Merkel Cell Carcinoma With True Direct Parotid Gland Invasion

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin malignancy. We report an exceptional case of a 71-year-old female presenting with a 5.7-cm MCC in the left parotid region, representing a rare case of true direct parotid parenchymal invasion-distinguished from the more common intraparotid nodal metastasis-alongside multiple regional nodal metastases. The patient underwent wide en bloc excision, superficial parotidectomy, and selective neck dissection. Despite tumor adherence, the main facial-nerve trunk was successfully preserved. The resulting 12×11 cm composite defect was reconstructed using an anterolateral-thigh (ALT) free flap. Pathology confirmed cutaneous MCC with direct parotid parenchymal invasion, lymphovascular/perineural invasion, and metastatic nodes (Stage IIIB). Postoperatively, the flap remained viable, with successful functional preservation of facial-nerve function. Due to high-risk features, adjuvant chemoradiotherapy was initiated. This case highlights the importance of distinguishing invasion pathways for accurate staging and demonstrates that aggressive resection with functional reconstruction is feasible and effective for managing advanced craniofacial MCC. It also emphasizes the clinical importance of differentiating true parotid invasion from intraparotid nodal metastasis.