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Skin Cancer

Study guide:


  • Skin cancer is a type of cancer characterized by abnormal growth of skin cells.


  • Skin cancer is the most common type of cancer in US.

  • Basal cell carcinoma is the most common type of skin cancer approximately 2.8 million cases are diagnosed yearly in the US.

  • Squamous cell carcinoma is the second most common type of skin cancer. Approximately 700,000 cases of SCC are diagnosed annually in the US.

  • Organ transplant patients are 250 times more likely to have squamous cell carcinoma.

Types of skin cancer:


Sun radiation:

  • UVA & UVB


  • AIDS

  • Organ transplant recipient

  • Immunosuppressive medications

Viruses & infections:

  • HPV

  • HIV

Ionizing radiation:

X-ray or CT

Genetic syndromes:

  • Xeroderma pigmentosum

  • Basal cell navus syndrome

  • Epidermodysplasia verriciformis

  • Occulocutaneous albinism


  • Tanning (artificial UV light)

  • Skin color & ethnicity

  • Aging

  • Smoking

  • Precursor lesion (actinic keratosis, Bowen's disease, and multiple navi)

  • Scars & chronic wounds

  • Secondary to other cancers

Adopted from The causes of skin cancer: A comprehensive review Saladi, R.N., Persaud, A.N.

Note: premalignant tumors like actinic keratosis and Bowen's disease (SCC in situ) are more likely to develop into Non-Melanoma Skin Cancer (NMSC). However, having multiple dysplastic nevi or large congenital nevi are usually associated with melanoma.

Marjolin’s ulcer: a squamous cell carcinoma result from a chronic wound e.g.: previous burn scar (tends to be very aggressive)

Fitzpatrick skin types:

Pathophysiology (for more information please refer to molecular pathogenesis of cancer):

  • Skin cancers exist when mutations occur in the DNA of skin cells.

  • The mutations make the cells grow in an uncontrolled manner forming a mass

        of cancer cells.

  • Basal cell carcinoma sign and symptoms:

    • Translucent skin-colored Nodule with suface telangiectasia.

  • Squamous cell carcinoma signs and symptoms:

    • Red nodule with thick keratotic layer.

  • Melanoma signs and symptoms:

    • A large dark brownish patch.

    • A mole that alters in color, size or feel or bleeding.

    • A small sores with an irregular border that appear red, white, or blue-black.

    • Dark sores on the palms, soles, fingers or toes, or on mucous membranes.

Sites of melanoma metastasis:

  1. Lymph nodes, skin, and subcutaneous tissue 59%

  2. Lung 36%

  3. Liver 20%

  4. Brain 20% (common cause of death!)

  5. Bone 17%

  6. GI 17%


Diagnostic tests:

  • Non-Melanoma skin Cancer (NMSC): Skin biopsy (gold standard) – incisional.

  • Melanoma: Skin biopsy (gold standard) – excisional.

  • ABCDE criteria (USA) criteria for diagnosis of malignant melanoma:

    • Asymmetry of mole.

    • Border irregularity.

    • Color variation.

    • Diameter >6 mm.

    • Evolving (change within time).

  • The Glasgow 7-point checklist for malignant melanoma:

Major Criteria:

  1. Change in size

  2. Change in shape

  3. Change in color

Minor Criteria:

  1. Diameter >6 mm

  2. Inflammation

  3. Oozing (bleeding)

  4. Mild itchiness 


  • NMSC:

    • Surgical excision, cryotherapy, radiotherapy, photodynamic therapy or the topical immunostimulant, imiquimod.

  • Melanoma:

    • The lesion should be excised with a margin of clinically normal tissue around it.

    • Clarke levels and Breslow thickness is used to determine prognosis and further treatment.

    • May involve wider local excision and sentinel lymph node mapping and biopsy.

  • Moh surgery also can be used for treatment of skin cancer that appears in sensitive areas such as eyelid.


  • Sunprotection:

    • Protective clothing.

    • Limiting UV exposure (follow the shade, especially between 10 a.m and 4 p.m).

    • A void using tanning beds.

    • Sunscreen.

  • Avoid other known risk factors (e.g. arsenic).

  • Regular screening for individuals at risk.


1.  Bolognia JL et al. Dermatology. 3rd edition. Elsevier. 2012.

2.  Wolff K et al. Fitzpatrick’s color atlas and synopsis of clinical dermatology. 7th edition. McGraw Hill. 2013.

3.  Kumar, P. and Clark, M. (n.d.). Kumar & Clark's clinical medicine.

4., (n.d.). Skin Cancer Facts - [online] A vailable at: [Accessed 9 Feb. 2015].

5.  Rachael Morris-Jones (2014) ABC of Dermatology, Sixth edn., : JohnWiley & Sons, Ltd.

6.  Tao le, Mathew Sochat, and others (2016) First aid for the usmle step 1, 2016 edn., USA.

7.  BeningRahardjo(

r6EBEG4HyXI/Utc5o5rEGMI/AAAAAAAACTs/lmHgp7R6xsY/s1600/LHR-02-about-LHR-pic-031.png) Face

Care: Analyze your Skin Type, Available at: (Accessed: 16, January, 2014).

8.  Anderson W, Pfeiffer R, Tucker M, Rosenberg P. Divergent cancer pathways for early-onset and late-onset

cutaneous malignant melanoma. Cancer. 2009;115(18):4176-4185.

9.  Saladi R, Persaud A. The causes of skin cancer: A comprehensive review. Drugs Today. 2005;41(1):37.

10. [Internet]. 2016 [cited 23 January 2016]. Available from:


11.  280. Publishing L. Cutaneous cancers and chronic leg ulcers - Servier - Phlebolymphology [Internet]. Servier -

Phlebolymphology. 2014 [cited 23 January 2016]. Available from:

12.  Agabegi S, Agabegi E, Ring A. Step-up to medicine. Philadelphia: Wolters Kluwer/Lippincott Williams &

Wilkins; 2013.

Written by:       Abdulrhman M. Al-Qahtani

Reviewed by:   Mohammed Fahad Aldawoud

Format Editor: Roaa Amer

                        Faisal M. Alamer

Audio recording:
- Read by: Ghada Saleh Ashamed
​- Directed by: Tariq Jawadi
- Audio production: Bayan Alzomaili

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