Mastocytosis is a systemic disease caused by the proliferation of mast cells and their infiltration of the skin (skin form) and internal organs (systemic mastocytosis). There are five different skin manifestations: hyperpigmentation, small and large nodes, erythrodermic foci and telangiectasia. With any form of skin elements, a diagnostic sign characteristic is revealed – the Darya-Unna phenomenon. Treatment is mainly conservative and is carried out with serotonin inhibitors, histamine H2 blockers, cyproheptadine hydrochloride, cytostatics.
ICD 10
Q82.2 Mastocytosis
General information
Since mastocytosis is associated with the proliferation of mast cells, it has received a second name — mast cell leukemia. The disease is quite rare, its causes are still not known. According to statistical studies, about 75% of cases of mastocytosis occur in children under the age of two years. Moreover, every second such case of the disease is independently resolved during puberty.
Classification
Currently , dermatology distinguishes 4 clinical forms:
Cutaneous mastocytosis of infancy often develops in the first few years of a child’s life. Its distinctive feature is the complete absence of lesions of internal organs. As a rule, in the pubertal period, skin manifestations disappear and the disease passes. Only in some cases, infantile mastocytosis develops further with the transition to a systemic form.
Cutaneous mastocytosis of adults and adolescents is characterized by infiltration of mast cells not only of the skin, but also of internal organs: liver, heart, spleen, gastrointestinal mucosa, kidneys. However, unlike the systemic form of the disease, changes occurring in the internal organs do not progress with this form of mastocytosis. In some cases, cutaneous mastocytosis can turn into systemic.
Systemic mastocytosis develops mainly in adults. It is a progressive lesion of internal organs in combination with or without skin changes. Systemic form occurs in 10% of cases of cutaneous mastocytosis. At the same time, it usually develops after skin manifestations.
Malignant mastocytosis is caused by malignant degeneration of mast cells, from which it received the name mast cell leukemia. Altered mast cells infiltrate internal organs and tissues, which causes a rapid fatal outcome of the disease. Skin manifestations in this form of the disease are usually absent.
Symptoms
In about 50% of patients with mastocytosis, complaints relate only to changes in the skin. With mastocytosis with damage to internal organs, patients also complain of a periodic drop in blood pressure, attacks of paroxysmal tachycardia, an increase in body temperature and paroxysmal redness of the skin accompanied by itching.
Infiltrates from mast cells characteristic of the disease can accumulate in various layers of the skin, which causes a variety of skin manifestations. In this regard, there are five clinical variants of skin changes in mastocytosis.
Maculopapular variant is characterized by the appearance of multiple hyperpigmented spots or papules of small diameter on the skin. At the same time, individual lesions on the skin have clear outlines. The phenomenon of Darya-Unna is expressed — with mechanical action (for example, friction) on the spots, they turn into small bubbles, similar to skin changes in urticaria. Because of this feature, this variant of mastocytosis in some authors is found under the name pigmented urticaria.
The nodular variant is manifested by the appearance of multiple seals or hemispherical nodules in the skin up to 1 cm in diameter. The color of the nodules can be pink, yellow or red. Nodules can merge into plaques, the surface of which is smooth or orange peel-like. Large plaques usually have a bumpy surface. In the nodular variant, especially in adults, the Darya-Unna phenomenon is weakly expressed.
The solitary variant is manifested by the formation of a mastocytoma — a node of 2-5cm in size with a rubber consistency, wrinkled or smooth surface. Most often there is one node, but there are clinical forms with the formation of 3-4 nodes. In some cases, mastocytomas are combined with maculopappular rashes. The solitary variant develops exclusively with cutaneous mastocytosis of infancy. Its characteristic localization is the skin of the forearms, trunk and neck. When the surface of the mastocytoma is traumatized, bubbles or pustules appear on it (a positive phenomenon of Darya-Unna), and the child may complain of tingling in this place. The reverse development of solitary elements occurs suddenly, while mastocytomas sink in and smooth out with the surface of the skin.
The erythrodermic variant is diagnosed in cases when clearly delimited yellow-brown lesions with uneven edges and dense consistency are formed on the skin. Pronounced itching is characteristic. Cracks, scratches and ulceration form on the surface of erythrodermic foci over time. The most common localization is the folds between the buttocks and armpits. Darya-Unna’s symptom is sharply positive. Even a slight injury to the lesion leads to the formation of blisters and increased itching. When a large number of bubbles appear, they talk about the clinic of bullous mastocytosis. The erythrodermic variant of the disease rarely turns into a systemic form, but the progression of ulceration of its elements can lead to the development of erythroderma.
The telangiectatic variant is characterized by areas of red-brown skin lesions formed from telangiectasias located on a hyperpigmented background. The most typical lesion of the skin of the extremities and chest. The telangiectatic variant is observed mainly in adults and mainly in women.
Diagnostics
The characteristic symptoms and definition of the Darya-Unna phenomenon often allow the dermatologist to suspect mastocytosis. To confirm the diagnosis, a biopsy of the skin elements is necessary. Histological examination reveals infiltrates, which are an accumulation of mast cells. In the maculopapular and telangiectatic variant, mast cells infiltrate the upper layers of the dermis. With nodular mastocytosis, mast cells form dense infiltrates that capture almost all layers of the dermis. Solitary nodes or mastocytomas are characterized by the spread of infiltrate not only to the entire dermis, but also to the subcutaneous tissue. The erythrodermic variant is characterized by the formation of ribbon-like infiltrates from mast cells in the upper layer of the dermis.
In a clinical blood test, an increase in the number of basophils and neutrophils is determined with a sharp shift of the leukocyte formula to the left. If mastocytosis is suspected, urine histamine is also determined. However, the content of histamine in the urine increases not only with mastocytosis, but also with allergic or inflammatory diseases.
Systemic mastocytosis is diagnosed by determining 1-methyl-4-imidazolacetic acid, a metabolite of histamine, the content of which increases sharply in the case of systemic mastocytosis and remains within the normal range for cutaneous mastocytosis. When mastocytosis affects the internal organs, an ultrasound of the abdominal cavity reveals an increase in the liver and spleen. Approximately in 25-30% of patients with mastocytosis, X-ray examination and CT of the bone determine bone tissue disorders: osteosclerosis or osteoporosis.
It is necessary to differentiate mastocytosis with freckles, pigmented nevi, xanthomas. The nodular form is differentiated with dermatofibroma, and infantile mastocytosis is differentiated with pemphigus of newborns, congenital Rotmund-Thomson poikiloderma. In addition, mastocytosis must be differentiated from other diseases characterized by an increase in mast cells in samples for histological examination. Such diseases include lymphoma, hemangioma, lymphogranulomatosis, dermatofibroma, etc.
Treatment
In the treatment of mastocytosis, cyproheptadine hydrochloride, serotonin inhibitors, anti-allergic drugs (lemastine, cetirizine, fexofenadine), anti-inflammatory drugs (diclofenac, ibuprofen), PUVA therapy are used. With systemic mastocytosis, cytostatics are prescribed, with bullous manifestations — corticosteroids. Individual mastocytomas can be surgically removed.
Unfortunately, despite modern advances in medicine and pharmacology, existing methods of treating mastocytosis often turn out to be insufficiently effective.