Patient Characteristics and Outcomes in Clinically Misdiagnosed Patients With Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare aggressive cutaneous neuroendocrine carcinoma characterized by poor outcomes. MCC morphology is nonspecific and mimics that of other skin lesions, resulting in misdiagnosis and delayed treatment. This study aims to describe survival outcomes of patients with MCC who were clinically misdiagnosed.

Patients diagnosed with MCC were identified using a single-institution retrospective database. Demographics, tumor characteristics, and diagnostic features were evaluated. The Kaplan-Meier method was used to estimate overall survival and recurrence-free survival.

Out of 109 patients with MCC, 96 (88.1%) were initially misdiagnosed based on clinical examination before histopathological confirmation of MCC. Common misdiagnoses included basal cell carcinoma (n = 32, 29.4%), squamous cell carcinoma (n = 23, 21.1%), and benign cyst (n = 21, 19.3%). Misdiagnosed patients had a larger median tumor size of 1.8 cm, whereas correctly diagnosed patients had a median tumor size of 1.5 cm. Patients with correct initial diagnosis tended to have negative nodal disease (87.5% versus. 50.0%) and early-stage disease (stage I-II: 76.9% versus. 44.7%). Patients who were misdiagnosed had a lower median overall survival compared to those who were not (74.6 mo versus. 120.6 mo, P = 0.414). Median recurrence-free survival among those who were misdiagnosed was 52.6 mo, whereas it was not reached in the correctly diagnosed group (P = 0.068).

The nonspecific appearance of MCC poses diagnostic challenges in nonacademic health care settings. Given that patients who were clinically misdiagnosed had worse survival, heightened awareness of MCC and early referral to tertiary medical centers are crucial to ensuring optimal patient outcomes for this rare disease.