Hyperpigmented Lesion Following Blaschko Lines

HISTORY

A 4-year-old boy with asymptomatic hyperpigmented lesion on the left shoulder and left arm. The hyperpigmentation was first noted shortly after birth and had progressively enlarged until the child was 3 years old. The lesion has since increased proportional to body size. The child is otherwise healthy and developmentally normal. He takes no medication.

There is no past history of vesicular eruption and no family history of similar skin lesions. Parents are nonconsanguineous.

PHYSICAL EXAMINATION

Vital signs normal. Multiple hyperpigmented macules along the lines of Blaschko extend from the left shoulder to the left upper arm and forearm. Remaining examination findings unremarkable.

WHAT’S YOUR DIAGNOSIS?

ANSWER: LINEAR AND WHORLED NEVOID HYPERMELANOSIS 

Linear and whorled nevoid hypermelanosis is a rare skin condition characterized by linear streaks and swirls of macular hyperpigmentation along the lines of Blaschko.¹ The condition was first described in 1988 by Kalter and colleagues.² Synonyms include zosteriform hyperpigmentation, zosteriform lentiginous nevus, zebra-like hyperpigmentation, reticulate hyperpigmentation of lijima, and nevoid hyperpigmentation following Blaschko lines.^3,4

EPIDEMIOLOGY

Both sexes are equally affected.⁵ The occurrence is usually sporadic although familial cases have also been described.^3,6 The exact pathogenesis is unknown. Genetic mosaicism, leading to proliferation and migration of 2 populations of melanocytes with different potential for pigment production, is the most likely cause of this disorder.⁷

Histopathologic examination shows diffuse increased pigmentation in the basal layer and prominence of melanocytes without incontinence of pigment in the dermis.⁸

CLINICAL MANIFESTATIONS

The linear streaks and swirls of macular hyperpigmentation occur in a reticulate pattern without any preceding inflammatory or palpable verruciform
lesions.^1,4,8 Sites of predilection include the trunk and extremities. The pigmented streaks follow the lines of Blaschko and display a V-shaped pattern over the spine, an S-shaped or whorled pattern over the anterior and lateral aspects of the trunk, and a linear arrangement over an extremity (as in this patient) or genitalia.⁴ The palms, soles, scalp, and mucous membranes are typically spared.⁸

The hyperpigmentation usually appears within a few weeks of birth.¹ It tends to progress for 1 to 2 years before stabilization and usually persists indefinitely.^1,8

DIAGNOSIS

The diagnosis is typically clinical. Dermoscopy can be used to enhance the diagnostic accuracy of pigmented skin lesions.⁸

The differential diagnosis includes incontinentia pigmenti, hypomelanosis of Ito, and linear epidermal nevus. Incontinentia pigmenti almost always occurs
in girls and is generally fatal in boys; associated defects are present in 80% of patients. The cutaneous manifestations of incontinentia pigmenti usually progress through 4 stages.⁹ The first phrase presents with erythema, vesicles, and pustules; the second stage with verrucous lesions; the third stage with hyper-pigmented streaks or whorls; and the fourth stage with hypopigmentation, atrophy, and scarring. The hyperpigmentation that characterizes the third stage is present in most patients and usually fades by adolescence.

In hypomelanosis of Ito, the skin lesion consists of seemingly bizarre macular, hypopigmented streaks, stripes, whorls, and patches that conform to the lines
of Blaschko.¹⁰ The lesions always involve more than 2 body segments.

Linear epidermal nevus presents as skin-colored or brown, closely set, well-circumscribed, papules in a linear configuration. The lesion usually occurs on the trunk, neck, or an extremity and follows Blaschko lines. Linear epidermal nevus tends to become hyperkeratotic, papillomatous, verrucous, and hyperpigmented with time.

COMPLICATIONS

Linear and whorled nevoid hypermelanosis may be associated with growth retardation, developmental delay, intellectual disability, seizures, skeletal anomalies (eg, scoliosis, pectus excavatum, brachydactyly, body asymmetry), CNS anomalies (eg, hydrocephalus, macrocephaly, microcephaly, arhinencephaly), congenital heart diseases (eg, ventricular septal defect), and chromosomal abnormalities (eg, mosaic trisomy 7, 14, 18, and 20).^1,3,8

MANAGEMENT

There is no effective treatment for this condition. For lesions in cosmetically sensitive areas such as the face, skin camouflage creams are a useful option. 

REFERENCES:

1. Mehta V, Vasanth V, Balachandran C, Mathew M. Linear and whorled nevoid hypermelanosis. Int J Dermatol. 2011;50(4):491-492.

2. Kalter DC, Griffiths WA, Atherton DJ. Linear and whorled nevoid hypermelanosis. J Am Acad Dermatol. 1988;19(6):1037-1044.

3. Metta AK, Ramachandra S, Sadath N, Manupati S. Linear and whorled nevoid hypermelanosis in three successive generations. Indian J Dermatol Venereol Leprol. 2011;77(3):403.

4. Yuksek J, Sezer E, Erbil AH, et al. Linear and whorled nevoid hypermelanosis. Dermatol Online J. 2007;13(3):23.

5. Quecedo E, Febrer I, Aliaga A. Linear and whorled nevoid hypermelanosis. A spectrum of pigmentary disorders. Pediatr Dermatol. 1997;14(3):247-248.

6. Akiyama M, Aranami A, Sasaki Y, et al. Familial linear and whorled nevoid hypermelanosis. J Am Acad Dermatol. 1994;30(5, pt 2):831-833.

7. Di Lernia V. Linear and whorled hypermelanosis. Pediatr Dermatol. 2007;24(3):205-210.

8. Ertam I, Turk BG, Urkmez A, et al. Linear and whorled nevoid hypermelanosis: dermatoscopic features. J Am Acad Dermatol. 2009;60(2):328-331.

9. Leung AK, Kao CP, Robson WL. Incontinentia pigmenti in an infant. J Pediatr. 2006;149(1):138.

10. Leung AK, Robson WL. Hypomelanosis of Ito. Pediatr Rev. 2007;28(5):193-197.