Adnexal Clear Cell Carcinoma Exhibiting Comedonecrosis of the Ear: A Rare Case Treated With Mohs Micrographic Surgery

Adnexal clear cell carcinoma exhibiting comedonecrosis (ACCCC) is a rare, cutaneous, malignant neoplasm with limited reported cases since its discovery. ACCCC is characterized by unique clinical and histological features, demanding a precise diagnosis due to its potential for aggressive behavior and early metastases, distinct from other cutaneous tumors with clear cytoplasmic cells. We present the case of an 81-year-old male with a history of multiple non-melanoma skin cancers, who presented with a 5 mm erythematous papule on his left tragus. Initial tangential shave biopsy results were invasive clear cell squamous cell carcinoma that was moderately differentiated. Subsequent Mohs micrographic surgery (MMS) necessitating a full-thickness skin graft reconstruction was performed. Histopathological examination afterward confirmed ACCCC with pleomorphic epithelial cells, clear cytoplasm, and central comedonecrosis. Immunohistochemistry supported adnexal differentiation and squamous features. To our knowledge, this is the fifteenth reported case of ACCCC as well as the first documented case of ACCCC treated with MMS, offering a novel approach to managing this rare malignancy.