic of DKC. The most common pattern of inheritance is X-linked, with heterozygous females showing variable expression, most likely depending on tissue-specific patterns of random X-inactivation. Other reticulate pigmentary disorders reviewed include the Naegeli-Franceschetti-Jadassohn syndrome, X-linked reticulate pigmentary disorder, dermatopathia pigmentosa reticularis, Dowling-Degos disease, dyschromatosis, confluent and reticulated papillomatosis of Gougerot and Carteaud, reticulate acropigmentation of Kitamura, and Revescz syndrome. Diagnosis, treatment, and sometimes genetic counseling remain problematic for these entities. The pathophysiology of these disorders is unknown, but will certainly be aided greatly by the future identification of the underlying genes.