Atlas of pathophysiology, 2 Edition

Part II - Disorders

Skin Disorders

Skin cancers

Basal cell carcinoma

Basal cell carcinoma, also known as basal cell epithelioma, is a slow-growing, destructive skin tumor. The most common form of skin cancer, it rarely metastasizes.

Causes

·   Prolonged sun exposure (most common)

·   Extensive sunburns or sun exposure in childhood

·   Arsenic, radiation, burns, immunosuppression

·   Previous X-ray therapy for acne

Pathophysiology

The pathogenesis is uncertain, but it's thought to originate when undifferentiated basal cells become carcinomatous instead of differentiating into sweat glands, sebum, and hair.

Signs and symptoms

Noduloulcerative lesions

·   Usually occur on the face, particularly the forehead, eyelid margins, nasolabial folds

·   Lesions small, smooth, pinkish, and translucent papules with telangiectatic vessels crossing the surface; occasionally pigmented

·   When lesions enlarge, centers possibly depressed and borders firm and elevated

·   Eventual local invasion and ulceration, or “rodent ulcers” (these rarely metastasize but can spread to vital areas and become infected or cause massive hemorrhage)

Superficial basal cell carcinoma

·   Commonly multiple; usually occur on the chest and back

·   Oval or irregularly shaped, lightly pigmented plaques, with sharply defined, slightly elevated threadlike borders:

§  superficial erosion scaly in appearance; small, atrophic areas in center resembling psoriasis or eczema

§  usually chronic and unlikely to invade other areas

Sclerosing basal cell carcinoma (morphea-like carcinoma)

·   Waxy, sclerotic, yellow to white plaques; no distinct borders

·   Occur on the head and neck

Diagnostic test results

Incisional or excisional biopsy and histologic study determine the tumor type.

Treatment

·   Surgical excision

·   Curettage and electrodesiccation

·   Topical 5-fluorouracil, imiquimod

·   Microscopically controlled surgical excision (Mohs' surgery)

·   Irradiation

·   Cryotherapy with liquid nitrogen

·   Chemosurgery: for persistent or recurrent lesions

Squamous cell carcinoma

Squamous cell carcinoma of the skin is an invasive tumor with metastatic potential that arises from the keratinizing epidermal cells.

Causes

·   Overexposure to the sun's ultraviolet rays

·   Premalignant lesions, such as actinic keratosis or leukoplakia

·   X-ray therapy

·   Ingested herbicides, medications, or waxes containing arsenic

·   Chronic skin irritation and inflammation

·   Local carcinogens, such as tar and oil

·   Hereditary diseases, such as xeroderma pigmentosum and albinism

Signs and symptoms

·   Induration and inflammation of a preexisting lesion

·   Slowly growing nodule on a firm, indurated base; eventual ulceration and invasion of underlying tissues

·   Metastasis to regional lymph nodes: characteristic systemic symptoms of pain, malaise, fatigue, weakness, anorexia

Diagnostic test results

Excisional biopsy determines the tumor type.

Treatment

·   Surgical excision

·   Electrodesiccation and curettage

·   Radiation therapy

·   Chemosurgery

Malignant melanoma

A malignant neoplasm that arises from melanocytes, malignant melanoma is relatively rare and accounts for only 1% to 2% of all malignancies. However, the incidence is rapidly increasing, by 300% in the past 40 years. The four types of melanomas are superficial spreadingnodular malignantlentigo maligna, and acral lentiginous.

Melanoma spreads through the lymphatic and vascular systems and metastasizes to the regional lymph nodes, skin, liver, lungs, and central nervous system. Its course is unpredictable, and recurrence and metastases may not appear for more than 5 years after resection of the primary lesion. The prognosis varies with tumor thickness. Generally, superficial lesions are curable, whereas deeper lesions tend to metastasize.

Causes

·   Excessive exposure to sunlight

Contributing factors

·   Skin type: most common in persons with blonde or red hair, fair skin, and blue eyes; who are prone to sunburn; and who are of Celtic or Scandinavian ancestry; rare among people of African ancestry

·   Hormonal factors: growth possibly exacerbated by pregnancy

·   Family history: slightly more common within families

·   Past history of melanoma

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SKIN RESPONSE TO ULTRAVIOLET RADIATION

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Signs and symptoms

Melanoma (if any skin lesion or nevus)

·   Enlarges, becomes inflamed or sore, itches, ulcerates, bleeds, undergoes textural changes

·   Changes color or shows signs of surrounding pigment regression (halo nevus or vitiligo)

Superficial spreading melanoma

·   Arises on an area of chronic irritation

·   In women, most common between the knees and ankles; in Blacks and Asians, on the toe webs and soles—lightly pigmented areas subject to trauma

·   Red, white, and blue color over a brown or black background and an irregular, notched margin

·   Irregular surface with small elevated tumor nodules that may ulcerate and bleed

Nodular melanoma

·   Usually a polypoidal nodule, with uniformly dark or grayish coloration—resembles a blackberry

·   Occasionally, flesh-colored, with flecks of pigment around its base; possibly inflamed

Lentigo maligna melanoma

·   Resembles a large (3- to 6-cm) flat freckle of tan, brown, black, whitish, or slate color

·   Irregularly scattered black nodules on the surface

·   Develops slowly, usually over many years, and eventually may ulcerate

·   Commonly develops under fingernail, on face, or on back of hand

Clinical Tip

Remember the ABCDEs of malignant melanoma when examining skin lesions:

A. ASYMMETRICAL lesion

B. BORDER is irregular

C. COLORS of lesion are multiple types

D.DIAMETER of the lesion is > 0.5 cm

E. ELEVATED or ENLARGING lesion

Diagnostic test results

·   Excisional biopsy and full-depth punch biopsy with histologic examination shows tumor thickness and disease stage.

·   Complete blood count with differential reveals anemia.

·   Other blood tests show elevated erythrocyte sedimentation rate, abnormal platelet count, and abnormal liver function tests.

·   Chest X-ray assists with staging.

·   Computed tomography scan of abdomen, pelvis, neck, brain, and bone detects metastasis.

Treatment

·   Surgical resection to remove the tumor

·   Regional lymphadenectomy

·   Adjuvant chemotherapy and biotherapy

·   Radiation therapy

Clinical Tip

Regardless of the treatment method, melanomas require close long-term follow-up to detect metastasis and recurrences. Statistics show that 13% of recurrences develop more than 5 years after primary surgery.

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TYPES OF SKIN CANCER

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ABCDEs OF MALIGNANT MELANOMA

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