Basalioma of the skin (basal cell cancer)

Basal cell carcinoma (syn.: basalioma, basal cell epithelioma, ulcus rodens, epithelioma basocellulare) is a common skin tumor with pronounced destructive growth, a tendency to recurrence, and, as a rule, does not metastasize, which is why the term "basalioma" is more commonly used in Russian literature.

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Causes skin basaliomas

The issue of histogenesis has not been resolved, most researchers adhere to the dysontogenetic theory of origin, according to which basalioma develops from pluripotent epithelial cells. They can differentiate in various directions. Genetic factors, immune disorders, and adverse external effects (intense insolation, contact with carcinogenic substances) are important in the development of cancer. It can develop on clinically unchanged skin, as well as against the background of various skin pathologies (senile keratosis, radiodermatitis, tuberculous lupus, nevi, psoriasis, etc.).

Basalioma is a slowly growing and rarely metastasizing basal cell cancer that arises in the epidermis or hair follicles, the cells of which are similar to the basal cells of the epidermis. It is not considered cancer or a benign neoplasm, but a special kind of tumor with locally destructive growth. Sometimes, under the influence of strong carcinogens, primarily X-rays, basalioma transforms into basal cell carcinoma. The question of histogenesis has not yet been resolved. Some believe that basaliomas develop from the primary epithelial rudiment, others - from all epithelial structures of the skin, including embryonic rudiments and developmental defects.

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Risk factors

Provoking factors include insolation, UV, X-rays, burns, and arsenic intake. Therefore, basalioma is often found in people with skin types I and II and albinos who have been exposed to intense insolation for a long time. It has been established that excessive insolation in childhood can lead to the development of a tumor many years later.

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Pathogenesis

The epidermis is slightly atrophic, sometimes ulcerated, and there is a proliferation of tumor basophilic cells similar to the cells of the basal layer. Anaplasia is poorly expressed, and there are few mitoses. Basalioma rarely metastasizes, since tumor cells that enter the bloodstream are not capable of proliferation due to the lack of growth factor produced by the tumor stroma.

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Pathomorphology of basal cell carcinoma of the skin

Histologically, basal cell carcinoma is divided into undifferentiated and differentiated. The undifferentiated group includes solid, pigmented, morphea-like and superficial basaliomas, while the differentiated group includes keratotic (with piloid differentiation), cystic and adenoid (with glandular differentiation) and with sebaceous differentiation.

The international classification of WHO (1996) identifies the following morphological variants of basal cell carcinoma: superficial multicentric, codular (solid, adenoid cystic), infiltrating, non-sclerosing, sclerosing (desmoplastic, morphea-like), fibroepithelial; with appendage differentiation - follicular, eccrine, metatypical (basosquamous), keratotic. However, the morphological border of all varieties is unclear. Thus, an immature tumor may have adenoid structures and, conversely, with its organoid structure, foci of immature cells are often found. Also, there is no complete correspondence between the clinical and histological pictures. Usually there is a correspondence only in such forms as superficial, fibroepithelial, scleroderma-like and pigmented.

In all types of basaliomas, the main histological criterion is the presence of typical complexes of epithelial cells with dark-stained oval nuclei in the central part and located in a palisade along the periphery of the complexes. In appearance, these cells resemble basal epithelial cells, but differ from the latter in the absence of intercellular bridges. Their nuclei are usually monomorphic and are not subject to anaplasia. The connective tissue stroma proliferates together with the cellular component of the tumor, located in the form of bundles among the cellular cords, dividing them into lobules. The stroma is rich in glycosaminoglycans, staining metachromatically with toluidine blue. It contains many tissue basophils. Retraction gaps are often detected between the parenchyma and stroma, which many authors regard as a fixation artifact, although the likelihood of the effect of excessive secretion of hyaluronidase is not denied.

Solid basal cell carcinoma is the most common of the undifferentiated forms. Histologically, it consists of variously shaped and sized strands and cells of compactly located basaloid cells with unclear boundaries, resembling a syncytium. Such complexes of basal epithelial cells are surrounded by elongated elements on the periphery, forming a characteristic "picket fence". Cells in the center of the complexes may undergo dystrophic changes with the formation of cystic cavities. Thus, along with solid structures, cystic ones may exist, forming a solid-cystic variant. Sometimes destructive masses in the form of cellular detritus are encrusted with calcium salts.

Pigmented basal cell carcinoma is histologically characterized by diffuse pigmentation and is associated with the presence of melanin in its cells. The tumor stroma contains a large number of melanophages with a high content of melanin granules.

An increased amount of pigment is usually detected in the cystic variant, less often in the solid and superficial multicentric. Basaliomas with pronounced pigmentation contain a lot of melanin in the epithelial cells above the tumor, in its entire thickness up to the stratum corneum.

Superficial basal cell carcinoma is often multiple. Histologically, it consists of small, multiple solid complexes associated with the epidermis, as if "suspended" from it, occupying only the upper part of the dermis to the reticular layer. Lymphohistiocytic infiltrates are often found in the stroma. The multiplicity of foci indicates the multicentric genesis of this tumor. Superficial basalioma often recurs after treatment along the periphery of the scar.

