Pigment International

REVIEW ARTICLE
Year
: 2014  |  Volume : 1  |  Issue : 1  |  Page : 13--16

Pigmentary demarcation lines


Nidhi Singh, Devinder Mohan Thappa 
 Department of Dermatology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India

Correspondence Address:
Nidhi Singh
Department of Dermatology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry 605 006
India

Abstract

Pigmentary demarcation lines (PDLs) are areas of an abrupt transition from hyperpigmented to hypopigmented or normal skin color. They are seen on limbs, face, and sometimes trunk. They are common in the black race. There are eight groups of PDL A to H. Facial PDL should be differentiated from melasma and postinflammatory pigmentation over the face. PDL are common in black women during pregnancy and are considered to be normal variants of pigmentation. Etiology of PDL continues to be an enigma and needs further research. PDL in pregnancy may regress spontaneously after delivery and do not require treatment. Facial PDL have a persistent course posing cosmetic concern for the patient and a challenge for dermatologist.



How to cite this article:
Singh N, Thappa DM. Pigmentary demarcation lines.Pigment Int 2014;1:13-16


How to cite this URL:
Singh N, Thappa DM. Pigmentary demarcation lines. Pigment Int [serial online] 2014 [cited 2019 Dec 11 ];1:13-16
Available from: http://www.pigmentinternational.com/text.asp?2014/1/1/13/135431


Full Text

 Introduction



Pigmentary demarcation lines (PDLs) are areas of an abrupt transition from hyper- to hypo-pigmented or normal skin color. They are seen on limbs, face, and sometimes trunk. They are more commonly reported in Japanese and black race and rarely in white races. [1],[2] There is a female sex predilection and PDL are more common in pregnancy. PDL was the first described in 1913 by Maztumoto. [3]

 Types of Pigmentary Demarcation Lines



These differential areas of pigmentation appearing as lines, which are referred to as PDL is due to differences in melanocyte distribution that may be influenced by multiple factors. Miura [1] was first to classify PDL into four Groups A to D by his observation in Japanese individuals, in 1951; later, in 1975 Selmanowitz and Krivo [2] classified PDL into five groups namely A to E. [2] Group A consisted of lines along the upper limb with variable trans-pectoral extension [Figure 1]. The lines along the lower limb were termed as Group B [Figure 2]. The lines on the chest and abdomen in the form of paired lines, median or paramedian were termed as Groups C. Group D PDL consisted of lines on the back, posteromedial demarcation. Bilaterally symmetrical, obliquely oriented, hypopigmented macules on chest were termed as Group E, which was the additional group added. Further demarcation of these PDL into subtypes has been described. The Group A lines have four subtypes I to IV and the Group C has two subtypes I and II as seen in the diagrammatic representation [Figure 3]. PDL on the face was first reported by Malakar and Dhar [4] in Indians, and they termed it as Group F. [4] Subsequently, Somani et al. [5] described Groups F, G, and H of PDLs on the face in Indians [Figure 4] and [Table 1]. [5] PDL Group F represents an inverted cone shaped area of hyperpigmentation over the lateral aspect of the face extending from lateral orbital rim inferiorly or inferolaterally. PDL Group G occurs at site similar to Group F, but with two inverted cones with a normal patch of skin in between two inverted cones forming letter "W"; PDL Group H occurs on the lower face as a linear hyperpigmented band extending from the angle of mouth to the lateral aspect of the chin. [5]{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Table 1}

 Etiopathogenesis



The etiology of PDL is unknown. Various theories have been proposed. PDL has been thought to coincide with the distribution of cutaneous nerve innervations. [1] Some consider it as an atavistic remnant, where skin over the dorsal aspect is more pigmented than the ventral aspect in order to provide better sun protection. [5] Racial differences in PDLs may be related to genetic variations as James et al. [6] in their population study found that 79% of black female adults and 75% of black men had PDL of at least one type and 15% of white females had one PDL. PDL Groups A and B were present in over 50% of the black women with PDL and Group C PDL was the most common in Black males. [6] Fourteen percent of black women had an appearance of new Group B PDL during pregnancy. PDL in pregnancy has been reported to be exclusively Group B. [5]

