A 68-year-old male, diabetic with a forty pack-year smoking history presented with an enlarging left, slightly tender, rapidly progressive swelling of the left parotid gland during the previous 6 months before our first examination. The patient was referred to head and neck clinic, Department of Otolaryngology Head and Neck Surgery, Ziv Medical Center in Safed, in the north of Israel.
Physical examination showed a firm, immobile, slightly tender, 3 × 3 cm left parotid mass with overlying skin change (Fig. 1), with multiple hard, immobile lymph nodes, 3 * 2 cm, at level II,III,V of the left neck, the remainder of the head and neck examination was unremarkable. Flexible nasendoscopy findings of the nasopharynx, oropharynx, and larynx were unremarkable.
Fine needle aspiration (FNA) of the left parotid mass was consistent with positive malignant cells for high grade mucoepidermoid carcinoma with mitosis.
Contrast-enhanced magnetic resonance imaging (MRI) revealed a lobulated, irregular mass, 37*39*47 mm located in the posteroinferior segment of the superficial and deep lobe in the left parotid gland, with areas of extensive central necrosis, septation, and peripheral wall enhancement contiguous with the anterior portion of external auditory canal and SCM muscle with subcutaneous tissue and skin involvement, several nodules in the left infraparotid area and level II were calcified (Fig. 2).
The 18F-FDG PET/CT revealed hypermetabolic activity within the mass in the left parotid gland with involvement of the skin, SCM muscle and several nodules in the left infraparotid area and level II,III in the left neck (Fig. 3).
The final diagnosis was clinical stage IV (T4aN2bM0).
The patient was considered as high-grade MECs which progressed rapidly and caused pain, soft tissue invasion; these MECs are associated with poor overall survival, which approaches 40–50% at 5 years, and with an increased risk for locoregional and distant failures17,18,19 .
The recommended therapy for high-grade MECs includes surgical resection with selective neck dissection followed by adjuvant radiotherapy 20.
In our case, the high morbidity and mortality associated with the need of extensive surgical resection with free flap reconstruction and the massive loss of tissue with possible facial nerve sacrifice, in addition to increased risk for locoregional and distant failures led us to think about neoadjuvant treatment.
Pembrolizumab monotherapy was generally well tolerated in advanced Salivary Gland Carcinoma (SGC), with a safety profile that reflects previous experience of pembrolizumab in patients with advanced cancers21.
Treatment plan was made by a multidisciplinary team and after multiple discussions with the goal of maximizing survival with preservation of form and function.
Our patient received pembrolizumab intravenously at 200 mg every 2 weeks, with a good compliance.
From September 2021 to November 2021, he underwent 2 cycles of pembrolizumab with no side effects.
The MRI scan after 3 cycles revealed a significant decrease in the tumor or even its disappearance and on follow-up, the patient had attained a complete remission in the clinic examination (Fig. 4,5).
Restaging with 18FDG PET-CT at 6 weeks after completion of immunologic treatment demonstrated a full resolution of the parotid gland metabolic activity. In the left neck, the nodal status had generally improved with no signs of hypermetabolic activity. High metabolic uptake was not seen elsewhere. (Fig. 6 ).
As a precaution, left parotidectomy and unilateral neck dissection levels I,II,III,IV were recommended for locoregional control and because of remaining morphological masses on ct. (Fig. 7).
All the 18FDG PET-CT scans performed are summarized in (Fig. 8).
Final pathological results showed no evidence of carcinoma neither in the parotid gland nor in the neck lymph nodes and had free margins .
The patient has continued to be supervised with CT scans and serum tumor marker measurements every 3 or 4 months and is still in complete remission at this time.