Mastocytosis (pigmented urticaria)

Mastocytosis (synonym: pigment urticaria) is a disease based on the accumulation of mast cells in various organs of tissues, including the skin. Clinical manifestations of mastocytosis are due to the release of biologically active substances in mast cell degranulapia. The disease is rare, occurs in men and women equally, often in children (75%).

[1], [2], [3]

Causes and pathogenesis of mastocytosis

There is no single point of view regarding the origin of the pigment urticaria. It is considered as a consequence of benign or malignant proliferation of histiocytes, compared with histiocytosis, referred to the group of tumors of hematopoietic and lymphoid tissue (WHO, 1980). The role of the growth factor of the fat cells produced by fibroblasts and keratinocytes of other cytokines is assumed. Opinions are expressed on the nevoid nature of mastocytoma. The possible role of genetic factors is indicated by familial cases of the disease. There is no generally accepted classification. Usually distinguish skin, systemic and malignant (fat cell leukemia) forms.

In the development of mastocytosis, labrocytes (mast cells, mast cells) play an important role. In the lesion, mastocyte proliferation is noted. Subsequently, under the influence of immune (immune complexes, antibodies) and non-immune (drugs, heat, cold, friction, pressure, UV rays, emotional stress, food, etc.) activators, mast cell degranulation and release of histamine, peptidase, and heparin occur. Under the influence of these biologically active substances, there is an increase in vascular permeability, expansion of capillaries, venules and terminal arterioles, leading to a decrease in pressure, reduction of large blood vessels, stimulation of gastric secretion, etc.

[4], [5], [6], [7], [8]

Gistopathology mastocytosis

The peculiar coloring of the elements of mastocytosis of the skin is due to an increase in the epidermis of the number of melanocytes and the deposition of a significant amount of pigment in its lower rows, which, apparently, can be explained by the complex intercellular relationship between melanocytes and mast cells.

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Pathomorphology mastocytosis

Depending on the clinical picture, the histopathology of the skin in this disease varies. In the macula-papular and teleangiectic forms, tissue basophils are located mainly in the upper third of the dermis around the capillaries. They are few, and the diagnosis can be made only after staining with toluidine blue. Which metachromatic paints them in pinkish-lilac color.

When nodular or plaque ooze tissue basophils form large clusters of the type of tumor, infiltrating the entire dermis and even the subcutaneous layer.

Cells usually have a cuboid, less often - spindle-shaped form; their cytoplasm is massive, zozinophilic.

In diffuse mastocytosis in the upper part of the dermis there are dense ribbon-like proliferates from tissue basophils with rounded or oval nuclei and clearly defined cytoplasm. Tissue basophils with pigment urticaria are distinguished by a complex composition of the carbohydrate component, which includes heparin, sial-containing and neutral mucopolysaccharides, so they are stained with toluidine blue at pH 2.7 and give a CHIC-positive reaction.

With all the described forms of the pigment urticaria, with the exception of tedeangiectatic, eosinophilic granulocytes may be found among tissue basophils.

When forms of pigment urticaria, accompanied by the formation of bubbles or bubbles, the latter are located subepidermally, and in the old elements due to regeneration of the epidermis, intraepilermally. The blisters contain tissue basophils and eosinophilic granuloiitis. Pigmentapy in this disease is caused by an increase in the amount of pigment in the cells of the basal layer of the epidermis, less often by the presence of melanophages in the upper part of the dermis.

[11], [12], [13], [14]

Symptoms of mastocytosis

There are two forms of mastocytosis: skin and systemic. The cutaneous form is subdivided into generalized cutaneous (urticaria pigmented, persistent spotted telangiectasia, diffuse mastocytosis) and mastocytoma (a tumor, usually single).

Pigmented urticaria is the most common form of skin mastocytosis. At the onset of the disease, often in children, itchy pink-red spots appear, transforming into blisters over time. After blisters leave persistent stains brownish-brown color. In adults, the disease begins with the formation of hyperpigmented spots or papules. Spots and papules are flat, up to 0.5 cm in diameter, have a rounded shape, sharp borders and a smooth surface with no signs of flaking. They are located on the skin of the body, are few, have a light gray or pink-brown color. Over time, the papules spread to the other parts of the skin (upper and lower extremities, face), have a spherical shape, dark brown or dark brown color, sometimes with a pink-red shade. Often the process is suspended, remaining for many years, in the future it can progress with the development of erythroderma, affect the internal organs, which ends in death.

