Updated: 6/22/2021

Melanoma

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https://upload.orthobullets.com/topic/6093/images/thumb subungual melanoma.jpg
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https://upload.orthobullets.com/topic/6093/images/toe subungual melanoma.jpg
  • summary
    • Melanomas are an aggressive skin malignancy of melanocytic origin.
    • The condition is typically seen in patients between 50 and 70 years old who present with a pigmented skin lesion with a recent change in shape or size.
    • Diagnosis is made with a biopsy showing melanocytes with marked cellular atypia with invasion into the dermis.
    • Treatment is usually wide surgical excision. 
  • Epidemiology
    • Demographics
      • slightly more common in men (male:female ratio = 1.2:1)
      • age bracket is 50-70yrs
    • Anatomic 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
  • Etiology
    • Forms 
      • types include
        • acral lentiginous melanoma
          • subungual melanoma is a subtype of ALM
    • Pathophysiology
      • progresses through phases of growth
  • 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
    • 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 lesion, may 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
  • Histology
    • 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
  • 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%
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(OBQ13.213) A 55-year-old man presents with a lesion of his right thumb. A clinical photograph and biopsy of the lesion are shown in Figures A and B. Lesion thickness is 0.6mm. Which treatment is recommended to provide the best chance of cure while preserving function?

QID: 4848
FIGURES:
1

Chemotherapy to downsize the tumor, followed by resection with a 1-2mm margin.

8%

(407/5120)

2

Moh's micrographic surgery

19%

(984/5120)

3

Disarticulation at the interphalangeal joint and sentinel lymph node biopsy

64%

(3264/5120)

4

Disarticulation at the metacarpophalangeal joint and sentinel lymph node biopsy

6%

(312/5120)

5

Ray amputation, lymph node dissection and hyperthermic isolated limb perfusion

2%

(92/5120)

L 3 C

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