Scleroderma-like basal cell carcinoma, or the "morphea" type, is characterized by abundant development of connective tissue of a scleroderma-like type, in which narrow strands of basal epithelial cells are "walled up", extending deep into the dermis down to the subcutaneous tissue. Polysad-like structures can be seen only in large strands and cells. Reactive infiltration around tumor complexes located among massive connective tissue stroma is usually scanty and more pronounced in the zone of active growth on the periphery. Further progression of destructive changes leads to the formation of small (cribriform) and larger cystic cavities. Sometimes destructive masses in the form of cellular detritus are encrusted with calcium salts.

Basal cell carcinoma with glandular differentiation, or adenoid type, is characterized by the presence, in addition to solid areas, of narrow epithelial cords consisting of several, and sometimes 1-2 rows of cells, forming tubular or alveolar structures. The peripheral epithelial cells of the latter are cubic in shape, as a result of which the polyad-like character is absent or less clearly expressed. The internal cells are larger, sometimes with a pronounced cuticle, the cavities of the tubes or alveolar structures are filled with epithelial mucin. The reaction with carcinoembryonic antigen gives positive staining of extracellular mucin on the surface of the cells lining the duct-like structures.

Basal cell carcinoma with cylindrical differentiation is characterized by the presence of keratinization foci surrounded by cells similar to spinous cells in the complexes of basal epithelial cells. In these cases, keratinization occurs without the keratohyalin stage, which resembles the keratogenic zone of the isthmus of normal hair follicles and may have a trichome-like differentiation. Sometimes immature milked follicles with initial signs of hair shaft formation are encountered. In some variants, structures resembling embryonic hair rudiments are formed, as well as epithelial cells containing glycogen, corresponding to the cells of the outer layer of the hair bulb. Sometimes there may be difficulties in differentiating with follicular basaloid hamartoma.

Basal cell carcinoma with sebaceous differentiation is rare and is characterized by the appearance of foci or individual cells typical of sebaceous glands among the basal epithelial cells. Some of them are large, signet ring-shaped, with light cytoplasm and eccentrically located nuclei. When stained with Sudan III, fat is detected in them. Lipocytes are significantly less differentiated than in a normal sebaceous gland; transitional forms are observed between them and the surrounding basal epithelial cells. This indicates that this type of cancer is histogenetically associated with the sebaceous glands.

Fibroepithelial type (syn.: Pinkus fibroepithelioma) is a rare type of basalioma, which most often occurs in the lumbosacral region, and can be combined with seborrheic keratosis and superficial basalioma. Clinically, it can look like fibropapilloma. Cases of multiple lesions have been described.

Histologically, narrow and long cords of basal epithelial cells are found in the dermis, extending from the epidermis, surrounded by hyperplastic, often edematous mucoid-altered stroma with a large number of fibroblasts. The stroma is rich in capillaries and tissue basophils. Epithelial cords anastomose with each other, consist of small dark cells with a small amount of cytoplasm and round or oval, intensely stained nuclei. Sometimes in such cords there are small cysts filled with homogeneous eosinophilic contents or horny masses.

Nevobasocellular syndrome (syn. Gordin-Goltz syndrome) is a polyorganotropic, autosomal dominant syndrome related to phakomatoses. It is based on a complex of hyper- or neoplastic changes due to embryonic developmental disorders. The cardinal symptom is the occurrence of multiple basaliomas in the early period of life, accompanied by odontotic cysts of the jaws and rib anomalies. There may be cataracts and changes in the central nervous system. It is also characterized by frequent changes in the palms and soles in the form of "depressions", in which basaloid structures are also found histologically. After the early nevoid-basaliomatous phase, after several years, usually during puberty, ulcerative and locally destructive forms appear in these areas as an indicator of the onset of the oncological phase.

Histological changes in this syndrome are practically no different from the above-mentioned varieties of basaliomas. In the area of palmar-plantar "depressions" there are defects of the stratum corneum of the epidermis with thinning of its other layers and the appearance of additional epithelial processes from small typical basaloid cells. Large basaliomas rarely develop in these places. Individual basal cell foci of a linear nature include all variants of organoid basaliomas.

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Histogenesis of basal cell carcinoma of the skin

Basalioma can develop from both epithelial cells and the epithelium of the pilosebaceous complex. On serial sections, M. Hundeiker and H. Berger (1968) showed that in 90% of cases the tumor develops from the epidermis. Histochemical examination of various types of cancer shows that glycogen and glycosaminoglycans are found in the tumor stroma in most cells, especially in adamantine and cylindromatous patterns. Glycoproteins are constantly found in the basal membranes.

