Updated: 12/17/2019

Squamous Cell Carcinoma

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Snapshot
  • A 74-year-old man presents to the dermatologist’s office for his annual total body skin exam. His past medical history is significant for multiple actinic keratoses, previously treated with cryotherapy. At this visit, he points to a larger lesion on his ear, complaining that it grew back after last year’s cryotherapy. A shave biopsy was done and pathology reveals malignant cells invading the dermis. He is scheduled for an excision.
Introduction
  • Invasive primary skin malignancy arising from keratinocytes of skin or mucosa
  • Epidemiology
    • common in fair-skinned individuals
    • common in elderly patients
    • 2nd most common form of skin cancer (first is basal cell carcinoma )
    • major risk factor = significant sun exposure (damage to keratinocytes) 
      • actinic keratosis
      • actinic cheilitis
    • other risk factors
      • immunosuppression (similar to treatment for organ transplant)
      • arsenic exposure
      • old scars or burns
      • xeroderma pigmentosum
      • ionizing radiation
  • Pathogenesis
    • typically develop from precursor actinic keratoses, but may arise de novo
    • slow-growing malignancy
    • metastases are rare
  • Keratoacanthoma is a variant of low-grade squamous cell carcinoma
    • grows rapidly and regresses spontaneously
  • Bowen disease is a kind of cutaneous squamous cell carcinoma in situ that usually appears
    • well-demarcated
    • scaly patch or plaque
    • often erythematous; however,
      • can be pigmented or skin colored
Presentation
  • Symptoms
    • typically asymptomatic, but may be tender especially if ulcerated 
  • Physical exam 
    • from actinic keratosis
      • red, poorly defined base with adherent yellow or white scale
    • de novo
      • sharply defined smooth, dull, red, dome-shaped nodule
      • crusted center
    • frequently ulcerates
    • frequently on sun-exposed areas
      • face, neck, hands, ears
      • common on lower lips
      • lesions often against a background of sun-damaged skin
        • atrophy, telangiectasias, blotchy hyperpigmentation
Evaluation
  • Diagnosis by skin biopsy 
    • atypical keratinocytes and malignant cells
    • invasion into dermis
    • keratin “pearls” on histology
Differential
  • Actinic keratosis
  • Actinic cheilitis
Treatment
  • Wide local surgical excision
    • with histologic confirmation of negative margins
  • Radiation if surgery is not an option 
Prognosis, Prevention, and Complications
  • Prognosis
    • if treated, very excellent prognosis
    • lesions on lip, ear, or scalp may be more aggressive
  • Prevention
    • sun avoidance
    • sunscreen use 
  • Complications
    • potential recurrence if immunosuppressed

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(M3.ON.15.9) A 71-year-old man presents to his primary care doctor for a lesion on his skin. The patient states he is generally healthy but has noticed this lesion enlarging over the past several months. He worked in the navy and is not currently taking any medications. His temperature is 98.1°F (36.7°C), blood pressure is 123/83 mmHg, pulse is 85/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam is notable for the finding in Figure A on the patient's head. Which of the following is the most likely diagnosis?

QID: 102763
FIGURES:
1

Actinic keratosis

0%

(0/2)

2

Basal cell carcinoma

0%

(0/2)

3

Melanoma

100%

(2/2)

4

Squamous cell carcinoma

0%

(0/2)

5

Xerosis

0%

(0/2)

M 11 E

Select Answer to see Preferred Response

(M2.ON.14.40) A 67-year-old landscaper presents to his primary care physician for a routine visit. On exam, the physician notes a 2x2 cm rash above his upper lip, shown in Figure A. Upon further questioning, the patient states the rash has been there for weeks, but it hasn’t really bothered him. It is not painful or pruritic. He does not recall any recent bug bites. Which of the following is the most important risk factor for this type of lesion?

QID: 104251
FIGURES:
1

Increasing age

1%

(1/80)

2

Sun exposure

86%

(69/80)

3

Immunosuppression

5%

(4/80)

4

Smoking

1%

(1/80)

5

History of eczema

5%

(4/80)

M 6 D

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Evidence (4)
EXPERT COMMENTS (12)
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