Melanoma, Superficial Spreading Type



Melanoma, Superficial Spreading Type


Soheil Sam Dadras, MD, PhD

Nicole Carreau










Clinical photograph of a melanoma, superficial spreading type shows darkly pigmented areas surrounding a central area of regression image. (Courtesy J. Wu, MD.)






Low-power magnification of a MM-SST shows a highly atypical compound melanocytic proliferation with mild dermal inflammation with scattered melanophages image.


TERMINOLOGY


Abbreviations



  • Malignant melanoma, superficial spreading type (MMSST)


Definitions



  • Most common variant of invasive melanoma


  • Characterized histologically by lateral expansion of large dermal nests of atypical melanocytes, which appear similar to overlying melanoma in situ cells


CLINICAL ISSUES


Epidemiology



  • Incidence



    • 6th most common cancer in USA with increasing incidence


  • Gender



    • Both men and women, but more common overall in men


  • Ethnicity



    • Typically persons with red hair and skin type I/II, but can occur in other ethnicities


Site



  • Varies according to gender, on the back (in men) and on the legs (in women)


Presentation



  • Large dark brown macule (2.5 cm is average size)


  • Variegated color with shades of tan, brown, black, blue-black, red (inflammation or vascular ectasia), gray and white (zones of regression)


  • Irregular borders


  • Presence of distinctive nodule can signify vertical growth phase


Treatment



  • Surgical approaches



    • Complete excision with clear margins



      • Peripheral margins are determined by depth of invasion (Breslow depth)


Prognosis



  • Varies according to Breslow depth, ulceration, and mitotic index



    • 2010 AJCC criteria for determining prognosis


MACROSCOPIC FEATURES


Size



  • Typically > 1 cm in diameter


MICROSCOPIC PATHOLOGY


Histologic Features

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Melanoma, Superficial Spreading Type
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