Merkel Cell Carcinoma (MCC)

Merkel Cell Carcinoma (MCC)

Keith Scheller, MD

Table of Contents

Background and Presentation
Diagnosis and Treatment

Background and Presentation

A Rare, Very Aggressive Neuroendocrine Tumor with Early Spread

  • High Risk for Recurrence and Metastasis

Risk Factors

  • Elderly (90% are Over 50 Years Old)
  • White Skin (95%)
  • Male Sex (2.2x Higher Risk than Females)
  • Immunosuppression (HIV, Multiple Myeloma, Chronic Lymphocytic Leukemia, etc.)
  • Merkel Cell Polyomavirus (MCPyV)
  • Sun/UV Exposure

Presentation

  • Firm, Red Lesion
  • Non-Tender
  • The Majority (88%) are Asymptomatic

Merkel Cell Carcinoma 1

Merkel Cell Carcinoma 2

Diagnosis and Treatment

Diagnosis

  • Requires a High Index of Suspicion
  • Often Misdiagnosed as a Benign Lesion Such as a Cyst or Lipoma
  • Definitive Diagnosis Made by Biopsy
  • Evaluate with PET and MRI/CT Preoperatively

Histologic Staining

  • Stain Positive:
    • Cytokeratin 20 (CK20) – Characteristic Paranuclear Dot-Like or Diffuse Cytoplasmic Staining Pattern
    • Various Neuroendocrine Markers (Chromogranin, Synaptophysin, CD56)
  • Stain Negative:
    • Thyroid Transcription Factor (TFF-1)
    • S-100
    • Leuko0cyte Common Antigen (LCA)
    • BCOR

Treatment

  • Primary Treatment: Wide Local Excision (WLE), Sentinel Lymph Node Biopsy (SLNB), and Radiation Therapy
  • Margins: ≥ 1-2 cm
  • Positive Lymph Node: Node Dissection and/or Radiation Therapy
  • Nodal or Distant Metastases: May Consider Systemic Chemotherapy, Radiation, or Surgical Resection if Resectable

Merkel Cell Carcinoma 3

References

  1. Paoli J. Wikimedia Commons. (License: CC BY-SA-4.0)
  2. Peter KD. Wikimedia Commons. (License: CC BY-3.0)
  3. Doc 103. Wikimedia Commons. (License: CC BY-SA-3.0)