Chaotic transformation of parotid acinic cell carcinoma to metastatic dedifferentiated high-grade pathology - A rare case with clinical and emotional challenge.

Introduction And Importance: Acinic cell carcinoma (AciCC) is a rare entity in which high-grade transformation (HGT), formerly dedifferentiation, is uncommon. This case report presents a rare case of AciCC, with rapid transformation to metastatic high-grade dedifferentiated pathology after initial curative treatment.

Case Presentation: A 58-year-old woman presented in the medical oncology clinic with a progressive swelling on the right side of her face. Magnetic resonance imaging revealed a 5 × 5 cm lobulated parotid gland lesion, and fine needle aspiration biopsy was consistent with carcinoma. After informed consent, a Modified-Blair incision was given as a standard approach to the right preauricular area under general anaesthesia, and a right superficial parotidectomy with the removal of the tumor and selective lymph node dissection was performed. Histopathology of the resected mass was reported as parotid AciCC. She was given adjuvant radiation therapy. A repeat PET CT scan ten weeks after the completion of her adjuvant radiation treatment showed local disease recurrence as well as multiple pulmonary deposits. A repeat biopsy was reported as DOG-1 positive dedifferentiated (high-grade) acinic cell carcinoma, and she was offered platinum-based palliative systemic chemotherapy.

Clinical Discussion: Parotid acinic cell carcinomas with high-grade transformation are rare. This case highlights its critical diagnostic markers, curative and palliative management and long-term follow-up.

Conclusion: The transformation of parotid AciCC to high-grade, dedifferentiated pathology is unusual and belligerent. Hence, these tumors need intense treatment with a multimodality approach. Close follow-ups with history and physical examination, along with periodic imaging, should be considered for these patients.