David B. Mosher

Monobenzylether of hydroquinone.: A RETROSPECTIVE STUDY OF TREATMENT OF 18 VITILIGO PATIENTS AND A REVIEW OF THE LITERATURE

Of 18 severely afffected vitiligo patients who used 20% monobenzylether of hydroquinone (MBEH, Benoquin) as a depigmenting agent, 8 achieved complete depigmentation after 10 months or more of use and 3 dramatic but no complete hypopigmentation. The 3 patients with no results did not use MBEH for more than 4 months. Complications were frequent particularly among those who did well, but only 1 case of contact dermatitis limited therapy. All patients who depigmented fully were very pleased with their results. As depigmentation induced by MBEH is generally irreversible, MBEH use must be reserved for induction of complete depigmentation of severely affected vitiligo patients who cannot or do not choose to repigment and who can accept the permanence of never tanning. The history, histology and mechanism of MBEH depigmentation are discussed.

Leukoderma Acquisitum Centrifugum: Halo Nevus and Other Hypomelanoses Associated with Neoplasms

The term “leukoderma acquisitum centrifugum” is a somewhat generic one commonly used synonymously with “halo nevus” but applicable to various tumors, including primary or secondary melanomas, surrounded by leukoderma (Table 119). This entity has been described as “leukopigmentary nevus” [2], “perinevoid vitiligo” [3], and “perinevoid leukoderma” [4]. While leukoderma acquisitum centrifugum applies to all nevi surrounded by a macule of leukoderma, the term “halo nevus” is restricted to nevus cell nevus.

Genetic and Congenital Disorders

Genetic and Chromosomal Disorders Single-Gene Disorders Autosomal Dominant Disorders Autosomal Recessive Disorders X-Linked Disorders Multifactorial Inheritance Disorders Chromosomal Disorders Alterations in Chromosome Duplication Alterations in Chromosome Number Alterations in Chromosome Structure Disorders Due to Environmental Influences Period of Vulnerability Teratogenic Agents Radiation Chemicals and Drugs Infectious Agents This chapter provides an overview of genetic and congenital disorders and is divided into three parts: (1) genetic and chromosomal disorders, (2) disorders caused by environmental agents, and (3) diagnosis and counseling.

Approach to the Problem of Leukoderma

The study of diminished skin color requires a special vocabulary. Various terms have been used to refer to decreased melanin content in the skin. These terms are intended to be purely descriptive and not to imply any one particular diagnosis or disease entity.

Skin Color and the Melanin Pigmentary System

The skin is a complex organ system endowed with the capacity to undergo a wide array of color changes. Normal skin color arises from a mixture of red, blue, yellow, and brown colored pigments (Fig. 1). In normal skin, melanin is the major pigment or color determinant and imparts a color ranging from a very light tan to a deep brown or black, depending on the quantity of melanin in the epidermis. A yellow hue may be imparted by carotenoids, red by oxygenated hemoglobin in the capillaries, and blue by reduced hemoglobin in the dermal venules and by pigment in the dermis.

Hypomelanosis Associated with Endocrine Disorders

The association of vitiligo with hyperthyroidism has been discussed (see “Vitiligo” in Chapter 1). Premature graying of hair may also accompany hyperthyroidism [1].

Hypomelanosis Associated with Inflammation

Hypomelanosis resulting from a wide variety of inflammatory dermatoses (Fig. 199) is a common problem in dark-skinned people [1] but may occur in many skin types. The most frequent causes of postinflammatory hypopigmentation include discoid lupus erythematosus, atopic dermatitis, eczematous dermatitis, chronic guttate parapsoriasis, lichen striatus, and probably pityriasis alba. The primary defect may be a pathologic change in the malpighian cells or increased keratinocyte turnover. A disturbance of transfer of melanosomes from melanocytes to keratinocytes is probably responsible for the pigmentary dilution.

Hypomelanosis Secondary to Irradiation and Physical Trauma

Melanocytes are vulnerable to nonspecific trauma. In animals or in humans, dark skin or hair may lose pigment in areas exposed to various types of injury (x-rays and ionizing radiations, ultraviolet rays, thermal burns, freezing, physical traumas) (Fig. 190).

Leukodermas without Hypomelanosis

Nevus anemicus, first described by Vorner [1] in 1906, is a congenital malformation characterized by macules of varying size and shape which appear distinctly pallid compared to the surrounding skin.

Infectious and Parasitic Hypomelanosis

Leprosy is a chronic and contagious human disease that mainly affects the skin and the peripheral nervous system, but which may also involve the mucous membranes of the upper respiratory tract, the eye, the superficial lymph nodes, the testes, and other organs. Hypopigmentation is one of the main cutaneous features of leprosy (Figs. 209, 210).