Basal cell carcinoma

Introduction to basal cell carcinoma Basal cell carcinoma (BCC) is one of the most common types of skin cancer, also known as basal cell epithelioma (basalcellepithelioma), basal cell tumor, erosive ulcer, etc., which is derived from the epithelial cells of the epidermal basal cells or the outer root sheath of the hair follicle. Low-grade malignant tumors. basic knowledge The proportion of sickness: 0.01% Susceptible people: no specific population Mode of infection: non-infectious Complications: Eczema

Basal cell carcinoma etiology

(1) Causes of the disease

Basal cell carcinoma originates from the skin or accessory, especially the basal cells of the hair follicle. It is a low-grade malignant tumor. The accessory tumor is developed from the primitive epithelial germ cells. This disease is the most differentiated malignant accessory tumor, which is more common in the face color. Light exposure of people and heads, indicating that long-term sun exposure is closely related to the onset of the disease, such as arsenic, high-dose X-ray, coal tar derivatives, burns, scars and chronic inflammation (sinus, calf ulcer, Sweat gland inflammation, etc.) are risk factors for the onset of this disease. Patients with weakened immunity may increase the risk of basal cell carcinoma and the immune system of patients due to impaired cellular immunity and increased susceptibility to tumorigenic virus. The pathogenesis and prognosis of this tumor, environmental carcinogens such as oncogenic viruses can be enhanced by the accompanying immunosuppression, and basal cell carcinoma in organ transplant patients is more than 10 times higher than normal, and found in these lesions. Herpesvirus-like DNA sequences, some histological types are more common in immunosuppressed patients such as scleroderma-like basal cell carcinoma, in immunosuppression It is more common than nodular ulcerative basal cell carcinoma. Superficial basal cell carcinoma is more common in patients with diabetes and/or chronic renal failure and HIV infection. Some genetic diseases such as albinism and pigmented dry skin disease, Rasmussen syndrome, Rombo syndrome, Bazax syndrome and Darier disease increase the incidence of basal cell carcinoma.

The occurrence of this disease is related to the skin damage at the exposed part due to external factors:

1. Long-term exposure to sunlight This disease occurs in the scalp, and exposed parts such as the face are more common in outdoor workers. It is proof that the ultraviolet rays in the sun invade the human body, causing DNA damage in the cells and damage to the skin. According to foreign statistics, white people are more susceptible to skin cancer than people of color. This is related to the fact that melanin in the skin can protect the skin from UV damage. The ozone layer on the earth becomes thinner, forming an ozone hole, causing excessive ultraviolet radiation, which can cause The increase in skin cancer patients.

2. Excessive radiation exposure on the basis of chronic dermatitis, exposure to excessive radiation can induce skin cancer, Anderson (1951) and Traenkle (1964) found that the disease often occurs on the basis of chronic radiation dermatitis, they report radiation Workers develop primary cancer in radiation dermatitis due to long-term small amount of X-ray exposure. Sarkany (1968) found that patients with lichen planus and spondylitis develop multiple basal cell carcinoma and premalignant fibroepithelial neoplasia on the dorsal skin due to X-rays. The incubation period is 11 to 28 years, and the dose for irradiation is 154.8 to 2 289.8 mC/kg (600 to 8875 Rad).

3. Chemicals stimulate long-term exposure to inorganic arsenic (such as compound potassium arsenite solution) or drink arsenic-containing drinking water or food, which is susceptible to basal cell carcinoma. According to Shu et al., 1963, Taiwan basal cells in areas with high arsenic content The incidence of cancer is about 11%. Skin cancer caused by arsenic occurs in the non-exposed areas of the body and in the palm of the hand, and is usually multiple.

4. Physical factors Skin cancer can also appear on scars after unstable atrophic burns, chronic ulcers or sinus, chronic granuloma, chronic osteomyelitis, epithelioid hyperplasia, lupus vulgaris, lichen planus, leprosy, etc. More and more, after more than 10 years or decades, cancer may occur, occasionally simple trauma such as acne.

