Superficial spreading melanoma
Template:DiseaseDisorder infobox
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Superficial spreading melanoma Microchapters |
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Differentiating Superficial spreading melanoma from other Diseases |
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Diagnosis |
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Treatment |
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Case Studies |
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Superficial spreading melanoma On the Web |
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American Roentgen Ray Society Images of Superficial spreading melanoma |
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Directions to Hospitals Treating Superficial spreading melanoma |
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Risk calculators and risk factors for Superficial spreading melanoma |
For patient information, click here Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Superficial spreading melanoma (SSM) is the most common form of cutaneous melanoma in Caucasians. The average age at diagnosis is in the fifth decade, and it tends to occur on sun-exposed skin, especially on the backs of males and lower limbs of females.
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.
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 is by excisional biopsy, wide local excision and possibly sentinel node biopsy. Spread of disease to local lymph nodes or distant sites (typically brain, bone, skin and lung) marks a decidedly poor prognosis.