Eccrine poroma is one of the rare, mostly benign types of dermal tumors localized in the excretory duct of the eccrine sweat gland. It is usually located in the epidermal part of the duct. It is characterized by the presence of a slightly painful tumor-like elastic formation with a smooth glossy surface or papillomatosis of a burgundy-pink hue with a diameter of no more than 2 cm, protruding above the level of a healthy dermis. Nodes are more often found on the soles, less often on the palms and trunk, may have a lobular structure, include telangiectasia. The clinical diagnosis is established on the basis of examination, biopsy data, cytology. Treatment – radical excision of the tumor.
Eccrine poroma is a rare, usually solitary and intraepidermal neoplasm of the “pore” (excretory duct of the eccrine sweat gland), which gave the name of the tumor. It was described in 1956 by the American dermatologist G. Pinkus. There is no exact information about the prevalence of pathology and its share in the structure of dermatological diseases. Eccrine poroma has no gender component, the sex ratio is approximately equal.
Pathological neoplasm occurs mainly in patients older than 40 years, the disease does not have seasonality and endemicity. Solitary neoplasia is most often detected, but cases of multiple eccrine pores (up to 100 nodules) with localization on the soles of the patient are described. The urgency of the problem is connected with the possibility of transformation of a benign eccrine poroma into a malignant one.
The etiology and pathogenesis of the neoplasm have not been fully studied. The development of benign eccrine poroma is based on a simple hyperplasia of the epidermis cells of the eccrine sweat gland associated with exposure to an unknown trigger without visual damage to the nearby skin. Most often, the provoking factor of eccrine poroma is called radiation dermatitis, the usual exposure to ultraviolet rays and genetic mutation are not excluded.
Under the action of a pathogenic trigger, the cells of the epidermis of the excretory duct of the eccrine sweat gland are damaged. In response to damage, these cells trigger the mechanism of development of intraepidermal inflammation, followed by proliferation. At the same time, they produce mediators that activate the immune system. As a result, the development of proliferative processes and the formation of intraepidermal pathological nodes is noted.
The pathological process is slowly progressing. A pseudocapsule is formed, which excludes the penetration of the tumor into neighboring tissues, so a benign eccrine pore never metastasizes and does not undergo decay with the development of intoxication. Since eccrine poroma exists in benign and malignant variants, it should be borne in mind that the fundamental difference between a benign tumor is the absence of atypia in its structure.
With a malignant variant of eccrine poroma, atypia processes are observed in the epidermis and in the dermis. Neoplasm cells, for unknown reasons, lose their usual properties and begin to multiply uncontrollably autonomously, quickly infiltrating the gland and dermis tissue. They become flat, acquire unusual sizes and shapes.
The tumor, consisting of atypical cells, begins to spread to nearby tissues. Since an atypical cell differs from a normal one in its biological characteristics, the immune system recognizes it as foreign and destroys it. However, some of the atypical cells remain and continue to multiply. Inflammation occurs again, proliferation increases, biologically active mediators are produced, the immune system is activated, uncontrolled cell division continues.
In modern dermatology, the most important is the division of eccrine poroma according to the degree of malignancy. Distinguish:
1. A benign (pseudocapsular) form of pathology with no signs of atypia, which in turn is divided into:
- epidermal (simple, typical), localized in the area of the acrosiryngium (epidermal part of the duct of the eccrine gland);
- dermal (atypical), located in the thickness of the dermal duct of the eccrine sweat gland.
2. Pre-malignant (dysplastic) form with the appearance of signs of cell atypia, the beginning of autonomous proliferation.
3. Malignant (invasive) form with multiple atypical cells, metastasis processes, transformation into porocarcinoma.
The primary element is a node with a smooth or rough surface, which sometimes has a lobed structure and is located on a leg that thickens to the base. The diameter of the node is no more than 2 cm, the color is dirty pink or burgundy. On palpation, the tumor is elastic, sometimes slightly painful, has a tendency to slow growth. The typical localization of eccrine poroma is considered to be the skin of the soles, less often of the hands and trunk. At the same time, it should be borne in mind that eccrine poroma can be localized wherever there are eccrine sweat glands. The neoplasm may contain telangiectasia, in this case, when the skin is injured, bleeding occurs with a tendency to ulceration.
Variants of the occurrence of multiple nodes of eccrine poroma are described. The duration of the existence of pathological neoplasms ranges from several months to decades. Subjective sensations in the occurrence of eccrine poroma are initially absent. Clinical signs of malignant degeneration are considered to be causeless bleeding of the node with cortical formation, its soreness, itching, involvement of regional lymph nodes in the pathological process.
The clinical diagnosis is made by a dermatologist with the involvement of a surgeon and oncologist for consultation. Histological confirmation is mandatory for diagnosis. It is possible to perform microscopy of the cellular composition of the scraping from the surface of the pathological node of the eccrine poroma or its biopsy. In addition, a histochemical PAS reaction to glycogen is used.
Histologically, a distinctive feature of the tumor is the presence of immature epidermal cells filled with glycogen in the eccrine poroma area under study, as well as the presence of a large number of blood vessels in the tumor structure. The number of atypical cells determines the degree of malignancy of the eccrine poroma. Differentiate eccrine poroma with:
- pyogenic granuloma,
- seborrheic wart,
- basal cell carcinoma
- cell acanthoma,
- non-pigmented melanoma,
- eccrine spiradenoma,
- plantar wart.
Treatment of eccrine poroma of any form is radical. After consultation with a surgeon and oncologist, surgical excision of the tumor, laser evaporation, ionizing radiation therapy is possible. Benign eccrine poroma does not recur. With radical removal, the prognosis of any form of eccrine poroma is favorable.