5. Other factors Some hamartomas such as sebaceous adenoma, papillary sweat duct cystadenoma and premalignant fibroepithelial neoplasia are prone to basal cell carcinoma, and even epithelium above the skin fibroid can also develop basal cell carcinoma.

(two) pathogenesis

Basal cell carcinoma originates from the pluripotent basal cells of the epidermis or skin appendage. It can differentiate into multiple directions. The cancer cells resemble basal cells, which are oval or fusiform, with deep nucleus staining, few cytoplasm, and unclear cell boundaries. The intercellular bridge is often not obvious. There is a basal zone positive for PAS staining between the tumor parenchyma and interstitium. The fibroblasts in the interstitial connective tissue proliferate, and there are many immature fibroblasts. The interstitial is the most acidic. Mucopolysaccharide is mucoid and has metachromatic effect. Because the specimen is fixed and dehydrated, the interstitial mucin shrinks and partially or completely separates from the tumor parenchyma. Although this phenomenon is artificial, it can assist with other tumors. Such as squamous cell carcinoma.

1. There are four types of undifferentiated:

(1) solid basal cell carcinoma: also known as primordial carcinoma, clinically common, there are multiple sizes in the dermis, irregular cord-like or mass-like cancer cell mass, often partially connected with the epidermis, even Or connected to the outer root sheath, the cancer cells at the edge of the cancer cell cluster are arranged in a grid; the internal arrangement is disordered.

(2) Pigmented basal cell carcinoma: This basal cell carcinoma is rich in melanin, which is found in melanocytes and mesenchymal melanocytes in cancer cells.

(3) superficial basal cell carcinoma: often multiple, connected to the epidermis base layer, irregularly elongated into the superficial dermis, like the original epithelial bud, the interstitial is often not obvious, and later can develop into invasive basal cell carcinoma.

(4) Sclerosing basal cell carcinoma: The interstitial fibrous tissue is most proliferating and dense, and the cancer cell mass is extruded into a thin strip, and the latter is usually only a single layer of cells.

2. There are three types of differentiation:

(1) Keratinizing basal cell carcinoma: In addition to undifferentiated cancer cells, keratinocytes and keratinous cysts can be seen. Lever believes that keratinocytes tend to form hair shafts, and keratinocytes can be arranged in bundles or The vortex, or around the keratinocyte, may be the initial hair keratinocytes, which Ackerman believes is not a basal cell carcinoma that differentiates into hair follicles.

(2) Cystic basal cell carcinoma: cystic cavities appear in the center of cancer cell clusters. The formation pathway is: large pieces of cancer cells are necrotic; cancer cells disintegrate after differentiation into sebaceous gland cells, and some cancer cells around the cystic cavity are vacuolated or Foam-like (equivalent to sebaceous gland cells); interstitial necrosis that protrudes into the tumor parenchyma.

(3) Adenoid basal cell carcinoma: The tumor is tube-like or adenoid-like, and the cancer cells are arranged in a line that is consistent with each other. The connective tissue between the strips is island-like connective tissue. The lumen of the tumor is seen in the cavity. Shape, like glandular epithelial cells, but no secretory activity, small sweat gland epithelioma (eccrine epithelioma) is a kind of adenoid basal cell carcinoma, which differentiates into the duct, resembling a sweat duct tumor, but the tumor is bulky and deep Invasion.

Basal cell carcinoma prevention

Early attention and discovery of some precancerous lesions, timely treatment, which has great significance in prevention.

Basal cell carcinoma complications Complications eczema

Basal cell carcinoma intracranial invasion and lung metastasis, basal cell carcinoma develops slowly, can be in a relatively stable state within 20 to 30 years, if not treated, often ulceration, slow to deep tissue invasion, especially in the face, can destroy the nose Cartilage or bone at the ear, eyelids, and maxillary sinus, causing hemorrhage or intracranial invasion, but less regional lymph node metastasis, few hematogenous metastases, and most of the metastases are lungs.

