Linea nigra L81.9

Linea nigra is a characteristic form of asymptomatic, linear, cutaneous hyperpigmentation on the abdomen, usually extending from the umbilicus to the symphysis pubis. It is often observed as a physiological change associated with pregnancy.

In dark-skinned individuals of both sexes, a linea nigra may extend physiologically from the umbilical region to the mons pubis. This linear hyperpigemntation occurs (in contrast to white women) independently of hormonal influences and pregnancies.

In clinical studies in pregnant women, incidences of pregnancy-associated linea nigra of 32% to 92% are reported (Cohen PR 2023).

The development of linea nigra during pregnancy is thought to be caused by increased levels of oestrogen, progesterone and/or melanocyte-stimulating hormones. Linea nigra is not limited to pregnant women, but has also been observed in newborns and children. In addition, it has also been observed in men who had either benign prostatic hyperplasia or prostate cancer (Okeke LI et al. 2012).

Spontaneous remission in 80% of cases by the 8th postpartum month. In some cases, longer-lasting remission or residual findings remain.

1. Alkhowailed MS et al. (2021) Clinical Approach to Linear Hyperpigmentation: A Review Article. Clin Cosmet Investig Dermatol 14:23-35.
2. Cohen PR (2023) Linea Nigra: Case Report of a Woman With a Pregnancy-Associated Linear Streak of Cutaneous Hyperpigmentation on Her Abdomen From the Umbilicus to the Pubic Symphysis. Cureus. 15:e48408.
3. Okeke LI et al. (2012) Prevalence of Linea nigra in patients with benign prostatic hyperplasia and prostate carcinoma. Int J Dermatol 51 Suppl 1:41-43, 45-48.