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CONGENITAL HYPERMELANOSIS

LINEAR AND WHORLED NEVOID HYPERMELANOSIS

AT-A-GLANCE

  • Congenital diffuse streaky hyperpigmented macules in Blaschko lines.

  • Typically seen on the trunk and extremities.

  • No preceding inflammation or atrophy.

  • Onset in the first few weeks of life.

  • May fade with advancing age.

Linear and whorled nevoid hypermelanosis is a congenital condition causing diffuse streaky hyperpigmented macules along the lines of Blaschko.1

CLINICAL FEATURES

Linear and whorled nevoid hypermelanosis is characterized by widespread streaky hyperpigmented macules along the lines of Blaschko without preceding inflammation or atrophy in the first few weeks of life. Lesions are typically located on the trunk and limbs and do not cross the midline. Face, palms, soles, eyes, and mucous membranes are spared. Similar cases have been described under different descriptive names (zosteriform hyperpigmentation, zosteriform lentiginous nevus, zebra-like hyperpigmentation). Several cases have been reported with both hyperpigmentation and hypopigmentation. Pigmentary mosaicism is a useful term to encompass all these different phenotypes.

Rarely, extracutaneous manifestations, such as developmental and growth retardation, facial and body asymmetry, ventricular septal defects, and pseudohermaphroditism, are observed. The frequency of extracutaneous manifestations is unknown, as these observations have been made in case reports only.

ETIOLOGY AND PATHOGENESIS

Most cases are sporadic but the presence of mosaicism has been confirmed in a few cases (mosaic trisomies 7, 14, 18, and 20, and X-chromosomal mosaicism) by chromosomal analysis.2

DIAGNOSIS

In addition to the typical clinical appearance, histologic examination reveals increased pigmentation of the basal layer and prominence or vacuolization of melanocytes. Pigment incontinence is usually absent.

DIFFERENTIAL DIAGNOSIS

Linear and whorled nevoid hypermelanosis should be differentiated from incontinentia pigmenti (IP) and epidermal nevus.

CLINICAL COURSE AND PROGNOSIS

Kalter and colleagues1 described typical onset in the first few weeks of life with progression during the initial years of life. The pigmentation may fade gradually with advancing age.

INCONTINENTIA PIGMENTI

AT-A-GLANCE

  • X-linked dominant disorder resulting from mutation in the IKBKG (previously called NEMO) gene.

  • Lethal in male embryos.

  • Four clinical phases commencing at birth: vesicular, verrucous, hyperpigmented, and hypopigmented.

  • Congenital diffuse linear hyperpigmented macules in Blaschko lines.

IP, also known as Bloch-Sulzberger syndrome, was first described by Garrod and colleagues in 1906. It is an X-linked disorder primarily seen in females, which results in diffuse linear cutaneous hyperpigmentation.

CLINICAL FEATURES

Lesions usually proceed through 4 cutaneous stages, although the stages may sometimes overlap: (a) vesicular stage (from birth or shortly thereafter), which presents with multiple small and medium-sized vesicles following the lines of Blaschko; (b) verrucous stage (between 2 and 8 weeks of age) consisting of wart-like plaques; (c) hyperpigmented stage ...

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