Cutaneous hyperpigmentations are frequent complaints, motivating around 8.5% of all dermatological consultations in our country. They can be congenital, with different patterns of inheritance, or acquired in consequence of skin problems, systemic diseases or secondary to environmental factors. The vast majority of them are linked to alterations on the pigment melanin, induced by different mechanisms. This review will focus on the major acquired hyperpigmentations associated with increased melanin, reviewing their mechanisms of action and possible preventive measures. Particularly prominent aspects of diagnosis and therapy will be emphasized, with focus on melasma, post-inflammatory hyperpigmentation, periorbital pigmentation, dermatosis papulosa nigra, phytophotodermatoses, flagellate dermatosis, erythema dyschromicum perstans, cervical poikiloderma (Poikiloderma of Civatte), acanthosis nigricans, cutaneous amyloidosis and reticulated confluent dermatitis

An 8-month-old boy presented to the dermatologist for an evaluation of several cutaneous and skeletal abnormalities. Physical examination showed lobster claw deformity (ectrodactyly) of the right hand (Figure 1), hypoplasia of the left leg, and agenesis of the left foot, with areas of skin atrophy and hypopigmentation following Blaschko's lines (Figure 2). On the scalp, areas of patchy alopecia, with sparse hair and cicatricial aplasia cutislike areas could be visualized (Figure 3). In addition, anteroposterior cranial flattening and facial asymmetry were observed. On the left thigh, there were skin-colored exophytic nodules, areas of skin atrophy with hypopigmentation following Blaschko's lines (Figure 4). On the hand, papular exophytic lesions (papillomas) were observed in a linear arrangement, as well as nail deformities, such as longitudinal lines and fissures of the nail blades. On the trunk and extremities, areas of skin atrophy following Blaschko's lines could also be visualized, with punctate erosions within atrophic areas.On general examination, the baby had a normal psychomotor development for his age. Urologic abnormalities were found on imaging, including right renal agenesis, hypospadias, and bilateral cryptorchidism. Furthermore, a cardiologic examination revealed a ventricular septal defect and a patent foramen ovale. Genetic analysis showed a normal male karyotype (46, XY). There was no parental consanguinity, and no other family members were known to have a similar condition.