Cutaneous horn is a rare tumor–like formation of horn cells. It can occur independently or as a consequence of other benign formations (warts, papillomas) or malignant genesis (squamous cell carcinoma). Clinically, it is most often manifested by a single cone-shaped horn element on the inflammatory erythema at the base. Less often, the process takes on a widespread character, which violates the quality of life of the patient. The height of the neoplasm serves as a prognostic sign: the smaller the element, the more unfavorable the prognosis. It is localized mainly on the skin, the mucous membranes are rarely affected. It is diagnosed only after histological confirmation. The treatment is surgical.
General information
The cutaneous horn is a local hyperplasia of the epithelium, consisting of horny masses resembling a cylinder or horn of wild animals, having clear boundaries and an inflammatory process at the base. It has no gender and age differences. There is no information about the prevalence, endemicity of the process. The question of the independence of the disease is controversial. In dermatology, the concept of “skin horn” is considered to be collective, since it can be a consequence of many tumor processes, but more often serves as a marker of precarcinous proliferation of the epidermis, developing as a result of actinic, senile keratosis, degenerating into squamous cell skin cancer.
The skin horn was studied by many representatives of various dermatological schools. German dermatologists in the person of Corting, Denk suggested that the basis of the skin horn are changes in collagen at the molecular level, followed by a failure in the differentiation of dermis and epidermis cells. The Greek doctor Higamenakis noted a hereditary predisposition to the development of the disease, which, in combination with provoking moments, leads to the appearance of a skin horn. However, there is no consensus on this issue today. The urgency of the problem lies in the close connection of such hyperkeratinization processes with neoplastic, malignant neoplasms of the skin, a significant violation of the quality of life of patients, disfiguring from an aesthetic point of view defects.
Causes
To date, the exact cause of the formation of the cutaneous horn has not been named. It is believed that such a powerful proliferation of the epidermis is based on a violation of cellular kinetics, which consists of several components: a sharp acceleration of mitotic cell division, accelerated migration of cells overflowing with keratin to the skin surface, acceleration of genetically programmed physiological cell death. Individually, each such component can cause adaptive changes in the skin in the form of proliferative acanthosis (an increase in the number of epidermal cells due to their excessive formation). The totality of the processes causes proliferative hyperkeratosis, an independent skin disease known as “skin horn”.
Both internal (endocrine pathology, tumors, viral infection) and external (ultraviolet, trauma) factors can provoke the development of such a process. The essence of the changes in the layers of the skin at the same time lies in the proliferation of the spiny, granular and horny layer of the epidermis, which become loose, the number of desmosomes (intercellular contacts) increases in them, which have lost contact with the tonofilaments (protein filaments of the desmosome framework and the cytoplasm of keratinocytes), “soft” zones appear, available for “pushing” their dermis. Adjacent unchanged areas of the epidermis are compensatorily embedded in the thickness of the dermis. This creates a solid foundation for horn formation. In the future, more and more new products of disturbed cellular kinetics are layered on this platform, and a primary skin horn appears.
In the case of secondary hyperkeratosis, inflammation is added, the severity of which depends on the prevalence of the cutaneous horn and its ability to transform. Exogenous-endogenous causes damage the skin (alteration), causing the release of mediators from cells into surrounding tissues – biologically active substances (serotonin, histamine), which shift the acid-base balance of the dermis to the acid side. Acidosis increases the permeability of the vessel walls, the fluid from which enters the tissues located around the base of the primary horn, triggering the process of exudation, to which the vessels react according to the feedback principle: the more fluid sweats into the dermis tissue, the narrower the vessels become, causing a violation of metabolic processes.
Ischemia is replaced by vasodilation with an increase in blood flow rate and an increase in metabolic processes in the focus of inflammation. Arteries, veins and lymphatic vessels participate in this process, when they overflow, stasis occurs (stopping blood and lymph flow), that is, the site of inflammation is separated from healthy tissues. Thus, the blood continues to flow to the platform on which the horn is formed, and there is no outflow back. The accumulating exudate contains cells that kill the pathogenic origin (lymphoid cells). It is on their activity that the spread of the further process depends, since they initiate proliferation. If the degree of cell reproduction is excessive, it becomes the provoking moment of a genetic failure in the cell division program in favor of abnormally altered cells. The patient does not experience any subjective sensations at the same time. We emphasize that this is only one of the most common theories of the formation of a cutaneous horn.
Classification
Dermatologists distinguish two types of the disease, each of which can be in the form of a single formation or multiple elements of the skin horn:
- Primary, or benign – appears on the skin spontaneously, the causes are unknown, the course is benign, there is no component of inflammation. Localization is accidental, depending on this, the primary skin horn can cause cosmetic or practical inconveniences, disrupting the quality of life. Depending on the size of the formation, the patient is monitored (malignancy cannot be excluded) or radical removal of the skin horn is proposed.
- Secondary (false), or malignant – a consequence of the transformation of the primary formation as a result of exogenous-endogenous causes with the development of an inflammatory process at the base of the horn. This is the most dangerous type of pathology, it is prone to rapid malignancy of the process, therefore, therapy should be started as soon as possible.
Symptoms
Clinically, the horny growths of the epidermis have clear boundaries, they are dense to the touch, of an indeterminate dark color, with a smooth or striated surface, and an erythematous inflammatory rim around the base. The size of the neoplasm varies, can reach ten centimeters or more. They can be cylindrical in shape, sometimes the base is many times larger in diameter than the top. Elderly people suffer from the disease more often. The cutaneous horn is mainly a single element, but it can also be multiple.
The vast majority of the appearance of the skin horn resembles the spikes of bikers in its size and cone-shaped shape. Horny hyperkeratosis is localized mainly on the skin, but it can also affect the mucous membranes, especially the red border of the lips against the background of leukoplakia (keratinization of the mucosal epithelium in smokers). The height of the cutaneous horn is a prognostic sign of malignancy of the process: small formations tend to degenerate into squamous cell skin cancer. If the cutaneous horn is a symptom of any disease, then its course and prognosis depend entirely on the primary pathology.
The cutaneous horn has two clinical features associated with the danger to the patient’s life. The first, of course, is spontaneous malignancy, and the second is a serious violation of the quality of life due to the localization of the pathological process on the limbs, face, scalp, buttock area, eyelids.
Diagnostics
Clinical manifestations of the disease are typical, however, a cutaneous horn is diagnosed with a mandatory histological examination to exclude malignancy of the process. A distinctive feature of histology is papillomatosis, pronounced hyperkeratosis, which is based on acanthosis of the granular layer of the epidermis. With the malignancy of the process, a large number of pathological mitoses are noted. Differential diagnosis is carried out with other types of keratosis, keratoderma, warts, calluses, dermatofibromas, warty nevus, psoriasis, lichen planus, angiokeratoma, tuberculosis of the skin.
Treatment
The treatment consists in the radical removal of the horny masses. The patient is operated on after consultation with a dermatologist, cosmetologist and surgeon. After removal, a small trace in the form of a scar is possible (depending on the method of treatment and the size of the neoplasm). In modern dermatology, both conventional suture surgery and cryodestruction, laser coagulation, and radiosurgery are used. The prognosis is favorable with timely diagnosis and treatment. If the cutaneous horn causes the slightest suspicion of possible malignancy, the patient is taken to the dispensary for observation in the postoperative period (relapse, metastases).