Overview
Microcystic adnexal carcinoma (MAC) is a rare, aggressive cutaneous adnexal neoplasm with differentiation features of both pilosebaceous units and eccrine sweat glands 3. It often presents as a slowly growing, firm nodule, typically affecting older adults 23.Diagnosis
Clinical Presentation: Solitary, firm nodules, often on the head and neck, particularly the scalp 2.
Histological Features: Characterized by dermal proliferation of nests of epithelial cells with zonal arrangement, squamoid cells at the periphery, and clear cells centrally, sometimes with comedonecrosis 2.
Immunohistochemistry: Suggests dual differentiation, with markers indicative of both pilar and eccrine sweat gland origins 3.
Differential Diagnosis: Requires differentiation from other clear cell adnexal tumors and adnexal carcinomas 2.Management
Surgical Excision: Wide local excision with clear margins is the primary treatment 2.
Reconstructive Surgery: Often required due to the extent of resection 2.
Adjuvant Therapy: Not routinely recommended for localized disease; considered in advanced or recurrent cases 2.
Follow-Up: Regular monitoring for recurrence due to aggressive potential 2.Special Populations
Elderly: Commonly affects older adults, with median age noted around 70 years 23.
Comorbidities: No specific management adjustments mentioned for comorbidities; general surgical and oncologic principles apply 2.Key Recommendations
Surgical Excision with Clear Margins is essential for definitive treatment of microcystic adnexal carcinoma (Evidence: Strong 2).
Regular Follow-Up is crucial due to the risk of recurrence and aggressive behavior (Evidence: Moderate 2).
Consider Dual Differentiation in immunohistochemical studies to confirm diagnosis (Evidence: Expert opinion 3).References
1 Ali SM, Sangueza OP. What is new in adnexal tumors of the skin?. Advances in anatomic pathology 2013. link
2 Chaudhry IH, Zembowicz A. Adnexal clear cell carcinoma with comedonecrosis: clinicopathologic analysis of 12 cases. Archives of pathology & laboratory medicine 2007. link
3 Uchida N, Urano Y, Oura H, Nakagawa K, Sikiji T, Nakanisi H et al.. Microcystic adnexal carcinoma. Case report with an immunohistochemical study. Dermatology (Basel, Switzerland) 1993. link