Lecture 15 - Melanoma Flashcards
Epidemiology
mortality rates have declined rapidly
Pathogenesis
melanocytes are dendritic pigmented cells that arise from neural-crest tissue furing early fetal development and migrate to sites within body
located in skin, uveal tract, meninges, and ectodermal mucosa
melanocytes synthesize melanin to protect tissues from UV radiation induced damage
Melanoma results from
the malignant transformation of skin melanocytes or from the transformation of preexisting nevocellular nevi
number of growth factors, immune factors, and tumor antigens identified in progression of melanoma: BRAF, MEK, P13K/AKT, c-KIT, cytotoxic T lymphocytes, PD-1
Cutaneous melanoma is characterized by growth patterns:
superficial spreading melanoma
nodular melanoma
lentigo maligna melanoma
acral lentiginous melanoma
uveal melanoma
Superficial spreading melanoma
lesions arise from pre-existing nevus
initially appears flat but becomes irregular and asymmetrical
more common in women
Nodular melanoma
strictly vertical growth, more aggressive tumors
appear dark blue-black in color and are raised and asymmetrical
more common in men
Lentigo maligna melanoma
infrequent type, presents on face of elderly
tan lesion with areas of brown and black
Acral lentiginous melanoma
frequently presents on palms, soles, or under nail beds; lesions have irregular convoluted borders
appear as brown stains
more common in african americans, asians, hispanics
Uveal melanoma
arises from pigmented epithelium of choroid
most common ocular melanoma
often metastasis in liver
Clinical presentation
ABCDE: asymmetric, irregular borders, wide variety of colors, diameter of >6mm, evolution of mole may be indicative of neoplastic transformation
Diagnostic work up
biopsy of suspected lesion is gold standard
for suspicious lesions: wide-local excision with removal of underlying subcutaneous fat
sentinel-node biopsy for determining if melanoma has invaded lymph node beds
if melanoma is a clinical or pathologic stage IV, tumor tissue should be tested for BRAF V600E and K mutations
Surgery
margins may need to accomodate anatomical or cosmetic consideration
Mohs surgery
surgery beyond localized disease is palliative
Radiation
could be offered in adjuvant setting for select pts with + lymph nodes and high risk of relapse
Adjuvant treatment
recommendations based on stage
Treatment overview: stage IB or IIA (lymph node negative)
clinical trial or observation
Treatment overview: stage IIB or IIC (lymph node negative)
clinical trial, observation, pembrolizumab