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Pigment retention (Bloch-Sulzberg melanoblastosis)
Last reviewed: 05.07.2025
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[ Causes and pathogenesis of pigment incontinence
Incontinence of pigment is caused by a mutant dominant gene located on the X chromosome. The gene is lethal to a male fetus. Women are mostly affected (90-95%), and the disease in men is considered to be a result of spontaneous mutation.
Histopathology of Bloch-Sulzberg melanoblastosis
Histologically, the first stage is characterized by the formation of vesicles containing eosinophils. In the epidermis, between the vesicles, single dyskeratotic cells are noted. Infiltrates consisting of lymphocytes and eosinophils are found in the dermis. The second stage is characterized by acanthosis, irregular papillomatosis and hyperkeratosis, the presence of numerous dyskeratotic cells. In the basal layer, there is vacuolization of cells and a decrease in their melanin content. In the dermis, a moderately severe chronic inflammatory infiltrate with a small number of melanophages is determined, penetrating into the epidermis in many places. The third stage is characterized by pigment incontinence. Penetration of pigment into the dermis and its accumulation in melanophages is noted.
Pathomorphology of Bloch-Sulzberg melanoblastosis
Morphological changes in the epidermis reflect the stages of the disease. Stage I is characterized by spongiosis with the formation of blisters containing neutrophilic and eosinophilic granulocytes and fibrin. Dyskeratotic cells may be located between the blisters. Stage II is characterized by hyperkeratosis with a large number of dyskeratotic cells, acanthosis, papillomatosis, vacuolar degeneration of the basal epithelial cells, and a large amount of pigment in the basal layer. The dermis is characterized by edema, lymphocyte, histiocyte, and neutrophilic granulopyte infiltrates. Warty elements are characterized by psoriasiform acanthosis, hyperkeratosis, and focal parakeratosis, while the dermis contains infiltrates of lymphocytes, plasma cells, and melanophages. As pigment spots form (stage III), the blisters disappear, inflammatory changes decrease, and there are many melanophages in the upper part of the dermis. In stage IV, zones of epidermal thinning, focal hyperkeratosis, and a decrease in the amount of melanin in the basal layer of the epidermis are detected; a small number of melanophages are located in the reticular layer of the dermis. Electron microscopic examination of the skin reveals an increase in the activity of melanogenesis in stages I-II of the process. Melanocytes have many processes, sometimes penetrating the dermis through the basal membrane. A second population of melanocytes is detected in the spinous layer. In the pigmentation stage, a large number of melanophages loaded with pigment are determined in the dermis; melanocytes are less active and contain autophagosomes. Melanin transport is impaired in epithelial cells. In stage IV, melanocytes are inactive, they are round in shape, without long processes. The number of melanophages in the dermis is reduced.
Histogenesis of pigment incontinence
The disease is based on a disorder of melanin synthesis and transport by melanocytes. At the beginning of the process, melanogenesis is enhanced, in subsequent stages it is noticeably reduced, and in stage IV of the process, melanocytes are functionally completely depleted, and the pigment accumulated in the dermis is gradually resorbed. Chromosome instability is noted. It is assumed that the gene is localized in the Xp11.2 region. The disease probably develops as a result of a deletion. Unlike the classical variant, the gene causing Ito hypomelanosis is located on chromosome 9-9q-33qter. The role of immune tolerance disorders is possible, due to which an autoimmune attack on clones of ectodermal cells with abnormal surface antigens occurs, or premature death of defective clones occurs. Chemotaxis of eosinophils in foci and lesions is probably due to the presence of leukotriene B4.
A special variant of pigment incontinence is reticular pigment dermatosis (syn. Frincheschetti-Jadassoni syndrome, reticular pigment dermatosis Naegeli), which usually manifests itself in the 2nd year of life, in persons of both sexes. An autosomal dominant type of transmission is noted. In this variant of the disease without an inflammatory stage, a stage of hyperpigmentation begins in the form of a mesh or spots located on the skin of the abdomen, neck, chest, in the area of skin folds. Diffuse or punctate keratoderma of the palms and soles is also characteristic. Patients do not have deviations in mental and physical development.
