Pigmentary demarcation lines in pregnancy

Lalit Kumar Gupta, CM Kuldeep, Asit Mittal, Vijay Paliwal, Himanshu Singhal, Kalpana Agarwal, Jaya Tantia

 Department of Dermatology, Venereology and Leprology, RNT Medical College, Udaipur (Rajasthan), India

Correspondence Address:
Lalit Kumar Gupta
24-C, Madhuvan, Opp. GPO, Udaipur-313 001 (Raj.)
India

Sir,

Pigmentary demarcation lines (PDL), also known as Futcher′s lines or Voigt′s lines, are physiological abrupt transition lines from areas of deeper pigmentation to the area with less pigmentation. These have most often been described in the skin of Africans and Japanese.[1] Five types (A-E) have been described. Malakar and Dhar (2000) were the first to report pigmentary demarcation lines over face in Indian population and labeled them as type F PDL.[2] Subsequently, a few more patterns of pigmentary demarcation lines on the face, types F, G and H have also been described in Indian subjects.[3] We report a pregnant woman, who presented with type B pigmentary demarcation lines and generalized cutaneous hyperemia.

A 30-year-old second gravida who was 8 month spregnant presented at the skin outpatient department with asymptomatic, broad, band-like pigmentation over the posterior aspect of both legs and thighs [Figure - 1], extending from the heel to the gluteal crease, that was present since 4 months. The medial borders of the pigmented areas were sharply demarcated while the lateral borders merged imperceptibly into the normal skin. She also had generalized cutaneous hyperemia that blanched completely on diascopy. She did not report similar pigmentation or hyperemia in her previous pregnancy. The patient underwent tightening of the os uteri during the first trimester for a patulous os and had a threatened abortion. She had also received progesterone injections for 3 months. These lines disappeared completely one month after parturition.

PDL are abrupt transition lines from areas of deeper pigmentation to areas with less pigmentation. They are rare examples of streaks of melanocytes, otherwise inapparent. They neither correspond to the lines of Blaschko that mark the distribution of linear nevoid conditions, nor to the dermatomal lines. These are most often observed in darker races and are considered to be normal variants of pigmentation.[4]

Five naturally occurring PDLs, labeled A-E, have been described:[1],[4], [5]

1. Type A (Futcher′s / Voigt′s lines), the most common lines, seen over the dorso-ventral aspect of the arms.

2. Type B, which appear during pregnancy on the lower limbs and regress after delivery.

3. Type C, which are mid sternal, extending from the clavicle to the inferior border of the sternum.

4. Type D, rare, postero-median lines along the spine.

5. Type E, periareolar hypopigmented macules.

In a recent Indian study, three distinct patterns of pigmentary demarcation lines have been described on the face and have been designated as F, G and H types of PDL.[3] The PDL were seen with a much higher frequency in women (9%) than in men (0.75%). Hormonal influence was suggested as a possible explanation for the higher occurrence in females. Type B pigmentary demarcation lines have been reported over the legs during pregnancy, and regress after delivery.[4] PDL seen in our patient typically correspond to type B lines.

The exact cause of pigmentary demarcation lines is still an enigma. They have been considered as an atavistic remnant, where the dorsal skin is pigmented more than the ventral, providing better protection from the sun.[5] Genetic and hormonal influences have also been suggested.[5] The PDL and generalized cutaneous hyperemia in our patient could possibly be due to the progesterone therapy received during early pregnancy. We could not come across a description of type B pigmentary demarcation line in the Indian literature.

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