Patient Characteristics and Outcomes in Clinically Misdiagnosed Patients With Merkel Cell Carcinoma
April 20, 2025
Journal
The Journal of Surgical Research
Publication Date
April 20, 2025
Authors
Merkelcell.org Summary
Merkel cell carcinoma (MCC) is a rare but very aggressive type of skin cancer. It can sometimes look like other, more common skin problems, such as benign cysts. Because of this, MCC is often mistaken for something else until a biopsy — a test where a small piece of the skin is removed and checked under a microscope — is done.
In this study, researchers looked at 96 people whose MCC was first thought to be a different condition before a biopsy confirmed the real diagnosis. They compared them to 13 people whose doctors suspected MCC right away and ordered a biopsy.
MCC was most often mistaken for basal cell carcinoma, squamous cell carcinoma, or a harmless, non-cancerous lump. People whose doctors suspected MCC early usually had smaller tumors that had not yet spread to the lymph nodes or other parts of the body. They also had better outcomes, with the cancer less likely to come back later. In contrast, people whose MCC was mistaken for something else often had more advanced cancer by the time they were correctly diagnosed.
It’s important to remember that this study included only a small number of patients, and the differences between the two groups were not proven with statistics. Still, when doctors first thought the skin problem was something else, treating it incorrectly may have delayed getting a biopsy and the right diagnosis. That said, because MCC is a rare skin cancer, it also would not be practical to suspect MCC in every skin spot that looks similar. This study shows how important it is for both doctors and patients to be aware of MCC — and if a skin spot is growing quickly or not healing, getting a biopsy early can help make sure the correct diagnosis is made as soon as possible.
Abstract
Introduction: 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.
Methods: 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.
Results: 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).
Conclusions: 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.
Keywords: Clinical diagnosis; Differential diagnosis; Merkel cell carcinoma; Misdiagnosis; Prognosis; Recurrence; Survival.
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