Diagnostic challenge of a lower eyelid swelling: A vascular thrombus mimicking a dermoid cyst.

Eyelid and periorbital lesions encompass a wide range of etiologies and clinical presentations, often posing diagnostic challenges. We report a case of a right lower eyelid mass that was initially referred to as a nonresolving chalazion. Clinical suspicion suggested a vascular lesion; however, magnetic resonance imaging indicated a dermoid or epidermoid cyst. Definitive diagnosis was achieved through histopathological examination of the excised specimen, which revealed a vascular thrombus originating from a true aneurysm of an artery. In the absence of a clear history of trauma, infection, or a systemic illness, an unrecognized injury was considered the most plausible explanation. To the best of our knowledge, a vascular thrombus arising from a true arterial aneurysm involving the lower eyelid has not been previously reported. This case report underscores the importance of comprehensive clinical, radiological, and histopathological evaluation in the assessment of atypical eyelid lesions.