Pityriasis lichenoides is an acute or chronic lesion of the skin of unknown etiology, which is associated with a violation of the functioning of certain clones of T–lymphocytes. Symptoms of the condition are vesicular or papular rashes. Peeling of the skin is often observed, after the rash resolves, noticeable scars may remain. Diagnosis is made on the basis of the results of a specialist’s examination, examination of the patient’s anamnesis, biopsy and histological examination of the skin. Etiotropic treatment of the disease has not been developed, sunbathing and ultraviolet irradiation of the skin are used to eliminate the pathology, in some cases antibiotics and corticosteroids are prescribed.
General information
Pityriasis lichenoides (varioliform parapsoriasis, Mucha-Gaberman’s disease, Juliusberg’s teardrop-shaped parapsoriasis) is a dermatological disease of unknown origin, in which papular or vesicular rashes occur on the skin with the formation of scales and scars. Until recently, pityriasis lichenoides was considered one of the varieties of parapsoriasis discovered and studied by L. Brock in 1905, but now many dermatologists distinguish this pathology into a separate kind of dermatoses. The disease can occur in both acute and chronic forms – the first occurs more often in children, the second usually affects adolescents and adults. It is statistically established that men suffer from this condition more often than women. Pityriasis lichenoides can pose a potential threat to human health and life, because in some cases, like parapsoriasis, it transforms into malignant lymphoma of the skin.
Causes
The etiology of pityriasis lichenoides is currently poorly studied. It was found out that the main role in the development of pathology is played by T-lymphocytes with altered reactivity. At the same time, the acute form of the disease (PLEVA from pityriasis lichenoides et varioliformis acuta) is characterized by the presence of lymphocytes with CD8 receptors, whereas in the chronic type (PLC, pityriasis lichenoides chronica) only CD4 lymphocytes are detected. The immediate cause of such immunological disorders in pityriasis lichenoides is unknown, there are only theories, among which there are several of the most popular.
Autoimmune theory explains the development of this dermatological disease by a typical malfunction of the immune system, in which its cells begin to attack the body’s own tissues. This is confirmed by the participation of T-lymphocytes in pathological cutaneous manifestations of pityriasis lichenoides. Another theory of the occurrence of this condition is called infectious and considers the activity of certain microorganisms (bacteria and fungi) as the cause of pathology. It is possible both a direct effect on the skin of these pathogenic agents, and indirect – in the second case, pityriasis lichenoides develops due to the deposition of microbe particles in the skin or the occurrence of hypersensitivity. There are indications of the iatrogenic nature of the pathology, there are cases when the disease was diagnosed after taking certain medications.
Symptoms
There are two main clinical forms of pityriasis lichenoides – acute or PLEVA and chronic or PLC. The main difference between these two forms is the age of development and duration of the disease, there are also other differences. Acute pityriasis lichenoides (Mucha-Gaberman’s disease) occurs more often in children, sometimes it is registered in adults aged 20-30 years. The disease begins suddenly with the appearance of spots and papular-vesicular elements of pink color on the skin of the trunk and flexor surfaces of the extremities, which tend to merge. At the same time, fever, non-intense skin itching and headache may occur. Symptoms of acute pityriasis lichenoides reach their peak a few weeks after the first signs of the disease appear. In addition to papules and vesicles, scales of whitish or brown color are formed on the surface of the skin. Rashes resolve spontaneously or against the background of treatment and disappear over time, light scars may remain in their place.
Chronic pityriasis lichenoides (according to the old classification – Juliusberg’s teardrop-shaped parapsoriasis) is more often diagnosed in adult patients. Rashes usually appear on the skin of the palms, soles and extremities, less often a rash occurs on the trunk. In the chronic form of pityriasis lichenoides, the main elements of the rash are red or brown spots and vesicles, which are often injured with the exposure of erosive surfaces and the subsequent formation of crusts. Peeling of the skin is almost never detected, after the healing of erosions, white scars remain. Rashes with chronic pitiriasis spontaneously resolve after a few months, new rash elements often appear in their place. The disease can last for several years.
Diagnostics
Determination of pityriasis lichenoides in dermatology is carried out by methods of examination of the skin, observation of the course of the disease and histological examination of the affected tissues. Some secondary role in the diagnosis is played by immunological tests to exclude a number of infections: chickenpox, syphilis, dermatomycosis. On examination, characteristic vesicular or papular rashes are revealed, there may be light scars left after the resolution of the previous rash elements. In the case of acute pityriasis lichenoides, patients may complain of malaise, they have an increased body temperature.
The histological picture in pityriasis lichenoides is characterized by pronounced edema of the dermis with the development of infiltration of lymphocytes in it, which are determined by molecular immunological studies as CD4-T-lymphocytes (with PLEVA) or CD8-T-lymphocytes (in the case of PLC). There is an expansion of the capillaries of the skin, small hemorrhages and swelling of the vascular endothelium are possible. Keratocyte necrosis, ulceration and epidermal spongiosis are detected in the epidermis. There were no significant stable differences in the histological structure (with the exception of the type of lymphocytes in the infiltrate), according to which it would be possible to accurately differentiate between acute and chronic forms of pityriasis lichenoides.
Differential diagnosis of acute pityriasis lichenoides is necessary to exclude conditions such as chickenpox, herpes zoster, lymphomatoid papulosis, some forms of urticaria, scabies. For this purpose, conventional diagnostic methods are used: immunological, microscopic and others. Differential diagnosis of the chronic form of pityriasis lichenoides is performed with secondary syphilitic skin manifestations, flat and pink lichen.
Treatment, prognosis and prevention
Etiotropic treatment of pityriasis lichenoides has not been developed, for this reason, supportive and non-specific measures are used to treat this condition. In acute and chronic forms of the disease, patients are shown sunbathing, which can be replaced by ultraviolet irradiation of the affected foci. In the case of acute pityriasis lichenoides, especially with pronounced general manifestations (for example, fever), tetracycline antibiotics are used for treatment. With itching of the skin, corticosteroid ointments are prescribed, a good effect of coal tar-based products has been noticed, sometimes taking antihistamines helps. In some cases, with the typical course of pityriasis lichenoides, dermatologists do not prescribe any treatment, only monitor the disease and expect spontaneous resolution of rashes.
The prognosis of pityriasis lichenoides is favorable in most cases, even in the absence of therapeutic measures, the disease can resolve itself within a few months (PLEVA) or years (PLC). Nevertheless, patients are shown dispensary observation by a dermatologist with examinations every few months, since in some cases this pathology can degenerate into malignant lymphoma of the skin. This complication of pityriasis lichenoides is extremely rare and therefore does not significantly affect the prognosis of the condition as a whole. Preventive measures are reduced to timely treatment of foci of chronic infection in the body. In the presence of allergies and other pathological conditions of immunity, the exclusion of allergenic products, adequate and timely treatment of autoimmune diseases is shown.
