Unmasking hidden Merkel cell carcinoma recurrences: Three illustrative cases of patients with rising viral oncoprotein antibody levels and challenge of requiring multi-modal imaging to detect clinical disease

May 24, 2024

Journal

Radiology Case Reports

Publication Date

May 24, 2024

Authors

Alexander N, Nghiem P, Chen D, Park S

Merkelcell.org Summary

Merkel cell carcinoma (MCC) is often caused by the Merkel cell polyomavirus (MCPyV). About half of all newly diagnosed MCC patients make antibodies (a type of protein) against MCPyV, which can be measured by the AMERK blood test. The AMERK test helps find out early on whether the cancer has come back (recurrence) and can sometimes find a recurrence before it’s visible on a scan. While the AMERK test is sensitive, imaging still needs to be done to find out where the cancer came back. MCC has specific features that show up on scans, making proper imaging important. PET-CT scans can help in early detection of recurrence, and other imaging methods like MRI and 68Ga-DOTATATE PET-CT, a special type of PET-CT scan, can reveal hidden cancer. If an increase in AMERK is observed without any visible evidence on the body that the MCC has come back, it may be helpful to consider extra imaging or reviewing current imaging to find any hidden cancer. Combining the AMERK test with imaging improves early detection of MCC recurrence, allowing for patients to get treatment quickly and have better outcomes.

Abstract

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a high risk of recurrence and metastasis. Regular surveillance through physical exams and imaging studies is crucial for the timely detection of recurrences. MCC patients who produce antibodies to the Merkel cell polyomavirus oncoprotein may benefit from antibody testing in addition to routine imaging surveillance for the early detection of disease recurrence. The clinically available Anti MERKel cell panel (AMERK) is a sensitive tumor marker for Merkel cell polyomavirus positive MCC.

Although AMERK is highly sensitive, imaging remains necessary to confirm the location of disease recurrence. MCC exhibits characteristic imaging features, making appropriate imaging modalities, and interpretation important for detection.

We present 3 representative patient cases that highlight effective utilization of the AMERK test in addition to imaging for the early detection of MCC recurrence. The rise in the AMERK titer may occur before the disease reaches detectable size on computed tomography scans. Positron emission tomography (PET)-CT can serve as an alternative modality for the early detection of disease. Even subtle abnormalities in 18F-FDG uptake may be significant if accompanied by an increased AMERK titer. Alternative imaging modalities, such as 68Ga-DOTATATE PET-CT and magnetic resonance imaging, can be useful in revealing clinically occult disease in MCC patients.

In summary, the AMERK antibody test, alongside imaging, enhances sensitivity in detecting recurrence. By combining these strategies of blood test and imaging, healthcare professionals can identify early signs of MCC recurrence, leading to prompt interventions and improved patient outcomes.

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