There are multiple reports of PDL in pregnancy, and many authors have tried to postulate the reason behind the appearance of PDL in pregnancy. [7] Compression of peripheral nerves originating at S1 and S2 levels of spinal nerves by the gravid uterus in later stages of pregnancy may obstruct the innervated cutaneous microvasculature resulting in increased pigmentation. Thus, they proposed that neurogenic inflammation in late stages of pregnancy may be behind PDL appearing in pregnancy. [7] However, skin biopsy has not revealed any findings of circulatory obstruction. Histopathological examination of the pigmented area has shown an increase in the basal layer pigmentation and few perivascular lymphocytes in upper dermis. [8] Thus, some authors suggest that the increase in pigmentation could be due to hormonal changes in pregnancy. Increase in hormones such as melanocyte stimulating hormone may trigger the inconspicuous melanocytes in areas of specific peripheral nerves leading to PDL in pregnancy. [8] PDL in pregnancy usually disappears after delivery. Generalized cutaneous hyperemia and PDL have been reported in pregnant women with a history of progesterone therapy in early pregnancy. [9] Decreased estradiol and elevated follicle stimulating hormone has been reported in a pregnant lady with Group B PDL. [10] The abnormal hormone levels returned to near normal after fading of PDL postdelivery. [10] However, the physiology of pigmentation in pigmentary disorders is thought to be related to increased levels of estrogens, or progesterone, or melanocyte stimulating hormone. [11]

Krivo [12] had proposed clonal-Blaschko linear theory to explain PDL and opined that PDL follow lines of Blaschko and are related to the pigmentary mosaicism. [12] However, Miura [1] had described that topography of PDL corresponded to axial lines of Sherrington and not lines of Blaschko or dermatome lines. These axial lines of Sherrington correspond to a subset of Voigt's lines. Voigt's lines separate dermatomes arising from nonconsecutive dorsal roots. PDL may become apparent only when subtle variation in pigmentation is apparent between two contiguous dermatomes originating from noncontiguous dorsal roots. During the development, different homeobox genes may be controlling sensitive nerve endings in neural territories and neural control of pigmentation may result in differences in melanogenesis noted across PDL. This is the axial neural theory proposed by Maleville, [13] which is better accepted than clonal-Blaschko linear theory. Nevertheless, some authors have recently proposed that cutaneous mosaicism could be responsible for facial PDL. Recently, Sarma et al. [14] analyzed PDL and Blaschko's lines over the face. They concluded that facial PDL F, G and H represent margins of patterned facial pigmentation and closely correspond to Blaschko's lines over the face. Mosaicism could explain familial aggregation, female preponderance in facial PDL and the presence of streaky or patchy pigmentation. [5] Thus, mosaicism may play a role in the development of PDL as initially proposed by Krivo. [12],[14] PDL has also been referred to as Voigt's line or Futcher's lines. [2],[9] PDL involving facial skin and oral mucosa has also been reported. [15] Family history of facial PDL has varied across studies from 61% in a study by Somani et al.[5] to35% in a study by Samary et al. [16] Thus, the etiology of PDL continues to be an enigma and needs further research.

 Facial Pigmentary Demarcation Lines



Facial PDL may appear around puberty and may persist without much change throughout life. They may have a genetic predisposition. [5] Facial PDL may be even present from childhood and goes unnoticed, only to become prominent after certain triggering factors like hormonal changes at puberty or pregnancy. Few other triggering factors for Group F PDL reported are acute illnesses such as typhoid, chickenpox, and viral hepatitis. Group F PDL may present as periorbital melanosis. On histopathology, both Group F PDL and periorbital melanosis have been found to have melanophages in upper dermis. [17] Facial PDL should be considered in the differential diagnosis of any facial pigmentation, especially if it is bilaterally symmetrical. Facial PDL present as bilaterally symmetrical, homogenous hyperpigmentation extending from lateral orbit or angle of mouth differentiating from melisma, which is usually blotchy and may occur at different sites such as forehead, nose, etc., than facial PDL. [16] Another close differential diagnosis of facial PDL is postinflammatory hyperpigmentation. The chronic course, well-defined margins and the absence of prior history of any skin lesions at the site would help in distinguishing facial PDL from postinflammatory hyperpigmentation. Facial PDL is underdiagnosed, and it is an evolving entity, which requires awareness among dermatologists. Facial PDL and familial periorbital melanosis may represent the same entity. [16]

 Pigmentary Demarcation Lines in Pregnancy



Pigmentary demarcation line is common in black women during pregnancy and is considered to be normal variants of pigmentation. [18] Around 14% of black women had developed Type B PDL in pregnancy "in a study which included both black and white races". [6] PDL has been reported to occur commonly in the third trimester of pregnancy. It usually appears after 7 th month of pregnancy and spontaneously fades in a few months after delivery. [8]

 Management



Pigmentary demarcation line in pregnancy may regress spontaneously after delivery and does not require treatment. Facial PDL has a persistent course posing cosmetic concern for the patient and a challenge for dermatologist. Kligman regimen along with strict photoprotection for 3 months for facial PDL has been reported to be a failure as it lead to a negligible color change. [5] Chemical peels for facial PDL have been reported to have some effect, but not long lasting. Six sittings of glycolic acid peels at 3 weekly intervals with starting concentration of 35%, which was increased gradually to 70% could result in only 10% decrease in pigmentation. After stopping the treatment, the pigmentation reverted back. [5] Q switched Alexandrite laser has been tried on PDL Group A on the anterolateral aspect of both arms and had satisfactory responded. [19]

References

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