Superficial spreading melanoma vs Nodular, lentigo maligna, and acral lentiginous melanoma
How to tell Superficial spreading melanoma and Nodular, lentigo maligna, and acral lentiginous melanoma apart when a board question makes them look alike.
Superficial spreading is common radial trunk/leg; nodular is early vertical nodule; lentigo maligna is older sun-damaged face; acral is palms/soles/nails.
Side by side
Superficial spreading melanoma is the most common subtype, with radial growth and irregular pigmented lesion on trunk or legs.
Nodular melanoma grows vertically early; lentigo maligna occurs on sun-damaged face of older adults; acral lentiginous occurs on palms, soles, or nail beds.
Radial intraepidermal melanocyte spread precedes invasion in superficial spreading subtype.
Other subtypes differ by vertical growth tempo or anatomic/UV exposure pattern.
Irregular multicolored lesion with radial growth on trunk supports superficial spreading melanoma.
Rapidly growing dark nodule supports nodular; facial macule in older adult supports lentigo maligna; subungual/palm/sole lesion supports acral lentiginous.
The trap
All four subtypes are melanoma, so growth pattern, anatomic site, and patient demographics decide. SUPERFICIAL SPREADING melanoma (most common, about 70 percent) starts with prolonged radial growth phase (horizontal spreading) before vertical invasion, classically on trunk in men and lower extremities in women; ABCDE features (Asymmetry, Border irregular, Color variegation, Diameter above 6 mm, Evolution). NODULAR melanoma skips radial growth and goes straight to vertical invasion, appearing as a rapidly growing dark nodule on any anatomic site; aggressive, poor prognosis even when small. LENTIGO MALIGNA melanoma arises on sun-damaged skin in older adults (face, neck, dorsal hands) from in-situ lentigo maligna with very long radial growth phase before invasion; better prognosis. ACRAL LENTIGINOUS melanoma is on palms, soles, and subungual nails in dark-skinned patients (most common melanoma subtype in African Americans and Asians); ABCDE on a thumbnail with Hutchinson sign (pigment extending to proximal nail fold) is the high-yield clue. Breslow depth (thickness in mm) is the single most important prognostic factor; sentinel lymph node biopsy if depth above 0.8 mm.
The repair move
For melanoma subtypes, match growth pattern and anatomic site before naming the subtype.
Try a free question
CoreA 38-year-old woman has a 10 mm asymmetric pigmented lesion on her lower leg with irregular borders and multiple colors. Histology shows malignant melanocytes spreading laterally within the epidermis (pagetoid spread) with minimal vertical invasion. Which melanoma subtype is most likely?
Show answer and explanation
Answer: A. Superficial spreading melanoma. Superficial spreading melanoma is the most common subtype (~70%) with predominantly RADIAL growth phase (lateral spread) before vertical invasion; affects intermittently sun-exposed skin on the trunk (men) and legs (women).
Why the other choices are tempting
- B. Nodular melanoma has rapid VERTICAL growth phase with little radial spread.
- C. Lentigo maligna melanoma occurs on chronically sun-damaged skin in older patients.
- D. Acral lentiginous melanoma occurs on palms, soles, and nail beds.
- E. Desmoplastic melanoma has spindle-shaped cells with prominent stromal desmoplasia.
Flashcards
Tap a card to flip it.
Which melanoma subtype grows vertically early?
Nodular melanoma grows vertically early.
Which subtype affects palms, soles, or nail beds?
Acral lentiginous melanoma affects palms, soles, or nail beds.
Quick answers
What is the fastest way to tell Superficial spreading melanoma from Nodular, lentigo maligna, and acral lentiginous melanoma?
Superficial spreading is common radial trunk/leg; nodular is early vertical nodule; lentigo maligna is older sun-damaged face; acral is palms/soles/nails.
What is the key clue for Superficial spreading melanoma?
Superficial spreading melanoma is the most common subtype, with radial growth and irregular pigmented lesion on trunk or legs.
What is the key clue for Nodular, lentigo maligna, and acral lentiginous melanoma?
Nodular melanoma grows vertically early; lentigo maligna occurs on sun-damaged face of older adults; acral lentiginous occurs on palms, soles, or nail beds.
What is the common trap with Superficial spreading melanoma vs Nodular, lentigo maligna, and acral lentiginous melanoma?
All four subtypes are melanoma, so growth pattern, anatomic site, and patient demographics decide. SUPERFICIAL SPREADING melanoma (most common, about 70 percent) starts with prolonged radial growth phase (horizontal spreading) before vertical invasion, classically on trunk in men and lower extremities in women; ABCDE features (Asymmetry, Border irregular, Color variegation, Diameter above 6 mm, Evolution). NODULAR melanoma skips radial growth and goes straight to vertical invasion, appearing as a rapidly growing dark nodule on any anatomic site; aggressive, poor prognosis even when small. LENTIGO MALIGNA melanoma arises on sun-damaged skin in older adults (face, neck, dorsal hands) from in-situ lentigo maligna with very long radial growth phase before invasion; better prognosis. ACRAL LENTIGINOUS melanoma is on palms, soles, and subungual nails in dark-skinned patients (most common melanoma subtype in African Americans and Asians); ABCDE on a thumbnail with Hutchinson sign (pigment extending to proximal nail fold) is the high-yield clue. Breslow depth (thickness in mm) is the single most important prognostic factor; sentinel lymph node biopsy if depth above 0.8 mm.