Basal cell cancer symptoms Common symptoms Hair growth, slow growth, hard spot, scarring, mental retardation, jaw cyst, erythema scales

Basal cell carcinoma occurs mostly after 30 years of age, 70 years old is the peak, occurs in the head and face, especially the nose, eyelids and cheeks are the most common, the basic damage is needle to mung bean large, hemispherical, waxy or translucent nodules .

85% of patients occurred in the exposed area of the head and neck. The palmar and mucous membranes were rare. The lesions were usually single, but there were several or even most cases. The early stage of basal cell carcinoma was a slight uplift of the local skin, pale yellow or pink nodules. Section, only needle or mung bean size, translucent nodules, hard, epidermis, with telangiectasia, but no pain or tenderness, lesions located in the deep epidermis, the surface of the skin is slightly sunken, losing the luster of normal skin and Texture, after several months or years, the appearance of scaly desquamation, after repeated crusting, desquamation, performance ulceration, oozing, when the lesion continues to increase, the formation of superficial ulcers in the middle, the edge of the uneven, Like eclipse, the surface of basal cell carcinoma is variously formed. According to the morphology seen by the naked eye, it can be roughly divided into the following types:

1. Nodulo-ulcerative basal cell carcinoma (Nodulo-ulcerative basal cell carcinoma) is the most common, accounting for 50% to 54% of basal cell carcinoma. The damage is single, which occurs in the face, especially the cheeks, paranasal sulcus, forehead. Wait.

(1) Nodular type: damage is prominent skin, from needle size to mung bean size, small waxy nodules from the beginning, slowly increasing, non-inflammatory light yellow brown or light gray white, waxy or half Transparent (such as pearl-like) nodules, hard, surface dermis disappeared, the epidermis is thin with superficial telangiectasia, the epidermis is generally not broken (Figure 1), slightly traumatic or bleeding.

(2) Ulcerative type is the most common type in the clinic, especially in the face, which is characterized by local minor damage. After the skin collapses, it will last for a long time, or there will be small nodules of the skin, then gradually grow and grow. Slow, central depression, surface erosion or ulceration, and then collapsed, the bottom of the ulcer is granular or granulated, cauliflower or sputum growth, covered with serous secretions; the edge of the ulcer continues to expand, visible mostly light gray A small nodule with a waxy or pearl-like appearance, surrounded by uneven, rounded edges that are rolled up in a pearl shape, called a rodent ulcer, which is a typical clinical form of this cancer. Sinking, shaped like a crater, the central mouth of the ulcer can heal and the scar forms, but the edge can continue to expand, sometimes the center breaks and breaks into the surrounding or deep, shaped like a rat, so it is also called "claw ulcer" ". Occasionally, the lesion is invasively enlarged, growing deep, destroying the eyes, nose, and even penetrating the skull, invading the dura mater, causing death.

2. Pigmented basal cell carcinoma is a pigmentation in all types, accounting for 6% of basal cell carcinoma. It differs from nodular ulcer type only in that the lesion is brown or dark black, sometimes It is easily misdiagnosed as malignant melanoma. The clinical features are similar to those of nodular type. It is accompanied by different degrees of pigmentation, white ash to dark black, but uneven, the edge part is often deep, and the central part is dotted or reticular.

3. Morphologically basal cell carcinoma (morphealike basa cell carcinoma), also known as localized morphea-like basal cell carcinoma, rare, accounting for only 2% of basal cell carcinoma, Caro statistics of 2 116 cases of skin cancer Only 34 cases of this type, Botvinnick (1967) statistics of 3000 cases of this type of cancer accounted for 0.6%, mostly occurred in young people, also seen in children, often single, good for the face, forehead, ankle, Nasal and eyelids, especially in the cheeks, neck or chest, can occur as a flat or lightly depressed yellow-white waxy to sclerosing infiltrating plaque, irregular or Portuguese, the size is from a few millimeters To occupy the entire forehead, gray to pale yellow, smooth surface, can see telangiectasia, hard to touch, similar to localized scleroderma, lack of rolled up pearly edges, no ulcers and crusting, often no edge Clear, skin lesions develop slowly.