Hypomelanosis of Ito (achromatic variant of the disease) occurs in early childhood and is characterized by the appearance of foci of skin pigmentation, identical in outline and location to areas of hyperpigmentation in the typical form of pigment incontinence, but without the preceding two stages of the process. A distinction is made between cutaneous and neurocutaneous forms, which are inherited in an autosomal dominant manner. In the cutaneous form, the absence of pigment is observed in childhood. In the neurocutaneous form, in addition to pigmentation disorders, neurological disorders (mental retardation, convulsive syndrome) and bone anomalies are noted.
Differential diagnosis is carried out with enteropathic acrodermatitis, Werbow's syndrome, Albright's syndrome, hydrotic ectodermal dysplasia, in stage I - with bullous epidermolysis, herpes, epidemic pemphigus of newborns.
Symptoms of Bloch-Sulzberg melanoblastosis
The disease develops at birth or in the first days of life. There are several variants of pigment incontinence: the classic Bloch-Sulzberg variant, the reticular pigment Franceschetti-Jadassohn and Ito hypomelanosis. The classic variant is characterized by three stages successively replacing each other: bullous (inflammatory), papulo-verrucous and pigment.
The clinical picture depends on the stage of the process. Initially, from birth or, less often, in the first days or weeks of life, erythematovesicular, papulovesicular rashes appear, located mainly on the lateral surfaces of the trunk and proximal parts of the extremities with a tendency to a striped arrangement (stages I-II). Some elements acquire a warty character. After the rash regresses (stage III), pigmentation remains in the form of characteristic "splashes", "swirls" and stripes. Over time, hyperpigmentation gradually gives way to mild atrophy, sclerosis and depigmentation (stage IV). The staging of the disease is sometimes poorly expressed, bullous, papular and pigmented foci may exist simultaneously. Stage III often appears without previous symptoms. This may be the case if stages I and II occurred during the prenatal period or were erased and remained unnoticed. In addition to skin changes, most patients have various ecto- and mesodermal defects: dental anomalies, hypotrichosis, nail dystrophies, changes in the eyes, skeleton, and central nervous system. Variants of this disease include bullous keratogenic and pigment dermatitis, or Asboe-Hansen syndrome, Naegeli reticular pigment dermatosis, or Franceschetti-Jadassohn syndrome, and a colorless form of pigment incontinence - Ito syndrome, which is not indisputable. The existence of transitional forms is indicated.
The bullous stage (I) of the disease begins at 1-2 weeks of life and is characterized by a rash of vesicles and blisters on an erythematous base, papulovesicular and urticarial elements. The process is localized mainly on the extremities, lateral surfaces of the body. The rash is located linearly, symmetrically or grouped. The contents of the vesicles are usually transparent, when they open and dry, small erosions and crusts are formed. The elements of the rash appear in attacks, spreading to new areas of the skin. In most patients, the general condition is usually not disturbed. Eosinophilia is detected in the blood.
The papuloverrucous stage (II) develops approximately 4-6 weeks after birth and is manifested by the formation of keratinizing, hyperkeratotic papules, pustules, warty growths, located linearly in the area of former vesicles, or randomly. These skin changes persist for several months. Diffuse hyperkeratosis develops on the palms and soles.
The pigment stage (III) usually develops 3-6 months after the onset of the disease and is characterized by the appearance of brownish-yellow spots, hyperpigmentation with lighter edges of irregular outlines ("dirt splashes") at the site of resolved foci. These branched, linear patterns are located mainly on the skin of the abdomen and, less often, the extremities. Sometimes the papulo-verrucous and pigment stages can be observed simultaneously. Over time (15-20 years), mild atrophy and hypopigmentation develop at the site of hyperpigmentation, which some authors distinguish as the fourth - atrophic stage of the disease. At this stage, various exodermal and mesodermal changes, ophthalmological pathology (strabismus, nystagmus, cataracts, optic nerve atrophy, retinal detachment, keratitis, bluish sclera, iris pigmentation anomalies), neurological changes (seizures, epilepsy, oligophrenia, spastic paralysis such as tetra- or paraplegia), diseases of internal organs and the musculoskeletal system, dystrophy of nails and hair can be observed.
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Treatment of pigment incontinence
There are no effective methods of therapy. In the first stage, small doses of corticosteroids are recommended. In the stage of warty growths, neotigason is effective. Aniline dyes, epithelializing, anti-inflammatory drugs and agents that improve tissue trophism are used externally.