Abstract / Summary
Background: Microcystic adnexal carcinoma (MAC) is a rare cutaneous adnexal malignancy characterized by slow clinical growth but pronounced local aggressiveness, extensive subclinical infiltration, and a propensity for perineural invasion. Owing to its rarity and often inconspicuous clinical presentation, diagnosis and treatment remain challenging, particularly in the anatomically complex head and neck region. Methods: A narrative review of the literature was performed using PubMed/MEDLINE and Embase, covering publications available up to August 2026. Relevant studies addressing the clinical presentation, diagnostic work-up, histopathology, imaging, surgical and non-surgical treatment, recurrence, and follow-up of MAC were reviewed, with particular emphasis on MAC arising in the head and neck region. Results: Adequate deep biopsy extending into the subcutaneous tissue is essential for reliable diagnosis, as superficial sampling may result in misdiagnosis. Contrast-enhanced magnetic resonance imaging may be considered when deep infiltration or clinically significant perineural spread is suspected, although MAC-specific imaging evidence is limited. Complete surgical excision with comprehensive microscopic margin assessment represents the cornerstone of treatment. Mohs micrographic surgery or staged excision with comprehensive peripheral and deep margin assessment may be favored when technically feasible; comparative evidence is retrospective and does not establish a survival advantage. More extensive oncological resection may be required for tumors involving deep structures or major nerves. Elective treatment of the clinically negative neck is generally not indicated because regional metastases are uncommon. Radiotherapy has a selective role in patients with high-risk features, unresectable disease, or inadequate surgical margins, but supporting evidence remains predominantly retrospective. Conclusions: Management of head and neck MAC should focus on accurate diagnosis and durable local and perineural disease control. Available evidence and expert guidance favor margin-controlled surgery, with radiotherapy considered selectively; the optimal treatment and surveillance strategies have not been prospectively established. Given the potential for late recurrence, prolonged clinical surveillance is warranted.