Patient 2
A 64-year-old man was referred for right parotid swelling with facial
palsy (75/100: Sunnybrook method). Magnetic resonance imaging (MRI)
showed a mass (45 × 30 × 26 mm in size) in the right parotid gland with
suspected infiltration of the surrounding soft tissue and mandible.
Parotid carcinoma stage cT4aN0M0 was diagnosed, and extended
parotidectomy, ipsilateral selective neck dissection, facial nerve
reconstruction, and anterolateral thigh flap reconstruction were
performed. Histopathology of the resected tumor showed a salivary gland
carcinoma with biphasic appearance composed mainly of basaloid cells
with marked atypia (Fig. 2a). Immunostaining showed positivity for CK
AE1/AE3, CK7, p40, DOG1, and p63 (Fig. 2b, c). S-100 protein, α-smooth
muscle actin, vimentin, androgen receptor, HER2, CD56, chromogranin,
synaptophysin, and β-catenin were negatively stained. The Ki-67 LI was
approximately 70% in neoplastic cells. The differential diagnosis
included basal cell adenoma (BCA)/basal cell adenocarcinoma (BCAC) and
adenoid cystic carcinoma (ACC). Sanger sequencing revealed theHRAS Q61K mutation (no mutation in HRAS codons 12 and
13). Thus, the final diagnosis was EMC. Since histopathology
showed a high-grade carcinoma, we suspected EMC with high-grade
transformation. The postoperative course was uneventful. The patient was
disease-free at the 24-month follow-up.