VHOSPITAL.CLINIC · Differential Diagnosis
Melanoma (Skin Cancer) vs Seborrheic Dermatitis
Clinical comparison — shared symptoms, key differences, distinguishing diagnostic tests, treatment pathways, and when to seek urgent evaluation.
Condition Overview
Condition A
Melanoma (Skin Cancer)
Melanoma is the most dangerous form of skin cancer, arising from melanocytes. UV radiation is the primary risk factor; early detection using the ABCDE criteria (Asymmetry, Border, Color, Diameter, Evolution) is critical for survival.
Condition B
Seborrheic Dermatitis
Seborrheic dermatitis is a chronic inflammatory skin condition causing scaly patches and red skin, particularly on the scalp (dandruff), face, and chest. Malassezia yeast overgrowth plays a role; antifungal shampoos and mild topical steroids are effective.
Shared Symptoms — Why They're Confused
Both conditions present with 2 overlapping symptoms, making clinical differentiation essential.
Key Clinical Differences
Melanoma (Skin Cancer)
- Asymmetric, irregular border, multiple colours, diameter >6 mm, evolving
- ABCDE criteria apply
- May bleed, ulcerate, or itch
- Risk: UV exposure, fair skin, family history, >50 moles
Seborrheic Dermatitis
- Waxy, 'stuck-on' appearance with dull surface
- Brown to black well-defined lesion
- Benign — does not evolve rapidly
- More common with age; sebaceous-area distribution
Distinguishing Diagnostic Tests
| Test | Melanoma (Skin Cancer) | Seborrheic Dermatitis |
|---|---|---|
| Dermoscopy | Atypical pigment network, regression, blue-white veil — malignant features | Milia-like cysts, comedo-like openings, hairpin vessels — SK pattern |
| Evolution (ABCDE) | Changing colour, irregular borders, diameter growth, ulceration | Stable for years; no ABCDE criteria met |
| Excisional biopsy | Malignant melanocytes invading dermis — Breslow thickness measured | Benign proliferating epidermal cells — acanthosis without invasion |
Treatment Approaches
Melanoma (Skin Cancer)
- •Wide local excision with margins based on Breslow thickness
- •Sentinel lymph node biopsy
- •Anti-PD1 immunotherapy or BRAF inhibitors for advanced disease
Seborrheic Dermatitis
- •Reassurance — benign lesion
- •Cryotherapy or curettage for cosmetic removal
- •No follow-up required unless diagnosis uncertain
When Doctors Consider Each Diagnosis
🔵 Consider Melanoma (Skin Cancer) when:
- →ABCDE criteria met, evolving, dermoscopy malignant features, biopsy confirms melanoma
🟢 Consider Seborrheic Dermatitis when:
- →Waxy stuck-on appearance, stable, dermoscopy SK features, no ABCDE criteria
Explore Each Condition in Detail
Related Clinical Pages
Melanoma (Skin Cancer)
Medical References
Content on this page is informed by evidence-based clinical sources including:
- World Health Organization (WHO)Global health guidance and disease classification
- National Health Service (NHS)UK clinical guidelines and patient information
- National Institute for Health and Care Excellence (NICE)Evidence-based clinical practice guidelines
- Centers for Disease Control and Prevention (CDC)US public health data and clinical recommendations
- PubMed – NCBIPeer-reviewed biomedical literature and clinical studies
- Cochrane LibrarySystematic reviews and meta-analyses in evidence-based medicine
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