4. Superficial basal cell carcinoma (superficial basal cell carcinoma) is rare, more common in men, early onset, very few heads, which account for 9% to 11% of basal cell carcinoma, often occurs in the trunk, especially It is the back and chest, also seen on the face and limbs. The lesion is one or several mild invasive erythema scaly patches. The surface is thin and has a slightly raised linear border. The superficial ulcer often appears in the center. The skin can be changed by eczema or psoriasis, slowly increasing to the surrounding area, and the boundary is clear. It is often surrounded by thin-lined pearl-like edges. The surface of the lesion is visible with small superficial ulcers, and the smooth and atrophy remains. Sexual scars.

5. Fibroepithelioma type basal cell carcinoma (fibroepithelioma type basal cell carcinoma) is characterized by one or several high nodules, slightly pedicled, medium hardness, smooth surface, mild redness, clinically similar fibers Tumor, occurs in the lower back, rare ulcer formation, clinically similar to fibroids.

6. The flat scar type (epithelioma planum cic-artrisans) is quite rare, often occurs on the face, the damage is superficial nodular plaque, and the growth is slow. This type is characterized by the fact that basal cell carcinoma slowly spreads around. At the center, the tumor cells gradually disappear and form scars, just as the forest fire spreads around, but the center is self-extinguishing. Therefore, it is also called wildfire type, and its extended edge is highly aggressive.

7. Nevoid basal cell carcinoma syndrome, also known as basal cell nevous syndrome, is an autosomal dominant hereditary disease with low penetrance, protruding skin, and hard , smooth nodular mass, can be normal skin color or mild pigmentation, in some cases, the mass gradually enlarges, eventually forming ulcers, most with upper and lower jaw cysts, rib deformities and mental retardation, childhood, At the latest, there are hundreds of thousands of small skin nodules in puberty. In the "sputum-like" period, the number and size of nodules gradually increase, irregularly distributed in the face and body. In adulthood, many basal cell carcinomas often collapse. In late life, the disease sometimes progresses to the "tumor" stage. At this time, some basal cell carcinomas, especially facial lesions, become invasive, destructive, and defective. Occasionally, even if they invade the eyelids, they may invade the brain and die, and may also metastasize to the lungs. In half of adult patients, there are many small depressions with a diameter of 1 to 3 mm in the palmar sac, which often occur in 11 to 20 years old, and are basal cell carcinoma of the stagnation.

In addition to skin lesions, almost all patients presented with multiple bone and central nervous system abnormalities, such as jaw odontogenic cysts, rib abnormalities, scoliosis, mental retardation and cerebral calcification, there are several reports, see also Cerebellar neuroblastoma, maxillary or jaw fibrosarcoma, ameloblastoma in the jaw cyst.

8. Cystic basal cell carcinoma (cystic basal cell carcinoma) is rare, which is caused by degeneration of the central part of the cancer, forming a single atrial cyst, usually blue-gray.

9. The linear basal cell Nevus is extremely rare. It is often found at birth. It has a wide rash and is unilateral linear or banded rash. The lesion is composed of dense basal cell carcinoma nodules. There are scattered areas of acne and pattern atrophy, and the damage does not increase with age.

10. The Bazex syndrome (Bazex syndrome) was first reported by Bazex et al in 1966. The disease is dominantly hereditary. The main features are the atrophy of the hair follicle skin, the expansion of the hair follicles in the extremities, and the ice-cutting marks. Multiple small basal cell carcinomas that occur in children, youth, or juvenile faces, in addition to limited local sweatlessness and/or systemic hypohidrosis and congenital head and other areas of hair sparse.

