| 137550 | |||||||||||||||
| GIANT PIGMENTED HAIRY NEVUS; GPHN | |||||||||||||||
| Alternative titles; symbols | |||||||||||||||
| GHPN; GCPN | |||||||||||||||
| Clinical Synopsis | |||||||||||||||
| TEXT | |||||||||||||||
| Description | |||||||||||||||
| Giant pigmented hairy nevus (GHPN) is a congenital melanocytic lesion, which despite its name may not be hairy. These nevi are significant because of the risk of malignant transformation (summary by Ho et al., 1999). | |||||||||||||||
| Clinical Features | |||||||||||||||
| Hecht et al. (1981) reported 2 first-cousin infants, a boy and a girl, respectively, who were born with giant pigmented hairy nevus of the scalp. The diameter of the nevi in each child approximated half of the scalp area, and the hair was dark in the center and of normal texture. Both infants showed normal development. Biopsies showed no evidence of malignancy. Ho et al. (1999) reported a girl with sporadic occurrence of GPHN. At birth, she was noted to have a large patch of dark, coarse, thick hair over the right temporoparietal region of the scalp extending to the right occiput. There was also a separate small 1-cm hairy nevus adjacent to the front fontanel, and 2 epidermal sebaceous nevi on the right temple. CT scan showed an absence of the cranial bone underlying the large hairy nevus, with a size of about 7 x 6 cm. The bony edges of the cranial defect were irregular. The skull defect showed gradual spontaneous regression over the next 2 years, and the patient had normal development and no seizures. Ho et al. (1999) postulated a dysregulation of growth at the cellular and extracellular matrix level resulting from paracrine effects. Stojanovic et al. (2000) reported a 21-year-old woman with extensive GPHN covering 20% of her total body surface. The lesions covered the trunk, upper and lower extremities, and the face. They were congenital, but there had been no changes in color, size, or distribution. Family history was negative. | |||||||||||||||
| Inheritance | |||||||||||||||
| Congenital giant pigmented hairy nevus usually occurs sporadically, but familial occurrence has rarely been reported. By studying the families of 3 patients, Goodman et al. (1971) found that each had relatives with multiple small pigmented nevi. The authors suggested autosomal dominant inheritance with variable expressivity. Voigtlander and Jung (1974) observed affected sibs, and Hecht et al. (1981) reported affected first-cousins with an one instance of male-to-male transmission. | |||||||||||||||
| Population Genetics | |||||||||||||||
| The frequency of occurrence of congenital giant pigmented hairy nevus larger than 20 cm in diameter in pediatric patients has been estimated to be 1 in 4,150. Data on possible malignant transformation of these lesions into a melanoma vary from 6 to 12% (Stojanovic et al., 2000). | |||||||||||||||
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