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Review
. 2022 Nov;126(6):1080-1086.
doi: 10.1002/jso.27010. Epub 2022 Jul 9.

Merkel cell carcinoma of unknown primary: Clinical presentation and outcomes

Samuel E Broida  1 , Xiao T Chen  1 , Christian L Baum  2 , Jerry D Brewer  2 , Matthew S Block  3 , James W Jakub  4 , Barbara A Pockaj  5 , Robert L Foote  6 , Svetomir N Markovic  3 , Tina J Hieken  7 , Matthew T Houdek  1
Affiliations
Review

Merkel cell carcinoma of unknown primary: Clinical presentation and outcomes

Samuel E Broida et al. J Surg Oncol. 2022 Nov.

Abstract

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.

Keywords: Merkel cell carcinoma; lymph node; outcome; unknown primary.

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References

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