Pigment urticaria in children is benign. The disease begins with the appearance of itchy urticarial eruptions, which in a few years are transformed into papular elements. At the onset of the disease, blisters (vesicles) may appear on apparently healthy skin or on spots and papules differing in puffiness and a distinct pink-red shade. Clinically, pigmented urticaria in children has a distinct exudative component. Sometimes the elements disappear without a trace. The ignition phenomenon, or the Darya-Unna phenomenon, is important: when rubbed with fingers, a spatula, or a needle, the elements become swollen, pink-red coloring and itching of the skin intensify. The aggravation is noted after friction, pressure, thermal procedures (hot baths, insolations).

The skin form can manifest spotty-papular, bullous eruptions, diffuse, including erythrodermic, telangiectatic changes, and also quite rarely in the form of an isolated focus - mastocytoma. Most often there are small-blooded and papular rashes, spreading mainly in childhood. They are located mainly on the body, somewhat less often on the extremities, rarely on the face, they have round or oval outlines, reddish-brown color. After friction, the elements acquire an urtico-like character. At the same time there can be nodular formations, usually not numerous, with more intensive pigmentation. Expelling can coalesce, forming plaque and diffuse lesions, in rare cases become pachidermal in character with pronounced diffuse infiltration of the skin.

Persistent spotted telangiectotic form occurs in adults, resembles freckles outwardly, small telangiectasias are seen on the pigmented background.

For diffuse mastocytosis is characterized by thickening of the skin, which has a testovatuyu consistency, yellowish tint and resembles a picture of pseudoxantomy. There is a deepening of the skin folds. Foci are often localized in the axillary hollows, inguinal folds. On the surface of lesions may appear cracks, ulcers.

Also described are cystic and atrophic forms: the bubbles are tense, with transparent or hemorrhagic contents, acantholytic cells are absent in them, Nikolsky's symptom is negative.

Knotty mastocytosis occurs predominantly in newborns and children in the first 21 years of life.

Three types of nodular mastocytosis are clinically distinguished: xanthelasmoid, multi-nodular and knotty-confluent.

Xanthelasmoid varieties are characterized by isolated or grouped flat nodules, or knotted elements with a diameter of up to 1.5 cm, oval, with sharp boundaries. The elements have a dense texture, smooth or orange peel-like surface and a light yellow or yellowish-brown color, which makes them similar to xanthelasmas and xanthomas.

In case of multinodular mastocytosis, multiple hemispherical dense knotted elements with a smooth surface, which have a diameter of 0.5-1.0 cm, are pink, red or yellowish, are scattered throughout the skin.

The nodular-confluent variety is formed as a result of the fusion of nodular elements into large conglomerates located in large folds.

When nodular mastocytosis, regardless of its varieties, the phenomenon of Daria-Unna is poorly expressed or not detected. Urtikar dermographism is determined in the majority of patients. A characteristic subjective symptom is itchy skin.

In systemic mastocytosis, the internal organs are affected. The disease manifests itself in the form of mast cell leukemia (malignant form of mastocytosis).

Erythrodermic form, which is also rare, in adults, in contrast to children, occurs without bubble reactions.

Diffuse-infiltrative, gel-anesthetic and erythrodermic forms of mastocytosis are considered to be potentially systemic diseases.

Bullous mastocytosis develops in children in infancy or early childhood. Bubbles can be on the surface of maculopapular rashes or plaque foci, sometimes they are the only skin manifestation of the disease (bullous mastocytoe congenital), which is considered prognostically less favorable.

Solitary mastocytoma has the appearance of a small tumor-like formation or several closely located nodules, on the surface of which in children the formation of blisters is characteristic. The prognosis for this variant of the urticaria is the most favorable. In most cases, pigment urticaria, which developed in childhood, independently regresses to the period of puberty. On average, systemic lesions are observed in 10% of patients, mainly in the case of mastocytosis in adults.

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Differential diagnosis of pigment urticaria

Pigmented urticaria should be distinguished from urticaria with pigmentation, drug rash, skin reticulosis, pigmented nevus, histocytosis-X, xanthomatosis.

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Treatment of mastocytosis

Treatment of mastocytosis (pigment urticaria) is symptomatic. Recommend antihistamines. With the common skin process and severe course of dermatosis, glucocorticosteroids, PUVA therapy, cytostatics (prospidin) are used. External use of corticosteroid ointment.