Integumentary
Skin Cancer
Overview of Skin Cancer
Skin cancer is the most common form of cancer in the U.S.
Approximately 5.4 million cases per year are diagnosed.
Risk Factors for Skin Cancer:
Fair skin
History of sunburns and suntanning activities
Living at or near the equator or at high altitudes
Personal or family history of skin cancer
Occupation or activities that involve prolonged sun exposure
Types of Skin Cancer
1. Basal Cell Carcinoma
Definition
Most common type of skin cancer.
Least deadly form of skin cancer.
Demographics
Typically occurs in middle-aged to older adults.
Commonly occurs in areas exposed to sunlight such as the head and neck.
Characteristics
Related to sun exposure, skin type, x-ray radiation, scars, and certain types of nevi (moles).
Change occurs in basal cells: no maturation or normal keratinization, continuing division, and formation of an enlarging mass.
Growth Rate and Treatment
It is a slow-growing tumor that invades local tissue but metastasis is rare.
Has a 90% cure rate with primary lesions.
Types of Basal Cell Carcinoma:
Nodular and Ulcerative:
Small, slowly enlarging papule with semitranslucent or "pearly" borders.
Telangiectasia (small visible blood vessels) may be present.
Center may erode, ulcerate, or depress; normal skin markings are lost.
Superficial:
Red, pearly, sharply defined, and barely elevated plaques.
Treatment Options:
Surgical excision, electrodessication and curettage, cryosurgery, radiation therapy, laser therapy, photodynamic therapy.
Medications
Vismodegib (Erivedge), sonidegib (Odomzo) for metastatic or recurrent locally invasive lesions.
Fluorouracil and imiquimod are used for superficial lesions.
2. Squamous Cell Carcinoma
Definition
Cancer of the keratinizing epidermal cells with potential to metastasize.
Risk Factors
Sun exposure & immunosuppression.
Occurence
Often arises from actinic keratosis (AK) or other lesions.
Characteristics
Most common on sun-exposed areas like the face and hands.
High cure rate with early detection and treatment.
Subtypes:
Superficial:
Thin, scaly, red plaque without invasion into the dermis.
Early Stage:
Firm nodules with indistinct borders, scaling, and possible ulceration.
Late Stage:
Lesion covered with scale or horn from keratinization, often associated with ulceration.
Treatment Options:
Surgical excision, cryosurgery, radiation therapy, electrosurgery, laser therapy, photodynamic therapy.
Fluorouracil and imiquimod for noninvasive SCC.
Immunotherapy for metastatic lesions.
3. Melanoma
Definition
A neoplastic growth originating from melanocytes, causes most skin cancer deaths.
More than 107,000 cases per year, leading to approximately 8,000 deaths annually.
Genetic Factors and Subtypes:
There are four subtypes:
Superficial spreading melanoma
Nodular melanoma
Lentigo maligna melanoma
Acral lentiginous melanoma
Stages of Melanoma:
Stage 0:
Melanoma confined to epidermus.
Stage I:
Localized disease, very thin lesions.
Stage II:
Localized disease, thicker than Stage I.
Stage III:
Spread to lymph nodes.
Stage IV:
Metastatic disease, spread to other organs.
Characteristics of Melanoma:
Irregular color, surface, and border.
Variegated color (red, white, blue, black, gray, brown).
Lesion is often <1 cm in size and can be flat or elevated, eroded, or ulcerated.
Most common sites for males are the back, then chest; for females, the legs, then the back.
Treatment Options:
Surgical excision with possible sentinel lymph node evaluation.
Adjuvant therapy post-surgery if lesion >1.5 mm in depth.
Key therapies include immunotherapy (cytokines, PD-1 inhibitors, CTLA-4 inhibitors) and targeted therapies (BRAF and MEK inhibitors).
