Lentigo Maligna Melanoma ICD-10: C43.9

Skin cancer / Melanoma

Often searched as: dark spot on face that keeps growing, age spot that changed, irregular brown patch on face, flat dark mark on cheek, melanoma on face elderly, growing freckle on face, sun damage spot turning into cancer, gray brown patch on skin…

Clinical urgency level

lowmediumhigh

Systems Affected

skinlymph nodes (in invasive/metastatic stage)internal organs (in advanced metastatic disease)

Severity Levels

mild

Lentigo maligna (melanoma in situ) — still confined to the epidermis, no invasion — excellent prognosis with complete excision.

moderate

Early invasive lentigo maligna melanoma with thin Breslow depth (<1mm), no ulceration or metastasis — good prognosis with wide surgical excision ± sentinel lymph node biopsy.

severe

Deeply invasive LMM (>2mm), ulceration, lymph node involvement, or distant metastasis — requires multidisciplinary oncologic management including immunotherapy or targeted therapy.

Red Flags

A large irregular dark brown or gray spot on the face, scalp, or neck that is slowly growing
A previously flat pigmented patch developing a raised or nodular area within it
Color variation within a single spot: shades of brown, black, gray, or even pink-red
A spot with blurry, irregular, or moth-eaten borders
Any pigmented lesion on the face of an elderly person that has been changing over months
A spot that bleeds, ulcerates, or crusts without injury

Clinical Presentation

Lentigo maligna — large irregular pigmented patch on the cheek of an elderly patient

Source: Wikimedia Commons (CC BY-SA 3.0 )

Lentigo maligna melanoma image gallery — DermNet NZ

View gallery on DermNet NZ (image gallery reference)

When to See a Doctor

See a dermatologist immediately if you have a slowly growing irregular brown or gray patch on sun-damaged skin — especially on the face, neck, or scalp of an older adult. Lentigo maligna can look deceptively like a freckle or age spot for years before becoming invasive. Early detection when still in situ is critical — it is the difference between a minor procedure and a major cancer treatment.

Differential Diagnosis

Solar lentigo / age spot (benign — stable, uniform color)
Seborrheic keratosis (raised, waxy — not flat)
Pigmented actinic keratosis
Pigmented basal cell carcinoma
Superficial spreading melanoma
Flat melanocytic nevus (mole)
Post-inflammatory hyperpigmentation

Comorbidities

Extensive actinic damage and solar lentigines (UV damage history)
Previous melanoma or non-melanoma skin cancers
Immunosuppression (transplant, HIV)
Xeroderma pigmentosum
Fair skin and history of chronic sun exposure (outdoor occupations)

Prognosis

Lentigo maligna (in situ) has a near-100% cure rate with complete surgical excision. Once it becomes invasive (lentigo maligna melanoma), prognosis depends on Breslow thickness — thin lesions (<1mm) have 5-year survival rates >95%. With lymph node involvement, survival drops to ~60%; with distant metastasis, to ~25–30% (though modern immunotherapy — nivolumab, pembrolizumab — and targeted therapy — BRAF/MEK inhibitors — have significantly improved these figures. The slow-growing nature of LMM means it is often present for years before diagnosis, making early detection campaigns critical.

Detailed Overview

Causes, Symptoms, and When to Take Action Lentigo maligna melanoma (LMM) represents the invasive form of a melanoma that begins as lentigo maligna—initially confined to the epidermis on sun-damaged skin—and later penetrates into the dermis. It most often develops in older adults and in areas with chronic sun exposure. How It Looks Texture: Early lesions may be flat macules; once invasive, portions may become raised or develop a papular component Color: Irregular pigmentation — shades of brown, tan, gray, black; variegation is common Shape: Asymmetrical patches or macules with ill-defined borders; lesion may enlarge slowly over many years Location: Commonly affects the head and neck; sun-exposed skin on elderly persons Why Does It Appear? Chronic ultraviolet (UV) exposure: Cumulative sun damage over many years is a key risk factor Age: More common in older individuals with decades of sun exposure Skin aging and prior actinic damage: Areas with long-term sun damage are most often affected Genetic and environmental contributions: Mutations related to UV damage, plus factors influencing skin's capacity to repair damage, play roles Should You Be Concerned? Yes. Lentigo maligna itself is melanoma in situ; when the atypical cells invade deeper skin layers, it becomes lentigo maligna melanoma, which carries a higher risk. Indicators that warrant medical evaluation include: Lesion changes in thickness, color, or texture Development of nodular or raised parts in a lesion that was previously flat Signs like bleeding, ulceration, or new symptoms such as itching or pain Can You Prevent It? Full prevention isn't guaranteed, but risk reduction may be achieved by: Protecting skin from sun exposure (e.g., avoiding excessive UV, using shade) Regularly checking sun-exposed skin for any changes Minimizing further skin damage 👉 How Piel AI Can Help Piel AI allows you to follow the visual changes of a lesion over time using periodic imaging. While not a diagnostic tool, it can help you notice suspicious changes to share with a healthcare professional. Summary Lentigo maligna melanoma is the invasive progression of lentigo maligna, starting as a non-invasive lesion on sun-damaged skin. It often appears as irregular, slowly expanding patches with variegated colour on sun-exposed areas in older adults. When it invades, the risk increases. Vigilant monitoring and early evaluation are crucial.

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