Melanoma vs BCC, SCC, and actinic keratosis
How to tell Melanoma and BCC, SCC, and actinic keratosis apart when a board question makes them look alike.
Melanoma is ABCDE pigmented melanocyte malignancy; BCC is pearly telangiectatic; SCC is scaly keratinizing; actinic keratosis is rough precursor.
Side by side
Melanoma is malignant melanocyte tumor with ABCDE changes, asymmetric irregular pigmented lesion, vertical growth risk, and metastatic potential.
BCC is pearly papule with telangiectasias; SCC is scaly keratotic or ulcerated lesion; actinic keratosis is rough premalignant sun-damaged plaque.
Mutated melanocytes invade and metastasize, with depth of invasion driving prognosis.
UV-induced keratinocyte tumors range from premalignant actinic keratosis to locally invasive BCC or metastatic-potential SCC.
Breslow depth, atypical melanocytes, and ABCDE lesion changes support melanoma.
Palisading basaloid nests support BCC; keratin pearls support SCC; atypical basal keratinocytes support actinic keratosis.
The trap
Sun-exposed lesions overlap, so pigment asymmetry, pearliness, keratinization, and precursor roughness separate them.
The repair move
For skin cancer, classify melanocyte versus basal or squamous keratinocyte pattern.
Try a free question
CoreA 54-year-old man has a pigmented lesion on his upper back that has evolved over 4 months. The lesion is asymmetric, with irregular borders, multiple colors (brown, black, with a small area of pink), and is 9 mm in diameter. Excisional biopsy shows atypical melanocytes invading the dermis with a Breslow depth of 1.4 mm. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Melanoma. Melanoma is a malignant melanocyte tumor identified by the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolution); Breslow depth determines prognosis and is the strongest predictor of metastasis; treatment is wide local excision with sentinel lymph node biopsy for lesions >0.8-1 mm.
Why the other choices are tempting
- B. Basal cell carcinoma is a pearly, telangiectatic papule, not a pigmented evolving lesion.
- C. Squamous cell carcinoma is a scaly keratinizing red papule or ulcer.
- D. Actinic keratosis is a rough, scaly premalignant lesion in sun-exposed skin.
- E. Seborrheic keratosis is a 'stuck-on' waxy benign brown plaque without atypical features.
Flashcards
Tap a card to flip it.
What rule screens for melanoma?
ABCDE changes screen for melanoma.
What histology supports SCC?
Keratin pearls support squamous cell carcinoma.
Quick answers
What is the fastest way to tell Melanoma from BCC, SCC, and actinic keratosis?
Melanoma is ABCDE pigmented melanocyte malignancy; BCC is pearly telangiectatic; SCC is scaly keratinizing; actinic keratosis is rough precursor.
What is the key clue for Melanoma?
Melanoma is malignant melanocyte tumor with ABCDE changes, asymmetric irregular pigmented lesion, vertical growth risk, and metastatic potential.
What is the key clue for BCC, SCC, and actinic keratosis?
BCC is pearly papule with telangiectasias; SCC is scaly keratotic or ulcerated lesion; actinic keratosis is rough premalignant sun-damaged plaque.
What is the common trap with Melanoma vs BCC, SCC, and actinic keratosis?
Sun-exposed lesions overlap, so pigment asymmetry, pearliness, keratinization, and precursor roughness separate them.