Primary cutaneous adenoid cystic carcinoma arising in the axilla: a case report and literature review.

Primary cutaneous adenoid cystic carcinoma (PCACC) is a rare cutaneous adnexal malignancy. Although its clinical course is generally considered more indolent than that of salivary gland-derived counterparts, PCACC exhibits a significant propensity for local recurrence and a notable potential for distant metastasis. Here, we report a rare case of PCACC arising in the right axilla. Based on a comprehensive literature review and statistical analysis of previously reported cases, our findings suggest that a tumor diameter of ≥ 2.0 cm may be associated with an increased risk of metastasis. Therefore, for patients with tumors exceeding 2.0 cm, we suggest that careful determination of surgical margins and comprehensive staging evaluations-including whole-body PET-CT, sentinel lymph node biopsy, and long-term postoperative follow-up-may be considered.