Lentigo Maligna
Also known as: Melanoma in situ (lentigo maligna type)
The earliest stage of a specific melanoma type. A slowly expanding flat brown patch on sun-damaged facial skin.
What to look for
Side-by-side comparison
Age spot
Uniform color, stable
Possible LM
Uneven color, expanding
Lentigo maligna (LM) is a form of melanoma in situ - meaning the malignant melanocytes are confined to the epidermis and have not yet invaded deeper layers. It occurs on chronically sun-damaged skin, most commonly the face (especially the cheeks, nose, and forehead) of elderly individuals.
LM presents as a flat, irregularly shaped, tan-to-dark-brown patch that slowly enlarges over years to decades. It may have areas of varying shades of brown, and its borders are often irregular and poorly defined. It can easily be mistaken for a benign solar lentigo (age spot) or seborrheic keratosis.
If left untreated, lentigo maligna can progress to lentigo maligna melanoma (LMM) - an invasive form of melanoma. The estimated rate of progression to invasive melanoma varies widely in the literature, from 5% to 50% over a patient's lifetime. The unpredictability of progression is why treatment of all lentigo maligna is recommended.
Distinguishing LM from a solar lentigo can be challenging even for experienced dermatologists. Dermoscopy (examination with a polarized light magnifying device) shows characteristic features, and biopsy confirms the diagnosis.
Quick self-check
Does this look like lentigo maligna? Answer 2 questions.
Is it a flat brown patch on sun-damaged facial skin?
Has it been slowly growing or changing over months to years?
The ABCDE Rule — Visual Guide
The screening method dermatologists recommend for self-examination.
Asymmetry
One half does not match the other half
Normal
Both halves match
Warning
Halves don't match
Border
Edges are irregular, ragged, or blurred
Normal
Smooth, well-defined edge
Warning
Ragged, blurred edges
Color
Multiple colors or uneven color distribution
Normal
One uniform color
Warning
5+ colors mixed
Diameter
Larger than 6mm — about the size of a pencil eraser
Normal
Under 6mm
Warning
Over 6mm (pencil eraser)
Evolution
Any change in size, shape, color, or symptoms over time
Normal
No change over 12 months
Warning
Grew, darkened, irregular
Most important: Evolution (E) is considered the single most critical criterion. Any mole that is changing — in size, shape, color, or producing new symptoms like itching or bleeding — should be evaluated by a dermatologist regardless of other features. This guide is for screening only.
Risk factors
- Chronic cumulative sun exposure on fair skin
- Age over 60 (median age 65-70)
- History of significant sun damage (solar elastosis)
- Previous skin cancer or actinic keratosis
When to see a dermatologist
- ⚠A flat brown patch on the face that has been slowly expanding
- ⚠An age spot that is changing shape, developing irregular borders, or showing color variation
- ⚠Any pigmented lesion on sun-damaged skin that looks different from others
Often confused with
Not sure if this is lentigo maligna? Compare:
Want a more detailed check?
Our full ABCDE checker evaluates 5 clinical criteria in 30 seconds.
Full ABCDE check →Frequently asked questions
Is lentigo maligna the same as melanoma?
Lentigo maligna is melanoma in situ - the very earliest stage, confined to the top layer of skin with no ability to spread. If untreated, it can progress to lentigo maligna melanoma, which is invasive and can metastasize. This is the reason treatment at the in situ stage is strongly recommended.
How do I tell lentigo maligna from an age spot?
Age spots (solar lentigines) tend to be evenly colored with well-defined borders. Lentigo maligna typically shows uneven coloring with multiple shades of brown, irregular borders, and tends to slowly expand. Dermoscopic examination by a dermatologist can distinguish them. When in doubt, a biopsy provides a definitive answer.
Related conditions
Melanoma
The most dangerous skin cancer - but 99% survival when caught early. Learn the ABCDE signs.
Solar Lentigo
Flat brown spots from cumulative sun exposure. Completely harmless - but sometimes confused with lentigo maligna (early melanoma).
Actinic Keratosis
Rough, sandpaper-like patches from years of sun damage. The most common precancer - 5-10% progress to squamous cell carcinoma.