Abstract
Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine skin tumor that occurs mainly in the sun-exposed head and neck region, but rarely in the eyelid region. Early lymphogenic
spread often leads to locoregional metastases, which is why early diagnosis is crucial. Classically, periocular MCC presents as a reddish-livid nodule in elderly patients, a visual
diagnosis. However, given its low incidence and variable appearance, diagnosis can also be challenging. In both cases presented here, the MCC presented as a skin-colored swelling. In patient
1, the tumor showed a partially deep subaponeurotic localization and mimicked a B-cell lymphoma histopathologically, whereas in patient 2 it imitated a diffuse chalazion clinically. After
immunohistochemical characterization and exclusion of metastases, the initial clinically benign appearing lesions in both patients were classified as CK20 negative MCC. The extensive upper
eyelid defects were reconstructed by Cutler-Beard plastic surgery, a particular challenge in patient 1 given the oculus unicus situation. Our two cases demonstrate that Merkel cell
carcinomas not only manifest as deep red cherry-shaped tumors, but can be skin-colored and mimic benign changes when atypical in location or infiltration pattern.
Key words
Merkel cell carcinoma - masquerade - immunohistochemistry - diagnostics - therapy
