Merkel cell carcinoma of unknown primary: Clinical presentation and outcomes

Samuel E. Broida, Xiao T. Chen, Christian L. Baum, Jerry D. Brewer, Matthew S. Block, James W. Jakub, Barbara A. Pockaj, Robert L. Foote, Svetomir N. Markovic, Tina J. Hieken, Matthew T. Houdek

Research output: Contribution to journalArticlepeer-review


Background: Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy that usually occurs in the head/neck or extremities. However, there are reports of MCC developing in the lymph nodes or parotid gland without evidence of a primary cutaneous lesion. Methods: We reviewed 415 patients with biopsy-proven MCC. Patients with MCC of unknown primary (n = 37, 9%, MCCUP) made up the study cohort. The primary endpoints of the study were rate of recurrence, disease-free survival, and overall survival. Results: Patients with MCCUP presented with tumors in lymph nodes (n = 34) or parotid gland (n = 3). Nodal disease was most commonly detected in the inguinal/external iliac (n = 15) or axillary (n = 14) regions. The mean age at diagnosis was 70 years and 24% were female. Patients presented with distant metastases in 24.3% of cases. Patients with stage IIIA disease treated with regional lymph node dissection (RLND) had a lower risk of disease recurrence (hazard ratio 0.26, p = 0.046). Recurrence-free survival was 59.3% at 5 years. Disease-specific survival was 63.3% at 5 years. Conclusion: Patients with MCCUP have a high risk of recurrence and mortality. The optimal treatment for MCCUP has yet to be elucidated, although therapeutic RLND appears beneficial for these patients.

Original languageEnglish (US)
Pages (from-to)1080-1086
Number of pages7
JournalJournal of Surgical Oncology
Issue number6
StatePublished - Nov 2022


  • Merkel cell carcinoma
  • lymph node
  • outcome
  • unknown primary

ASJC Scopus subject areas

  • Surgery
  • Oncology


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