title: Superficial spreading melanoma
text: # Superficial spreading melanoma
  
  Superficial spreading melanoma (SSM) is a type of skin cancer that typically starts as an irregularly edged dark spot typically on sun-exposed part of the body. The colour may be variable with dark, light and reddish shades; occasionally no color at all. It typically grows in diameter before spreading to deeper tissue, forming a bump or becoming an ulcer. Itching, bleeding and crust formation may occur in some. The backs and shoulders of males and legs of women are particularly prone.
  
  It is a type of melanocytic tumor occurring in intermittently sun-exposed skin. The cause is associated with repeated sunburns in childhood, intermittent exposure to sun during life, and sun bed use.
  
  Two-thirds of cases occur in light skin, and it less common in dark skin.
  
  The average age at diagnosis is in the fifth decade.
  
  ## Signs and symptoms
  
  Often, this disease evolves from a precursor lesion, usually a dysplastic nevus. Otherwise it arises in previously normal skin. A prolonged radial growth phase, where the lesion remains thin, may eventually be followed by a vertical growth phase where the lesion becomes thick and nodular. As the risk of spread varies with the thickness, early SSM is more frequently cured than late nodular melanoma.
  
  ## Histopathology
  
  The microscopic hallmarks are:
  
  * Large melanocytic cells with nest formation along the dermo-epidermal junction.
  * Invasion of the upper epidermis in a pagetoid fashion (discohesive single cell growth).
  * The pattern of rete ridges is often effaced.
  * Invasion of the dermis by atypical, pleomorphic melanocytes
  * Absence of the 'maturation' typical of naevus cells
  * Mitoses
  
  ## Treatment
  
  Treatment is by excisional biopsy, wide local excision and possibly sentinel node biopsy. Localized melanoma, which has not spread beyond the skin, has a very good prognosis with low recurrence rates. Spread of disease to local lymph nodes or distant sites (typically brain, bone, skin and lung) marks a decidedly poor prognosis.
  
  