Keratoma is an age–related benign neoplasm of the dermis that occurs as a result of keratinization of the upper layers of the epidermis. It is manifested by the formation on the skin of single or multiple spots, plaques and nodes of different shades with a rough surface, prone to crust formation and spontaneous self-resolution. There are several types of keratomas that differ in symptoms and the likelihood of malignancy. The disease is diagnosed by a dermatologist or oncologist based on anamnesis and clinical manifestations using dermatoscopy. Additionally, histology, siascopy, ultrasound of neoplasms are performed. Treatment consists of anti-inflammatory and cytostatic therapy, radical removal of keratoma.
Keratoma is a single or multiple benign tumor–like skin lesion of hyperkeratotic origin. Some types of keratomas belong to borderline tumors, the appearance of which indicates the patient’s predisposition to oncological diseases. In the presence of such formations, there is a need for constant monitoring by a dermatologist or oncologist in order to exclude the possibility of spontaneous malignancy of benign neoplasia. Injury to keratoma by tight clothing contributes to the attachment of secondary infection, including viral and mycotic.
According to dermatologists, the first keratomas form on the skin of patients by the age of 40, the peak incidence occurs at the age of 60. Experts from the UK report that the pathological process occurs in 11% of cases in twenty-year-olds, in 25% of cases – in patients aged about 30 years. In Australia, keratomas are diagnosed in 45% of cases in patients older than 40 years, in 55% of cases – in young people. Dermatosis does not have a pronounced gender coloring, although some researchers note a more frequent development of keratomas in men. The urgency of the problem is related to the ability of some varieties of keratomas to malignant degeneration. According to various authors, malignancy is observed in 8-35% of cases.
The pathological process is polyetiological. The reason for the formation of neoplasms is, first of all, age-related dystrophy of skin cells. Pathology is caused by two mutually opposite processes – aging and stabilization of the vital activity of cells. The life span of each cell depends on the balance of these processes. With age, skin cells partially lose their ability to resist external negative factors, their RNA and DNA become vulnerable, the probability of tumor transformation increases, and there is a change in adaptive mechanisms.
The main trigger of keratoma is ultraviolet, the excess of which is neutralized by melanin. The pigment accumulates in the keratinocytes of the epidermis and is retained in the upper layers of the skin due to the cumulative effect. With age, melanin loses its ability to accumulate due to slowing down metabolic processes, while intracellular secretion of melanin in keratinocytes increases with simultaneous prevalence of hyperkeratosis processes. As a result, a keratoma is formed. The immune system also loses part of its protective and controlling functions with age, which leads to intensive growth of epidermal cells and, as a result, the formation of keratinization sites.
Genetic failures provoke the formation of keratomas. In addition, the appearance of neoplasms is stimulated by neuroendocrine pathology, a lack of vitamin A, a violation of the synthesis of sex hormones. Somatic diseases are important, which affect more than 70% of patients over 50 years old. Keratoma also occurs against the background of pathogenic effects on the skin of chemicals, juices of poisonous plants, long-term use of medications. In this case, the protective mechanisms of humoral and cellular immunity are activated, which through macrophages and T-lymphocytes, pro-inflammatory cytokines and interleukins activate inflammation with a predominance of proliferative processes and the development of hyperkeratosis.
Classification and symptoms
Benign hyperkeratotic neoplasms of the skin in dermatology are classified according to clinical manifestations and the degree of risk of malignancy. There are senile, seborrheic, horny, follicular, solar keratoma and angioceratoma.
Senile keratoma is the most common form of pathology, characterized by the appearance of single or multiple brown spots from 1 to 6 cm in diameter, localized in open areas of the skin. Formations tend to grow peripherally with a change in structure. Over time, the spot becomes convex due to infiltration and proliferation of individual areas of keratoma, loose, soft, sometimes a little painful to the touch. Later, the keratoma begins to peel off, follicular keratosis occurs inside the growing tumor with the formation of hair follicle cysts. Injury to the neoplasm leads to bleeding, attachment of secondary infection, inflammation. Senile keratoma can self-resolve or transform into a cutaneous horn, in connection with which there is a tendency to malignancy of the pathological process.
