Melanoma Flashcards
Where in the skin are melanocytes found?
Basal layer of the epidermis
Name 3 types melanin
• Eumelanin: most common. Brown and black pigment. Better shield against uv
• pheomelanin: red/yellow pigment. More uv induced reactive oxygen species leading to greater DNA damage
Neuromelanin
Which gene determines skin colour?
Mc1r. Fully functional = more eumelanin
Risk factors malignant melanoma? (10)
Environmental
• uv radiation exposure.
Host
• elderly >50
• fair skinned
• common acquired and atypical dysplastic naevi (>6mm, flat, irregular border, colour variation) especially if multiple and large
• male
• chronic immune suppression: prior cancer (chronic lymphocytic leukemia and non-hodgkin lymphoma ), AIDS, post-transplant
Genetics
• NRAS gene mutation: sun exposed areas, modular melanoma
• BRAF: intermittent childhood exposed skin
• kit: chronically sun exposed areas
• pten:
• family history (cdkn2a gene mutation)
• less common = nucleotide excision repair ner gene → xeroderma pigmentosum
Name 5 types cutaneous malignant melanoma
• Superficial spreading: most common 70%
• nodular melanoma: 15-30%
• lentigo maligna 10-15%
Acral lentiginous 2-8%
• desmoplastic melanoma very rare
Where does superficial spreading cutaneous malignant melanoma commonly occur?
Female: leg
Male: back
Characteristic features of superficial spreading cutaneous malignant melanoma? (5)
• Usually female leg, male back
• diagnosed 5th decade
• flat
• slow growing
• enlarge radially (lateral)
Characteristic features of nodular cutaneous malignant melanoma? (5)
• 6th decade
• male > female
• common sites: head, neck, trunk, legs
• rapidly enlarging, may ulcerate and haemorrhage
• lack typical abcde warning signs with worse prognosis, usually in vertical growth phase at time of diagnosis
Characteristic features of lentigo maligna cutaneous malignant melanoma? (4)
• 8th decade
• chronically sun damaged areas: head, neck, forearms.
• initially flat variegated (different colours) pigmented macule with irregular edges
• later = central nodule indicating transition to vertical growth phase
Characteristic features of acral lentiginous cutaneous malignant melanoma? (5)
• Exclusively on sole, palm and subungal (under nail thumb or great toe ) locations
• most common type dark skinned elderly
• asymmetric brown-black nodule with variegation in colour and irregular borders
• subungal: diffuse nail discolouration, longitudinal pigmented band (melonychia strata) or growth in nail bed. Pigmented spread to lateral nail folds or prox nail fold= Hutchinson sign, pathognomonic
• poorer prognosis
Characteristic features of desmoplastic cutaneous malignant melanoma? (4)
• Older males
• head and neck
• 50% amelanotic scar, 50% overlying lm (lentigo maligna) or SSM (superficial spreading)
• deeply invasive. May be extremely painful of neurotropic
Rare
Differential diagnosis for superficial spreading melanoma? (4)
• Atypical naevus
• melanocytic naevi
• seborrheic keratosis
• superficial basal cell carcinoma
Differential diagnosis for nodular melanoma? (5)
• Blue naevus
• pigmented basal cell carcinoma
• squamous cell carcinoma
• kaposi sarcoma
• angiosarcoma
Differential diagnosis for lentigo maligna melanoma? (5)
• Solar lentigo
• ephelids
• pigmented actinic keratosis
• superficial bcc
• seborrhoeic keratosis
Differential diagnosis for acral lentigenous melanoma? (5)
• Plantar warts
• haematoma
• pyogenic granuloma palmoplantar naevus
• glomus tumour
• haemorrhage under nail
• onychomycosis Bowens disease
Differential diagnosis for desmoplastic melanoma? (4)
• sclerosing blue naevi
• dermato fibroma
• leiomyosarcoma
• malignant fibrous histocytoma
Examination of melanoma?
Abcde
• asymmetry
• border irregularities
. Colour variegation
• diameter > 6mm
• elevation
Investigations and diagnosis melanoma?
• Dermoscopy to reduce number of biopsies benign lesions and increased diagnostic accuracy
• biopsy if suspicious from most elevated or darkest area of lesion
- narrow margin (2mm) complete elliptical excision biopsy best
- punch
- shave
- avoid wide excisions, not as accurate histology
- full thickness of large
staging melanoma?
TNM
Tumour
‘Tis:
T1: ≤1 mm in thickness
T 2: 1,01-2 mm
T3:2,01-4 mm
T 4: > 4 mm
A and b for each: with (B) or without (a) ulceration
Regional lymph nodes
N1:1 node
- A: micrometastasis
-B: macro
N2:2-3 nodes
A-micro
B-macro
C- in transit mets/satellite without metastatic nodes
N3: ≥4 metastatic nodes, or matted, or in transit mets/satellite with metastatic nodes
Metastasis
M1a: skin, subcutaneous or distant lymph nodes
M 1 b: lung
m1c: all other visceral sets or distant metastasis to any site with elevated serum ldh
Clinical staging 1-4 melanoma?
• Stage 1: t1a - T 2 a no MO
• stage 2: t2b - t4 b no m0
• stage 3:≥ n1
• stage 4: M1
Melanoma treatment? (5)
• Wide local excision! 1-2 cm excision around primary tumour
• for regional lymph nodes: complete lymph node dissection, also prophylactic for breslow stage 3-5 (>1,5mm deep )
• alternative if can’t do surgery: topical imiquimod 5% cream
• radiation: can be primary (melanoma in situ and lymph mets if surgery not possible), adjuvant or palliative!
• adjuvant therapy: intralesional injection, local ablation therapy, regional therapy, systemic
Indications for sentinel lymph node biopsy for melanoma? (6)
• T 2-T4
• t1b with adverse features eg ulceration, lymphovascular invasion, high mitotic rate
• patients <40 with other adverse histology features in T1a and t1b
• incomplete biopsy of primary tumour with positive margins
• Clark’s histology levels 2-4 (beyond epidermis )
. Breslow stage 3- 5 (>1.5mm deep)
Contraindication = advanced age, poor functional status, comorbid condition
How do sentinel lymph node biopsy for melanoma?
Pre-operative lymphatic mapping (lymphoscintigraphy) with blue dye injection around primary tumour and gamma probe localisation with Tc 99 sulfur colloids, to identify and remove.
Which type of melanoma will require adjuvant radiotherapy?
Desmoplastic melanoma
Name 4 adjuvant therapy options for melanoma
• Intralesional injection: t-vec, bce, IFN, il 2
• local ablation therapy: topical imiquimod
• regional therapy: isolated limb infusion/perfusion with Melphalan
• systemic therapy: IFN alpha 2b, immunotherapy, BRAF inhibitors, checkpoint inhibitors
• radiotherapy
Describe Clark’s levels of histology for melanoma.
• Level 1: melanoma cells confined to epidermis
• level 2: invasion of single cells or very small nests of melanoma into papillary dermis
• level 3: melanoma cells full and expand the papillary dermis
• level 4: invasion into reticular dermis
• level 5 : Invasion of subcutaneous fat
Describe Breslow’s classification for melanoma and prognosis
• Stage 1: 0,75 mm deep
• stage 2: 0,76-1,5
• stage 3: 1,51-2,25
• stage 4: 2,26 -3,0
• stage 5: > 3mm
Stage 1 and 2 better prognosis
stage 3-5 high risk metastasis, will benefit from prophylactic lymph node dissection
