Large plaque parapsoriasis is a type of Broca’s disease characterized by a large-focal skin lesion with a high risk of developing T-cell lymphoma. A symptom of this dermatological disease is the appearance on the skin of spots with a diameter of up to 10-30 centimeters of irregular shape with a predominant localization on the hips and trunk. The current is long. Diagnosis is carried out based on the results of examination of the patient’s skin and histological examination of tissues from lesions. Treatment includes antipruritic drugs, vitamins, corticosteroids and physiotherapy.
L41.4 Large plaque parapsoriasis
Large plaque parapsoriasis is a subspecies of the plaque form of the disease of the same name, both pathologies are combined under the common name “Broca’s disease”. In 1902, dermatologist L. Brock identified and combined into one group several varieties of dermatoses of unclear etiology, which he soon identified as parapsoriasis. After a certain time, another researcher P. Samman, the plaque form of the disease was divided into two clinical forms: small-plaque and large-plaque. These forms differ not only in the size of the lesions of the skin, but also in the prognosis of pathology, so some doctors distinguish benign (corresponding to small rashes) and lymphoma-prone (large-plaque) forms of plaque parapsoriasis. Thus, large plaque parapsoriasis is a less favorable type of Broca’s disease, which can transform into a malignant neoplasm. Pathology is more common in the elderly, male persons prevail among patients.
The etiology of large plaque parapsoriasis has been little studied and is largely unknown. According to some dermatologists, this condition has nothing to do with malignant lymphoma of the skin and is a type of dermatosis caused by immune disorders. At the same time, adherents of this theory recognize that long-term large plaque parapsoriasis can lead to the development of cancer. Experts see the causes of malignancy in lymphocytic infiltration of the dermis and epidermis in the lesions, where conditions can be created for the proliferation of defective clones of lymphocytes with the potential for unlimited reproduction.
Other researchers consider any plaque parapsoriasis as the initial stage of malignant skin lymphoma. To prove their theory, they cite data from immunological and cytogenetic studies indicating that in the lymphocytic infiltrate of the skin in the lesions, most T-lymphocytes have CD4 receptors, belong to the same clone and often show a tendency to atypical growth. Thus, large plaque parapsoriasis may not be a condition predisposing to malignant lymphoma of the skin, but its first manifestation. The disadvantage of this hypothesis is the lack of data on the mandatory degeneration of parapsoriasis into lymphoma. However, given the late onset of the disease, it can be assumed that not all patients survive to the manifestation of a malignant neoplasm.
There are other theories about the etiology and pathogenesis of large plaque parapsoriasis. In particular, there are indications of the influence of viral and bacterial infections, chronic skin lesions, metabolic disorders, immune disorders, severe allergies and endocrine diseases. Taking into account the many existing theories, today the most common opinion is about the polyetiology of this pathology.
The main manifestation of large plaque parapsoriasis are irregular spots measuring 10-30 centimeters on the skin of the trunk and limbs. Spots, as a rule, do not rise above the surface of healthy skin. In the initial stages, itching is usually absent, but may occur in the future, especially in the case of transformation of this condition into malignant lymphoma of the skin. Telangiectasia appears on the surface of foci of large plaque parapsoriasis, pigmentation disorders are possible. The skin looks atrophic, similar to tissue paper. After the appearance of spots, they can persist for many years without changes and the appearance of other symptoms.
A sharp acceleration of the formation of telangiectasias, the appearance of peeling, itching and papular rashes may indicate the degeneration of large plaque parapsoriasis into malignant lymphoma. In such cases, an urgent appeal to a dermatologist or oncologist is necessary to clarify the final diagnosis and early start of treatment. An indirect sign of malignant transformation is also an increase in infiltration of the skin – spots begin to stand out sharply against the background of unchanged skin, may protrude above their surface.
To determine large plaque parapsoriasis in dermatology, data from the examination of the patient’s skin and a biopsy of tissues from the affected areas are used. Upon examination, large (up to 10-30 centimeters) irregularly shaped foci with bran-like scales on the surface are revealed. The color of the spots varies from reddish and bluish to brown. The predominant localization is the hips and trunk. Rashes are more pronounced in places where the affected skin rubs against clothing or other parts of the body. Telangiextasia, vesicular eruptions, areas of hyper- or hypopigmentation may be detected on the surface of foci of large plaque parapsoriasis. If it becomes known from questioning that such symptoms appeared relatively recently and were accompanied by itching, this becomes a reason for consulting an oncologist about malignant lymphoma of the skin.
Biopsy and histological examination of the affected tissues reveals pronounced lymphocytic infiltration of the dermis with partial exocytosis of lymphocytes into the epidermis. Sometimes cavities filled with immunocompetent cells form in the thickness of the epidermis. Pronounced acanthosis and vacuole dystrophy of the cells of the growth layer of the epidermis are observed. The vessels of the dermis are sharply expanded, there is swelling of the papillary layer and other inflammatory manifestations. Cytological studies confirm that most lymphocytes belong to a single clone of T cells with CD4 receptors. Differential diagnosis of large plaque parapsoriasis is performed with atopic and seborrheic dermatitis, radiodermatitis and malignant lymphoma of the skin.
Treatment, prognosis and prevention
Therapeutic measures for large-scale parapsoriasis are reduced to desensitizing and supportive treatment. Elimination of foci of chronic infection (carious teeth, tonsillitis, sinusitis), endocrine disorders and metabolic disorders can play a certain positive role. Be sure to prescribe vitamin therapy using retinol, tocopherol and vitamins of group B. If necessary, antipruritic agents are used. In severe cases, ointments with corticosteroids are used externally. Physiotherapy has a beneficial effect on the skin of patients with large-scale parapsoriasis. Usually, ultraviolet radiation is used, which in some cases is enhanced by methods of PUVA therapy of psoriasis.
The prognosis of this dermatological condition is uncertain with a tendency to unfavorable. Large plaque parapsoriasis is difficult to treat, can become a precursor or act as the first symptom of fungal mycosis and large-cell lymphoma of the skin. All patients should be registered at the dispensary with a dermatologist and, possibly, an oncologist. Regular examination and careful monitoring of any changes in pathological foci will help to identify cancer at the earliest stage, when the chances of its elimination are very high.