Updated: 10/5/2016

Melanoma

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https://upload.orthobullets.com/topic/6093/images/thumb subungual melanoma.jpg
https://upload.orthobullets.com/topic/6093/images/growth phases.jpg
https://upload.orthobullets.com/topic/6093/images/toe subungual melanoma.jpg
Introduction
  • An aggresive skin malignancy of melanocytic origin
    • types include
      • acral lentiginous melanoma
        • subungual melanoma is a subtype of ALM
  • Epidemiology
    • demographics
      • slightly more common in men (male:female ratio = 1.2:1)
      • age bracket is 50-70yrs
    • location
      • thumb > great toe > index finger
      • sun exposed areas
    • risk factors
      • sun exposure
        • UV radiation suppresses skin immunity, induces melanocyte cell division, produces free radicals, damages melanocyte DNA
      • family history
      • skin characteristics
        • blue eyes, fair hair and complexion, freckling
      • xeroderma pigmentosa
      • familial atypical mole or melanoma (FAMM) syndrome
      • multiple benign and dysplastic nevi
        • dysplastic nevi are a precursor
      • immunesuppression
  • Pathophysiology
    • progresses through phases of growth  
  • Prognosis
    • depth is the most important prognostic factor 
      • < 0.7 mm - survival is 96%
      • > 4.0 mm - survival is 47%
    • poor prognostic factors for melanoma
      • deep lesion
      • male sex
      • lesion on neck or scalp
      • positive lymph nodes and metastases
      • ulceration
    • subungual melanoma has poor prognosis overall with 5yr survival 40-60%
Anatomy
  • Melanocytes
    • derived from neural crest cells
    • found in deepest layer of epidermis, separated from dermis by basement membrane
    • dermis is divided into papillary dermis and reticular dermis
    • subcutaneous tissue is deep to reticular dermis
Classification
  • Breslow classification
    • thickness =< 0.75mm
    • thickness 0.76 - 1.5mm
    • thickness 1.51 - 4mm
    • thickness >4mm
  • Clark classification
    • Level I - involves epidermis (in situ melanoma), no invasion
    • Level II - invades papillary dermis
    • Level III - invades papillary dermis up to papillary-reticular interface 
    • Level IV - invades reticular dermis
    • Level V - invades subcutaneous tissue 
Presentation
  • History
    • pigmented lesion with recent change in shape or size
    • nail trauma
      • subungual melanoma renders the nail dystrophic and vulnerable to trauma
  • Symptoms
    • itching or bleeding
  • Physical exam
    • brown-black pigmented lesionmay ulcerate
    • extension of brown-black pigment of the nail bed or nail plate to the cuticle and nail folds (Hutchinson sign)  
    • characterized by (ABCDEs)
      • Asymmetry
      • Border irregularity
      • Color variation
      • Diameter (<6mm benign)
      • Elevation
      • Enlargement
Imaging
  • CXR
    • indications
      • lungs are often first site of metastases
  • Ultrasound
    • indications
      • diagnose lymph node involvement
  • PET or CT 
    • indications
      • detect metastases
Studies
  • Labs
    • CBC
    • AST and ALT
      • liver metastases
    • LDH 
      • predictive for poor prognosis
  • Histolology 
    • melanocytes with
      • marked cellular atypia
      • invasion into the dermis
      • vacuolated cytoplasm
      • hyperchromatic nuclei with prominant nucleoli
Differential
  • Differentials for melanoma
    • nevi
    • seborrheic keratosis
    • basal cell carcinoma
  • Subungual melanoma is mistaken for 
    • trauma
    • subungual hematoma
    • onychomycosis
Treatment
  • Operative
    • local resection with a 1cm margin
      • indications
        • lesion is < 1mm thick
    • local resection with 1-2cm margin, sentinel node biopsy
      • indications
        • lesion is 1-2mm thick
      • technique
        • if sentinel node biopsy positive perform radical node dissection
    • local resection, lymph node dissection, chemotherapy
      • indications
        • evidence of metastasis
    • amputation
      • indications
        • subungual melanoma
      • outcomes
        • distal amputation with sufficient margins has similar recurrence rates and survival to proximal (carpometacarpal/tarsometacarpal) amputations 
        • may include lymph node dissection and isolated limb perfusion
  • Prevention
    • prevent melanoma with sunscreen and avoiding sun exposure
Complications
  • Recurrence
    • usually regional lymph nodes
 

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