PHAKOMATOSIS PIGMENTOKERATOTICA - REPORT OF NEW CASES AND FURTHER DELINEATION OF THE SYNDROME

Background: The epidermal nevus syndromes include different diseases t hat have the common feature of mosaicism. One of these has been recent ly identified and named phacomatosis pigmentokeratotica, in analogy to phacomatosis pigmentovascularis. It is characterized by an organoid n evus with sebaceous differentiation, a speckled-lentiginous nevus, and other associated anomalies. It has been hypothesized that this syndro me is caused by a particular genetic mechanism known as the twin-spot phenomenon. Observations: We describe 3 patients manifesting an associ ation of organoid nevus showing sebaceous differentiation and speckled -lentiginous nevus with associated anomalies and update the neurologic findings of a previously described patient. Hemiatrophy seems to be a common finding in all cases; hyperpathia, dysesthesia, and hyperhidro sis, as well as other neurologic defects, may be present. Conclusions: The findings in these patients allowed us to better delineate this sy ndrome. Further studies are needed to elucidate the underlying genetic defect. At present, however, the hypothesis that best explains this p henotype is twin spotting. Clinical recognition of this syndrome can c ontribute to the classification of the epidermal nevus syndromes and g ive insight into unusual genetic mechanisms occurring in humans.