Seborrheic keratoma is neoplasia, a distinctive feature of which is slow growth with the formation of multilayer crusts in the absence of wetness. The pathological process begins with the appearance of yellowish spots up to 3 cm in diameter, localized on the chest, shoulders, back, scalp. Over time, due to the disruption of the sebaceous glands in the lesion, the spots become covered with loose crusty scales that easily detach from the surface of the neoplasm. Seborrheic keratomas rarely remain isolated from each other, they tend to cluster and peripheral growth. Together with them, the crusts increase in size, which begin to layer, become covered with cracks. The thickness of the crusty scales reaches 1.5-2 cm. The keratoma itself acquires a brown hue, its damage causes bleeding and soreness. There was no tendency to spontaneous resolution or malignancy.
Horny keratoma (cutaneous horn) is a rare tumor–like neoplasm of horn cells. Initially, a hyperemic area appears on the skin, in the area of which, due to the compaction of the epidermis, a hyperkeratotic convex tubercle is formed (up to 10 cm above the level of healthy skin), dense to the touch, with an uneven peeling surface and an inflammatory rim around the base. Most often, the cutaneous horn is a single neoplasm, but cases of multiple keratomas have also been described. Horny keratoma exists as an independent pathology or as a symptom accompanying other nosologies. It is localized on the face, in the area of the red border of the lips and genitals. A distinctive feature of horny keratoma is its spontaneous malignancy.
Follicular keratoma is located around the hair follicles. The first manifestation of pathology is a convex flesh-colored node with a diameter of no more than 1.5 cm with a rough surface. In the center of the formation, a cone-shaped depression is revealed, sometimes covered with scales. Keratoma is localized in the area of the location of hair follicles, most often on the face and scalp. Spontaneous malignancy is unlikely, but the tumor may recur even after radical removal.
Solar keratoma is a precancerous skin disease. The pathological process debuts with the appearance of many small flaky bright pink papules, which quickly transform into brown plaques with a wide inflammatory corolla on the periphery. The scales covering the plaques are whitish, dense, rough, but easily removed from the keratoma when scratching. Solar keratoma is localized mainly on the face. It has a tendency to spontaneous malignancy or spontaneous resolution of the pathological process, followed by the appearance of keratoma in the same place.
Angiokeratoma resembles a hemangioma, can be single or multiple. There are local angiokeratomas of the extremities, common papular neoplasia of the trunk and angiokeratoma of the genitals. The main element of the rash is a node from 1 to 10 mm in diameter of dark red, blue or black color (depending on the degree of participation of capillaries in the neoplasm). Nodes of irregular shape with blurred borders, peel off, tend to peripheral growth. Spontaneous resolution or malignancy is not observed.
The clinical diagnosis is made by a dermatologist based on anamnesis, symptoms of the disease and data from additional studies. The priority is oncological alertness. The appearance of a large number of keratomas on the skin, a sharp change in the color and size of neoplasms is a reason for consulting a dermatologist and taking a biopsy. Dermatoscopy, keratoma ultrasound, and siascanning are used in diagnostics. Differential diagnosis is carried out with warts, keratosis, papillomas, melanoma, basal cell carcinoma, nevi, Bowen’s disease, hemangiomas and lymphangiomas.
Conservative keratoma therapy consists in applications and local administration of cytostatics and antitumor antibiotics into the neoplasm in a hospital setting according to individual schemes. Intraocular injections of drugs based on a complex of acids are effective. Radical excision of keratomas is carried out with resistance to conservative therapy, suspicion of malignancy. Hair follicle curettage, laser keratomization, cryodestruction, electroknife, radiosurgery, traditional surgical excision of large elements (in case of malignancy – with adjacent tissues) are used. The prognosis with timely diagnosis and removal of keratoma is favorable. Regular observation by a dermatooncologist is shown.