Basal cell carcinoma examination

1. Histopathological examination

It can be seen that the cancer cells are fusiform, with large nuclear staining, no intercellular bridge, and invasive growth. Specimen collection can be scraped, removed, acupuncture and resection methods.

The tumor cell mass is located in the dermis and is connected to the epidermis. The tumor cells resemble the basal cells of the epidermis, but the nucleus is large, ovate or elongated, the cytoplasm is relatively small, the cell boundary is unclear, there is no intercellular bridge between cells, and the surrounding cells are arranged in a grid. The boundary is clear, the nuclear size, morphology and staining of the tumor cells are quite consistent, without any change, the connective tissue around the tumor mass is proliferated, and the tumor clusters are arranged in parallel bundles, among which there are many naive fibroblasts, and mucin degeneration can be seen due to Mucin shrinks during the fixation and dehydration of the specimen, and thus there is a crack around the tumor. Although this is an artificial phenomenon, it is a typical manifestation of the disease and helps to distinguish it from other tumors.

Histologically, basal cell carcinoma can be divided into two types, namely, undifferentiated and differentiated. The differentiation is mild to the skin appendage, ie hair, sebaceous gland and apocrine gland or small sweat gland, but there is no obvious boundary, because many undifferentiated It can also show some differentiation in some areas, while most of the differentiation types lack differentiation in some areas, combined with clinical lesion morphology, nodular ulceration can show differentiation or undifferentiation, while pigmented, superficial and fibroepithelial neoplasia Sexuality, often showing very poorly differentiated or undifferentiated, combined with clinical and histological classification, so-called nodular ulcerative basal cell carcinoma and sputum-like basal cell carcinoma syndrome, linear unilateral basal cell nevus and Bazex syndrome can show differentiation Or not differentiated, and the other four basal cell carcinomas, namely, chromophobic, scleroderma-like, superficial and fibroepithelial, often show little or no differentiation, and their histological classification is as follows:

(1) Solid basal cell carcinoma: also known as basal basal cell carcinoma, which is characterized by different sizes of tumors embedded in the dermis, and more than 90% of basal cell carcinomas can be seen as tumor cells. The group is connected to the surface epidermis, and occasionally the tumor group is in contact with the outer root sheath. The surrounding layer of the tumor group is often arranged in a grid shape, and the nucleus has no certain way.

(2) Keratotic basal cell carcinoma: also known as hair type, except for undifferentiated cells, with keratinocytes and horn cysts, keratinocytes with long nuclei and mild eosinophils Cytoplasm, unlike deep basophilic cytoplasm of undifferentiated cells, keratinized cells are arranged in bundles, concentric vortex or around horn cysts. These cells may be early hair keratinocytes, some resembling normal hair keratinogenesis. The nucleated cells in the cell area, the horn cysts composed of sufficient keratinocytes represent the formation of the hair shaft, just like the keratinization of the hair shaft, the formation of horn cysts in the middle stage of the granule-free cells, keratinizing basal cell carcinoma and hair. Epithelial tumors have horn cysts, so sometimes the two are difficult to distinguish, it is necessary to use clinical data to determine, in addition, can not be confused with the horn cells of squamous cell carcinoma.

(3) cystic basal cell carcinoma: one or several cystic cavities in the lobule of the tumor, mostly due to the progressive necrosis of the central tumor cells of the tumor island. In rare cases, the central cells of the tumor island are disintegrating. The former manifests itself as a vacuole, suggesting differentiation into the sebaceous glands.

(4) adenoid basal cell carcinoma: a tubular adenoid structure in which cells are arranged to interweave and radially surround the connective tissue island, making the tumor lace-like.

(5) Pigmented basal cell carcinoma: silver staining, there are scattered melanocytes in the tumor cell mass. The cytoplasm of these melanocytes and the dendrites have many melanin particles, and the tumor cells often contain A very small amount of melanin, but there are many melanocytes in the connective tissue interstitial around the tumor.

