Desmoplastic Melanoma (DM)

• Desmoplastic melanoma (DM) is a rare, fibrosing subtype of melanoma:
  • It accounts for 1% to 4 % of all melanoma cases. 
• It is seen typically in elderly patients:
  • Mean age at diagnosis:
    • 66 years 
  • Usually it is found in sun damaged patients:
    • Frequently located on:
      • The head and neck:
        • 53% of the cases
      • Extremities:
        • 26% of the cases
      • Trunk:
        • 20% of the cases
  • Men are reportedly two times more susceptible to DM as compared to women. 
• Usually, DMs present as:
  • Non-pigmented, skin colored and scar-like indurated dermal papules, plaques or nodules:
    • Due to lack of prominent clinical features:
      • The tumors are detected late and most reach significant depth (reticular dermis or even deeper) at the time of diagnosis. 

 

 

• The differential diagnosis includes:
  • Neurofibroma
  • Spindle cell sarcoma
  • Schwannoma
  • Dermatofibroma
  • Blue nevus
  • Fibromatosis
  • Scar
• DMs are sometimes associated with neurotropism with a tendency of perineural invasion:
  • In these cases the term ‘desmoplastic neurotrophic melanoma’ is used to describe the tumors.
• Dermoscopic evaluation demonstrates that:
  • The majority of DMs lacked melanocytic pigmented structures.
  • All cases of DM had at least one melanoma-specific structure, like:
    • Atypical vascular structures
    • Peppering
    • Blue-white veil
    • Atypical globules
    • Crystalline structures
    • Atypical network
    • In some cases dense collagen fibrils
• Histologically:
  • The lesions have dermal and subcutaneous spindle-shaped cells arranged as a single infiltrate or organized into fascicles.

 

• DMs are subdivided into:
  • Pure DM (pDM):
    • Comprising of entirely or almost entirely desmoplastic components,
  • Combined DM (cDM):
    • Comprising of a desmoplastic component admixed with a non-desmoplastic component. 
• Proteins are downstream of up regulated genes:
  • Identification of specific proteins associated with melanoma progression may provide prognostic indicators and therapeutic targets.
  • DM and superficial spreading melanoma (SSM) have variably expressed proteins:
    • Desmoglein 1 is one protein expressed higher during the development of DM than SSM.
    • Heat shock proteins (HSPs) are uniformly elevated in SSM in comparison with DM:
      • HSPs have been postulated to:
        • Protect tumor cells from destruction by innate immunity
        • Promote cell-cycle dysregulation
        • Promote invasion
        • Promote neovascularization
    • Immunohistochemically:
      • The tumor cells of DM often fail to react with many antibodies such as melan A:
        • But are usually positive for:
          • S100 protein
          • Nerve growth factor receptor
          • SOX10 gene.
    • Neurofibromin 1 is the gene most commonly mutated in DM:
      • 93% of the cases:
        • Usually resulting in non-functional proteins.
    • SOX10 protein is a transcription factor important for neural crest, peripheral nervous system, and melanocytic development:
      • SOX10 is highly specific and sensitive for malignant melanoma:
        • Including DM and spindle cell melanomas:
          • Being expressed 98% of the time
• Surgical excision is the current treatment of choice:
  • Yet, there have not been established optimal margins:
    • Because of the depth of invasion at the time of diagnosis, achieving clear surgical margins upon extirpation becomes difficult.
      • This is especially true in large resections of aesthetically sensitive areas, such as the head and neck.
  • Low incidence of lymph node involvement:
    • Ranging from 4% to 14%:
      • This distinguishes it from other types of melanoma.
    • Low incidence of regional lymph node metastases suggests that elective lymph node dissection is not indicated.
  • There may be benefit to identifying, and histologically evaluating, nerves encountered during the resection.
  • In patients with positive surgical margins:
    • One study showed a local recurrence rate of 14% in radiotherapy patients as compared with 54% in those who did not:
      • Thus, evidence shows adjuvant radiotherapy should be the standard treatment of DM patients with:
        • Positive margins
        • Advanced Clark level
        • Breslow thickness 4 mm or greater
        • Recurrent DM
        • Inoperable DM
        • DM with neurotropism (DNM)
• The type of DM was found to be associated with disease recurrence and patient survival:
  • Positive sentinel node biopsy was more frequently found in cDMs as compared to pDMs
  • cDM patients have a worse prognosis as compared to pDM patients

 

Rodrigo Arrangoiz MS, MD, FACS a head and neck / surgical oncologist and is a member of Sociedad Quirúrgica S.C at the America British Cowdray Medical Center in Mexico City:

• He is an expert in the management of skin cancer including MELANOMA.

  • If you have any questions about the management of melanoma please fill free to contact Dr. Arrangoiz.

  • Article on Melanoma published by Dr. Arrangoiz:

    • http://article.sciencepublishinggroup.com/html/10.11648.j.jctr.20160401.11.html

Training:

• General surgery:

• Michigan State University:

• 2004 al 2010

• Surgical Oncology / Head and Neck Surgery / Endocrine Surgery:

• Fox Chase Cancer Center (Filadelfia):

• 2010 al 2012

• Masters in Science (Clinical research for health professionals):

• Drexel University (Filadelfia):

• 2010 al 2012

• Surgical Oncology / Head and Neck Surgery / Endocrine Surgery:

• IFHNOS / Memorial Sloan Kettering Cancer Center:

• 2014 al 2016

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