First Reported Case of Intraparotid Lymph Node Metastasis from Eccrine Porocarcinoma of the Auricular Concha: A Case Report with Long-Term Follow-Up.

Background: Eccrine porocarcinoma (EP) is a rare adnexal malignancy with aggressive potential and a predilection for local recurrence and metastasis. The auricular concha is an exceptional site of origin, and intraparotid metastasis has not been previously reported.

Case presentation: We report a 55-year-old immunosuppressed male, kidney transplant recipient, with a slowly enlarging pigmented ulcerated lesion of the left auricular concha. Wide local excision with flap reconstruction confirmed EP on histopathology and immunohistochemistry, with negative margins and no perineural or lymphovascular invasion. After 13 months, a hypermetabolic lesion within the left parotid gland was revealed. Total parotidectomy with ipsilateral modified radical neck dissection confirmed intraparotid lymph node metastasis of EP, with no additional nodal involvement. Adjuvant radiotherapy was delivered.

Conclusions: This is the first documented case of intraparotid lymph node metastasis from head and neck EP, and the metastatic case with the longest disease-free follow-up reported (36 months). The case underscores the diagnostic pitfalls of EP, the need for long-term surveillance, and the importance of systematic parotid evaluation, including ultrasound, in head and neck cases.