Primary Cutaneous Apocrine Carcinoma of the Neck Involving the Parotid Gland: A Case Report and Review of the Literature

Introduction: Primary cutaneous apocrine carcinoma (PCAC) is a rare skin malignant tumor that originates from areas with a high concentration of apocrine glands. The incidence of PCAC in the neck is relatively low. The age of onset in PCAC ranges from 5 to 70 years old. Clinically, PCAC typically shows up as painless nodules or lumps. In immunohistochemistry, positive expression of CK-7, GCDFP-15, AR, and myoepithelial markers are helpful in the diagnosis of PCAC. This case report pertains to a 59-year-old male of Asian descent. Five years ago, a painless mass was discovered behind his right ear, which grew slowly. This patient was identified as PCAC based on clinical symptoms, pathology, immunohistochemistry, and imaging characteristics. PCAC involved the parotid gland in this case; it is easy to be misdiagnosed as a primary malignant tumor of the parotid gland on imaging. Furthermore, a thorough set of clinical, imaging, pathological, and immunohistochemical examinations must be performed to make a diagnosis because it is challenging to differentiate PCAC from metastatic breast carcinoma. Conclusion: A well-developed multidisciplinary examination is essential because PCAC can be challenging to diagnose and differentiate.