Knowledge Check (Questions for Review)
Which statements describe malignant melanoma?
a. Related to chemical exposure
b. Neoplastic growth of melanocytes
c. Skin cancer with highest mortality rate
d. Irregular color and asymmetric shape
e. Frequently occurs on previously damaged skin
What skin condition has hyperkeratotic scaly lesions, is a precursor of squamous cell carcinoma, and may be treated with topical fluorouracil (5-FU)?
a. Actinic keratosis
b. Basal cell carcinoma
c. Malignant melanoma
d. Squamous cell carcinoma
What characteristic is commonly seen with dysplastic nevus syndrome?
a. Associated with sun exposure
b. Precursor of squamous cell carcinoma
c. Slow-growing tumor with rare metastasis
d. Lesion has irregular color and asymmetric shape
What is the most common type of skin cancer that has pearly borders?
a. Actinic keratosis
b. Basal cell carcinoma
c. Malignant melanoma
d. Squamous cell carcinoma
For which patient is it most important to instruct about the need to use sunscreen?
a. A 32-year-old patient with pneumonia who has a new prescription for doxycycline
b. A fair-skinned 55-year-old patient with psoriasis who works outside for 8 hours daily
c. A dark-skinned 62-year-old patient who has had keloids injected with hydrocortisone
d. A 78-year-old patient with a red pruritic rash
Photosensitivity from Medications
Categories of Drugs That May Cause Photosensitivity include:
Antidepressants (e.g., fluoxetine, paroxetine, venlafaxine)
Antidysrhythmics (e.g., amiodarone, quinidine)
Antihistamines (e.g., cetirizine, chlorpheniramine, diphenhydramine)
Antimicrobials (e.g., tetracycline, azithromycin, ciprofloxacin)
Antifungals (e.g., griseofulvin, ketoconazole)
Antipsychotics (e.g., chlorpromazine, haloperidol)
Cholesterol-lowering agents (e.g., atorvastatin, simvastatin)
Diuretics (e.g., furosemide, thiazides)
Hypoglycemics (e.g., glipizide, glyburide)
Nonsteroidal anti-inflammatory drugs (e.g., diclofenac, ibuprofen)
Common Skin Infections
Bacterial Infections
Primary Infections:
Occur due to break in the skin.
Secondary Infections:
Occur on already damaged skin.
Main Bacteria:
Staphylococcus aureus and group A β-hemolytic streptococci.
Fungal Infections
Candidiasis
Caused by Candida albicans, known as moniliasis.
50% of adults are symptom-free carriers.
Immunosuppression can lead to pathogenic yeast.
Common Clinical Manifestations:
Mouth: white, cheesy plaque resembling milk curds.
Skin: diffuse, papular, red rash with pinpoint lesions around the edges.
Common Fungal Infections:
Tinea Corporis: Various dermatophytes (ringworm).
Tinea Cruris: Jock itch from dermatophytes.
Tinea Pedis: Athlete's foot.
Viral Infections
Herpes Simplex Virus (HSV) Types I and II
Recent lifelong viral infections characterized by vesicular lesions.
Symptoms can appear 2 days to 2 weeks after contact, with grouped vesicles appearing on a reddened base.
Treatment Options:
Soothing moist compresses, petroleum jelly.
Antiviral agents like acyclovir (Zovirax) or valacyclovir (Valtrex).
Herpes Zoster (Shingles)
Reactivation of varicella-zoster virus, with a linear distribution of grouped vesicles along a dermatome.
Treatment involves antiviral medications like acyclovir within 72 hours of onset to prevent post-herpetic neuralgia.
Infestations
Pediculosis (Lice)
Types:
Body lice, pubic lice (crabs), and head lice.
Common treatment includes topical pyrethrins or spinosad.
Scabies
Caused by Sarcoptes scabiei.
Characterized by severe itching, especially at night with a presence of burrows on the skin.
Treatment:
Permethrin topical lotion, treat all family members and environments to prevent recurrence.
Dermatitis Conditions
Allergic Contact Dermatitis
A type IV delayed hypersensitivity response.
Lesions appear 2-7 days after contact with an allergen.
Typical treatment includes corticosteroids, antihistamines, and elimination of contact allergens.
Atopic Dermatitis
A type I hypersensitivity response genetically influenced.
Associated with allergic rhinitis and asthma, characterized by chronic, relapsing stages.
Treatments include lubrication of dry skin and corticosteroids for severe inflammation.