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Hypomelanoses and Hypermelanoses at a Glance
  • Pigmentation disorders confront the clinician with a sometimes complex differential diagnosis, but can be approached logically as follows:
    • Congenital or acquired
    • Isolated or part of a syndrome
    • Diffuse or circumscribed
    • Epidermal or dermal
    • With or without inflammation
  • Altered skin pigmentation may be caused by the following factors:
    • Increased or decreased melanin
    • Abnormal melanin distribution
    • Decreased hemoglobin
    • Deposition of exogenous pigments

Pigmentation disorders of the skin can either be hypomelanotic, hypermelanotic, or may present with a pattern of mixed hypo- and hypermelanosis. The diagnosis of these disorders can be quite challenging. An algorithmic approach based on clinical features and history of pigmentary disorders is used throughout this chapter and serves as a guide for the clinician’ diagnosis and treatment (eFigs. 75-0.1 and 75-0.2) (Table 75-1, eTable 75-1.1).

Table 75-1 Differential Diagnosis and Management of Dermal Melanocytosis
eFigure 75-0.1

Algorithm for the diagnostic approach to hypomelanosis.

eFigure 75-0.2

Algorithm for the diagnostic approach to hypermelanosis. CALM = café-au-lait macule; LEOPARD syndrome = lentigines; electrocardiogram conduction defects; ocular hypertelorism; pulmonary stenosis; ...

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