(6) Morpho-like basal cell carcinoma: This type of connective tissue participates much more than other types of basal cell carcinoma. Numerous arrays of growth-like cordoma cells are embedded in dense fibrous interstitial Most of the cells are stenotic, often with only one layer of thick cells, similar to those seen in breast cancer with metastatic breast cancer.

(7) superficial basal cell carcinoma: This type of basal cell carcinoma is characterized by a bud-like irregular hyperplasia of the tumor tissue attached to the epidermis, and the cells surrounding the tumor tissue are often grid-like. In most cases, the tumor tissue rarely penetrates into the dermis, and the covered epidermis often shrinks. Fibroblasts are often quite numerous. They are arranged around the hyperplasia of the tumor cells, and there is a mild to moderate amount of non-specific chronic inflammatory infiltration in the upper part of the dermis.

(8) epithelioma type basal cell carcinoma: This type of tumor cells are arranged in a slender and branched anastomosis, embedded in the fibrous interstitial, and most of the cords are connected to the epidermis. Deep-stained cells lined up in the shape of a grid around the epithelial cord, the tumor is shallow and the lower boundary is distinct.

2. Immunohistochemistry

Basal cell carcinoma cytokeratin staining was positive, and alpha-2 and 1 intergrin staining were also positive, but intercellular adhesion molecule 1 (1CAM-1), leukocyte functional antigen la (LFA-la) and vascular cell adhesion molecule 1 ( VCAM-1) is negative, and sometimes the tumor cells are positive for HLA-DR antigen, and most tumor cells are positive for P53 protein expression.

X-ray, CT and MRI examinations are helpful in estimating the extent and level of invasion of the cancer.

Diagnosis of basal cell carcinoma

Diagnostic criteria

According to the characteristics of clinical manifestations and pathological examination, immunohistochemical characteristics are not difficult to diagnose. When basal cell carcinoma has typical characteristics, such as nodules more than a few millimeters, it is easy to identify, and diagnosis can be made according to clinical manifestations.

Medical history

Whether there is radiation, inorganic arsenic and other contact history, chronic skin damage and long-term outdoor work.

Differential diagnosis

Should be differentiated from squamous cell carcinoma, Bowen's disease, Paget's disease, solar keratosis, seborrheic keratosis.

1. The initial stage of nodular type should be differentiated from infectious soft palate and senile sebaceous gland hyperplasia. The latter is often filled with keratin-like dentate depression.

2. Ulcer type should be differentiated from ulcerated squamous cell carcinoma.

3. Pigment type should be differentiated from malignant melanoma, such as marginal basal cell carcinoma, telangiectasia, brown color, no pigmentation around, basal cell carcinoma with early pigmentation and contagious soft palate, senile cutaneous gland hyperplasia It is difficult to distinguish, the latter can be seen in the center of the damage is filled with keratin dot-like depression.

4. Sclerosing basal cell carcinoma is similar to localized scleroderma, but the margin of the former is often not very clear. The final diagnosis is mainly by histopathological examination.

5. Superficial type is easy to be confused with eczema, psoriasis, common warts, keratoacanthoma, squamous cell carcinoma or infectious soft palate, but if you pay attention to its linear edge, you can identify it when there is obvious knot on the surface of basal cell carcinoma. When sputum or scaly, it should be differentiated from common sputum, keratoacanthoma and squamous cell carcinoma. Superficial basal cell carcinoma is similar to eczema, lichen planus and psoriasis, but it should be noted that the linear edge is unclear. The localized scleroderma is differentiated, and the scales of superficial basal cell carcinoma are easily peeled off, but it is often determined by pathological examination.

6. Fibrous epithelial tumor type should be differentiated from fibroids.

7. Cystic basal cell carcinoma should be differentiated from other skin cysts. The rate of misdiagnosis is extremely high only by visual observation. It must be confirmed by histopathological examination.

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