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Common sense classification of pigmented lesions

Benign: Lentigo simplex

Solar lentigo

Nevus (Junctional, Dermal, Compound, Blue,

Spitz, Dysplastic)

Potentially malignant:

Atypical melanocytic hyperplasia

Malignant:

Melanoma in-situ

Invasive melanoma

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Melanoma

In-situ InvasiveLentigo maligna Lentigo maligna melanoma

Superficial spreading Superficial spreading(Pagetoid melanoma)

Acral-lentiginous Acral-lentiginous melanoma

None Nodular

None Desmoplastic

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Lentigo simplex

Elongated rete ridges

Basal melanosis

No junctional nest

No solar elastosis

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Solar lentigo

Elongated rete ridges

Basal melanosis

No junctional nest

Dermal solar elastosis

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Nevus: Junctional

Flat epidermal lesion

Junctional nests with clefts

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Nevus: Dermal

Raised lesion

Dermal nests

No junctional nests

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Nevus: Compound

Raised or flat (older person) lesion

Junctional clefted nests and dermal nests

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Nevus: Epithelioid (Spitz nevus)

70% occurs in pts < 20 yrs

Raised, junctional or compound nevus

Epithelioid clefted nests oriented vertically

Cytologic and nuclear pleomorphism

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Nevus: Dysplastic

All ages

Compound nevus

Junctional clefted nests with transverse growth pattern (bridging)

Cytologic and nuclear pleomorphism

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Nevus: Blue

Flat lesion

No junctional nest

Dermal pigmented spindled melanocytes

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Lentiginous nevus

Flat lesion.

Common nevus + lentigo simplex

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Atypical melanocytic hyperplasia

Flat, lentiginous lesion in older people

Junctional melanocytic hyperplasia with small nests

Mild to moderate pleomorphism

Not like any common nevusNot enough for in-situ melanoma

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Melanoma

Lentigo maligna & lentigo maligna melanoma

Superficial spreading ( Pagetoid): In-situ &

invasive

Acral-lentiginous: In-situ & invasive

Nodular: Invasive

Desmoplastic: Invasive

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Melanoma in-situ: Lentigo maligna type

Epidermal atrophy, solar elastosis

Confluent and nested proliferation of pleomorphic melanocytes

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Melanoma in-situ: Lentigo maligna type

Neoplastic melanocytes spread from the junction upwards

and along the adnexa.

No dermal invasion.

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Malignant melanoma: Lentigo maligna type

(Lentigo maligna melanoma)

Tumor has invaded into the dermis

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Superficial spreading in-situ & invasive melanoma

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Acral-lentiginous in-situ & invasive melanoma

Location: foot,toes, hand,fingers

Race: Dark-skinned people

Microscopic appearance: same as lentigo maligna melanoma

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Nodular and Desmoplastic melanoma

No in-situ phaseInvasive at diagnosis

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Nodular melanoma

Raised, ulcerated, no radial spread, deep dermal invasion

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Desmoplastic melanoma

Sun-exposed skin

Older people

Indurated plaque

Spindle cell proliferation in dermis

Solar elastosis

Lymphocyte-plasma cell aggregates

NEED HIGH DEGREE OF SUSPICION

GET S-100 STAIN

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REMEMBER

1. Most (95%) of the pigmented lesions are benign, 4% malignant, 1% borderline.

2. Most (70%) of the melanoma are superficial spreading type.

3. Most of the melanoma occurs in the sun-protected skin.

4. Most of the melanomas occur on the trunk (specially back) of man andlower extremities (specially thigh) of woman.

5. Melanoma is very rare in person below 20 years of age. Exclude Spitz nevus first.

6. If you are not sure of melanoma, do not call MELANOMA. Raise the possibility in

comment, ask for complete resection for further evaluation.

7. Ask for another expert opinion.

8. Do not make wishy-washy and confusing comment in melanoma diagnosis.