Electron microscopy revealed that most cells of tumor complexes contain a standard set of organelles: small mitochondria with a dark matrix and free polyribosomes. At the contact sites, intercellular bridges are absent, but finger-shaped outgrowths and a small number of desmosome-like contacts are found. At the sites of keratinization, layers of cells with preserved intercellular bridges and a large number of tonofilaments in the cytoplasm are noted. Occasionally, zones of cells containing cellular membrane complexes are found, which can be interpreted as a manifestation of glandular differentiation. The presence of melanosomes in some cells indicates pigment differentiation. In basal epithelial cells, organelles characteristic of mature epithelial cells are absent, indicating their immaturity.

It is currently believed that this tumor develops from pluripotent germinal epithelial cells under the influence of various external stimuli. Histologically and histochemically, the connection between basal cell carcinoma and the anagen stage of hair growth has been proven, and the similarity with proliferating embryonic hair rudiments has been emphasized. R. Nolunar (1975) and M. Kumakiri (1978) believe that this tumor develops in the germinal layer of the ectoderm, where immature basal epithelial cells with differentiation potential are formed.

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Symptoms skin basaliomas

Basalioma of the skin has the appearance of a single formation, hemispherical in shape, often rounded in outline, slightly elevated above the skin level, pink or grayish-red in color with a pearlescent tint, but may not differ from normal skin. The surface of the tumor is smooth, in its center there is usually a small depression covered with a thin, loosely adhering serous scaly crust, upon removal of which erosion is usually found. The edge of the ulcerated element is thickened in a ridge, consists of small whitish nodules, usually designated as "pearls" and having diagnostic value. In this state, the tumor can exist for years, slowly increasing.

Basaliomas can be multiple. The primary multiple form, according to K.V. Daniel-Beck and A.A. Kolobjakov (1979), occurs in 10% of cases, the number of tumor foci can reach several dozen or more, which can be a manifestation of Gorlin-Goltz nevobasocellular syndrome.

All symptoms of basalioma of the skin, including Gorlin-Goltz syndrome, allow us to distinguish the following forms: nodular-ulcerative (ulcus rodens), superficial, scleroderma-like (morphea type), pigment and fibroepithelial. With multiple lesions, the above clinical types can be observed in various combinations.

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Forms

The superficial type begins with the appearance of a limited flaky pink spot. Then the spot acquires clear contours, an oval, round or irregular shape. Along the edge of the lesion, dense small shiny nodules appear, which merge with each other and form a ridge-like edge raised above the skin level. The center of the lesion slightly sinks. The color of the lesion becomes dark pink, brown. The lesions can be solitary or multiple. Among the superficial forms, self-scarring or pagetoid basalioma with an atrophy (or scarring) zone in the center and a chain of small, dense, opalescent, tumor-like elements along the periphery are distinguished. The lesions reach a significant size. Usually it has a multiple character and a persistent course. Growth is very slow. In its clinical signs, it can resemble Bowen's disease.

In the pigmented type, the color of the lesion is bluish, purple or dark brown. This type is very similar to melanoma, especially nodular, but has a denser consistency. In such cases, dermatoscopic examination can be of significant help.

The tumor type is characterized by the appearance of a nodule, which gradually increases in size, reaching 1.5-3 cm or more in diameter, acquires a rounded appearance, a congestive pink color. The surface of the tumor is smooth with pronounced telangiectasias, sometimes covered with grayish scales. Sometimes its central part ulcerates and becomes covered with dense crusts. Rarely, the tumor protrudes above the skin level and has a stalk (fibroepithelial type). Depending on the size, small- and large-nodular forms are distinguished.

The ulcerative type occurs as a primary variant or as a result of ulceration of the superficial or tumor form of the neoplasm. A characteristic feature of the ulcerative form is a funnel-shaped ulceration, which has a massive infiltrate (tumor infiltration) fused with the underlying tissues with unclear boundaries. The size of the infiltrate is significantly larger than the ulcer itself (ulcus rodens). There is a tendency to deep ulceration and destruction of underlying tissues. Sometimes the ulcerative form is accompanied by papillomatous, warty growths.

The scleroderma-like, or cicatricial-atrophic, type is a small, clearly delineated lesion with a compaction at the base, almost not rising above the skin level, yellowish-whitish in color. Atrophic changes and dyschromia may be detected in the center. Periodically, erosive foci of various sizes may appear along the periphery of the element, covered with an easily detachable crust, which is very important for cytological diagnostics.

Pinkus fibroepithelial tumor is classified as a type of basalioma, although its course is more favorable. Clinically, it appears as a skin-colored nodule or plaque, of a dense elastic consistency, and is practically not subject to erosion.

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Differential diagnosis

Basalioma must be distinguished from keratoacanthoma, spinocellular epithelioma, chancroid pyoderma, Bowen's disease, seborrheic keratosis, lichen sclerosus, malignant melanoma, and cutaneous lymphocytoma.

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Treatment skin basaliomas

Treatment of basal cell carcinoma is surgical removal of the tumor within healthy skin. Cryodestruction is often used in practice. Radiation therapy is used in cases where surgery results in a cosmetic defect.

Prospidin and colchamine ointments are used externally.