Malignant melanoma - definition, epidemiology, pathogenesis and risk factors, clinical
features, special variants of melanoma.
Malignant melanoma dermatoskopy - differential diagnosis, staging, prognostic parameters,
sentinel lymph node biopsy and therapy.
- Malignant Melanoma – malignant tumor of melanocytes, in 50 yo.
▪ Epidemiology: “lifetime risk” for white EU ⬆ from 1:1500 (in 1935) to 1:75 (in 2000). In
Australia & USA risk is 1:25. Uncommon in blacks & Asians. Male-female ratio is 1:1,5.
Most occur in 30-70yo.
▪ Pathogenesis: from neuroectodermal melanocytes
▪ Risk factors: UV, chronic irritation, low melanin in skin & FAMS (Famililal atypical mole
syndrome)
▪ 50% arise de novo, 50% arise from melanocytic nevi
▪ Biology: melanomas have 2 growth phases
▪ Horizonal “radial” phase – melanoma starts with abnormal junctional melanocytes &
expands laterally for long period of time. Tumors in this phase rarely metastasize
▪ Vertical phase – tumor cells break thg basement membrane & grow down into dermis.
Once BM is bridged, melanoma can metastasize.
, ▪ Clinical features:
▪ Types:
▪ Superficial spreading - most common* subtype (60%), in 40-60yo. Dominant early
radial growth results in good prognosis.
◦ Irregularly pigmented, poorly circumscribed, polycyclic macule or plaque
>6mm, on trunk (men) & lower legs (women)
◦ Over time develops hypopigmented areas of tumor regression & new nodules
(representing invasive tumors in vertical growth phase)
◦ Described as “red, white, & blue” tumor
▪ Nodular – (20%) in 40-60yo. Early vertical growth. Poor prognosis
◦ Dark-brown papule or nodule, rarely pink or skin-colored, often ulcerated
(outgrows vasculature & gets traumatized), circumscribed. OBS can be <6mm.
▪ Lentigo maligna melanoma – (10%) in >60yo. Lentiginous proliferation (radial growth).
Good prognosis.
◦ Large irregularly pigmented macule, often with regression areas.
◦ In areas of chronic light exposure, most often face
▪ Acral-lentiginous – (5%) most common melanoma in dark-skinned. Not related to UV
light exposure.
◦ Arises on palms or soles (areas without hair follicles)
◦ Clinical variants:
- Subungual melanoma – may present as dark streak in nail with streaks of
pigment in nail fold “Hutchinson sign” & extension to fingertip.
- Digital melanoma – on tips of toes or fingers.
features, special variants of melanoma.
Malignant melanoma dermatoskopy - differential diagnosis, staging, prognostic parameters,
sentinel lymph node biopsy and therapy.
- Malignant Melanoma – malignant tumor of melanocytes, in 50 yo.
▪ Epidemiology: “lifetime risk” for white EU ⬆ from 1:1500 (in 1935) to 1:75 (in 2000). In
Australia & USA risk is 1:25. Uncommon in blacks & Asians. Male-female ratio is 1:1,5.
Most occur in 30-70yo.
▪ Pathogenesis: from neuroectodermal melanocytes
▪ Risk factors: UV, chronic irritation, low melanin in skin & FAMS (Famililal atypical mole
syndrome)
▪ 50% arise de novo, 50% arise from melanocytic nevi
▪ Biology: melanomas have 2 growth phases
▪ Horizonal “radial” phase – melanoma starts with abnormal junctional melanocytes &
expands laterally for long period of time. Tumors in this phase rarely metastasize
▪ Vertical phase – tumor cells break thg basement membrane & grow down into dermis.
Once BM is bridged, melanoma can metastasize.
, ▪ Clinical features:
▪ Types:
▪ Superficial spreading - most common* subtype (60%), in 40-60yo. Dominant early
radial growth results in good prognosis.
◦ Irregularly pigmented, poorly circumscribed, polycyclic macule or plaque
>6mm, on trunk (men) & lower legs (women)
◦ Over time develops hypopigmented areas of tumor regression & new nodules
(representing invasive tumors in vertical growth phase)
◦ Described as “red, white, & blue” tumor
▪ Nodular – (20%) in 40-60yo. Early vertical growth. Poor prognosis
◦ Dark-brown papule or nodule, rarely pink or skin-colored, often ulcerated
(outgrows vasculature & gets traumatized), circumscribed. OBS can be <6mm.
▪ Lentigo maligna melanoma – (10%) in >60yo. Lentiginous proliferation (radial growth).
Good prognosis.
◦ Large irregularly pigmented macule, often with regression areas.
◦ In areas of chronic light exposure, most often face
▪ Acral-lentiginous – (5%) most common melanoma in dark-skinned. Not related to UV
light exposure.
◦ Arises on palms or soles (areas without hair follicles)
◦ Clinical variants:
- Subungual melanoma – may present as dark streak in nail with streaks of
pigment in nail fold “Hutchinson sign” & extension to fingertip.
- Digital melanoma – on tips of toes or fingers.
