A Diagnostically Challenging Parotid Gland Tumor With Hybrid Features

Area of Science:

• Head and Neck Surgery
• Oncology
• Pathology

Background:

• Salivary gland tumors are rare, with pleomorphic adenoma (benign) and mucoepidermoid carcinoma (malignant) being most common.
• Differentiating these tumors histopathologically can be challenging, impacting patient prognosis and treatment.
• Accurate diagnosis is crucial for appropriate management, potentially avoiding unnecessary aggressive treatments.

Observation:

• A 24-year-old woman presented with a three-year history of left parotid gland swelling, which recently became painful and rapidly enlarged.
• Imaging revealed a complex heterogeneous mass in the superficial left parotid gland.
• Ultrasound-guided biopsy diagnosed a cellular pleomorphic adenoma with mucinous and squamous metaplasia.

Findings:

• Cellular pleomorphic adenoma exhibits increased cellularity and mitotic activity, but is benign.
• Mucinous and squamous metaplasia can mimic mucoepidermoid carcinoma on fine-needle aspiration (FNA), posing a diagnostic challenge.
• Histopathological evaluation of the gross specimen with immunohistochemistry confirmed the diagnosis, differentiating it from mucoepidermoid carcinoma.

Implications:

• Misdiagnosis as mucoepidermoid carcinoma could lead to unnecessary neck dissection and adjuvant therapy, increasing morbidity.
• This case underscores the critical role of adequate tissue biopsy for precise parotid gland tumor diagnosis.
• Optimizing patient care relies on accurate histopathological appraisal to guide treatment strategies and improve outcomes.