An Aggressive Microcystic Adnexal Carcinoma Infiltrating the Sternum.

Area of Science:

• Dermatology
• Oncology
• Surgical Pathology

Background:

• Microcystic adnexal carcinoma (MAC) is a rare cutaneous neoplasm.
• MAC frequently presents with delayed diagnosis due to its subtle presentation and resemblance to benign lesions.
• Aggressive local invasion and recurrence are characteristic challenges in managing MAC.

Observation:

• A case of a large, recurrent MAC on the sternum is presented.
• The initial diagnosis was misattributed to basal cell carcinoma.
• The tumor demonstrated extensive infiltration into underlying muscle and bone.

Findings:

• The sternal MAC exhibited aggressive behavior, invading deep structures.
• The advanced local invasion rendered the tumor unresectable via Mohs micrographic surgery.
• Recurrence despite prior treatment underscores the challenging nature of MAC management.

Implications:

• This case emphasizes the critical need for high diagnostic suspicion for MAC, especially in recurrent or atypical presentations.
• It highlights the limitations of Mohs surgery in managing deeply invasive MAC.
• Further research into multimodal treatment strategies for unresectable or deeply invasive MAC is warranted.