A healthy 1-month-old infant was referred to Dermatology for evaluation of abdominal hyperpigmentation that had been present since birth.
Physical examination revealed 7 hyperpigmented lines along the abdominal folds (Fig. 1A). No other abnormalities were observed in the mucosae, nails, or hair. A diagnosis of transient pigmentary lines (TPL) of the newborn (NB) was established, and the parents were informed about the benign and self-limited nature of the condition. At 13 months of age, the hyperpigmentation had almost completely disappeared (Fig. 1B).
TPL are included among the benign transient cutaneous lesions of the NB. It is a rare entity characterized by the appearance of hyperpigmented bands along the folds of the abdomen, back, or extremities. They are present from birth and progressively fade during the first year of life until complete resolution. Most cases have been described in Black male infants or those with dark phototypes. The main differential diagnosis is hyperpigmentation due to congenital adrenal hyperplasia. They have not been associated with any underlying disease, and their etiopathogenesis is believed to be related to intrauterine friction and hyperkeratosis of the folds due to the flexed position of the fetus.
