Clues Pointing TO This Diagnosis

54-year-old man with 30 years of outdoor/occupational sun exposure — chronic and intermittent UV exposure, male sex, and older age are established melanoma risk factors
A pre-existing back mole that recently changed — a changing pigmented lesion is the most common melanoma complaint and reflects the "E" (evolution) criterion
Asymmetry (one half unlike the other) — the "A" of ABCDE, a core visual feature of melanoma
Ragged/irregular borders — the "B" of ABCDE, characteristic of malignant melanocytic lesions
Color variegation with shades of brown and black — the "C" of ABCDE, multiple colors within one lesion suggest melanoma
Diameter larger than a pencil eraser (>6 mm) — the "D" of ABCDE
Slightly raised/evolving surface over time — supports the "E" (evolving) criterion and warrants biopsy
Truncal (back) location — superficial spreading melanoma from intermittent sun exposure typically arises on the trunk in this age group
Excisional biopsy confirming melanoma with a Breslow thickness of 1.2 mm — histopathology is the diagnostic gold standard, and Breslow thickness drives staging and management

Why It's NOT the Similar Diseases

NOT a benign nevus — a stable, symmetric, uniformly colored mole with a regular border does not meet the ABCDE criteria; Clifford's lesion is asymmetric, irregularly bordered, multicolored, >6 mm, and evolving
NOT seborrheic keratosis — these are "stuck-on," waxy, well-demarcated papules lacking true asymmetry/border irregularity, and biopsy here confirmed invasive melanoma
NOT basal cell carcinoma — BCC is typically a pearly, telangiectatic papule that may ulcerate, not a changing pigmented macule/plaque with color variegation confirmed as melanoma on pathology
NOT squamous cell carcinoma — SCC presents as a scaly, hyperkeratotic or ulcerated papule/plaque rather than an asymmetric multicolored pigmented lesion
NOT a dysplastic (atypical) nevus — although a risk marker that can mimic melanoma clinically, the excisional biopsy established invasive melanoma with a measurable Breslow depth

Differential Diagnosis List

Benign melanocytic nevus — ruled out by asymmetry, irregular border, color variegation, >6 mm diameter, evolution, and biopsy-proven melanoma
Dysplastic (atypical) nevus — ruled out by excisional biopsy confirming invasive melanoma with a 1.2 mm Breslow depth
Seborrheic keratosis — ruled out by the evolving, ABCDE-positive appearance and malignant histopathology
Basal cell carcinoma — ruled out by the pigmented, multicolored evolving morphology and melanoma on pathology
Squamous cell carcinoma — ruled out by absence of scaly/keratotic morphology and by melanoma diagnosis on biopsy

Key Distinguishing Test

Full-thickness excisional (complete) biopsy with 1–3 mm margins is the diagnostic procedure of choice; histopathology confirms melanoma and provides the Breslow thickness (here 1.2 mm) and ulceration status that determine staging, surgical margins, and whether sentinel lymph node biopsy is offered.
Superficial shave biopsy is discouraged when suspicion is high because it can transect the lesion and prevent accurate Breslow measurement.

Board Note

Classic associations/risk factors: UV/sun exposure, tanning beds, Fitzpatrick skin type I–II (fair skin, red hair, blue eyes), numerous or atypical/dysplastic nevi, older age, male sex, and personal or family history of melanoma
Use the ABCDE mnemonic (and "ugly duckling" sign) to trigger evaluation; any suspicious or changing pigmented lesion should be biopsied, and dermoscopy by a trained clinician improves diagnostic accuracy
Breslow thickness is the single most important prognostic factor and drives management; wide local excision with margins based on thickness is the primary treatment (roughly 0.5–1 cm for in situ, 1 cm for ≤1 mm, 1–2 cm for 1–2 mm, and 2 cm for >2 mm)
Sentinel lymph node biopsy is discussed/offered for melanomas that are ulcerated or ≥0.8 mm thick (and select thinner lesions with adverse features); a positive node upstages to stage III and informs adjuvant therapy, but completion lymph node dissection is no longer routine
Refer to dermatology/surgical oncology for definitive wide excision and nodal staging; advanced (stage III–IV) disease is managed with immunotherapy and/or BRAF-targeted therapy by oncology
Counsel on lifelong sun protection (broad-spectrum sunscreen, protective clothing, avoiding peak sun and tanning beds), regular skin/lymph node self-exams, and stage-based dermatologic surveillance, since 4–8% of patients develop a new primary melanoma

“Clifford’s Story”