KCP 794 인하대병원 전공의 최창환

Clinical history M/49 6개월 전부터 만져지는 오른쪽 귀 앞부위의 종괴 경부 컴퓨터 단층촬영 오른쪽 귀밑샘의 얕은엽에 4.1cm의 경계가 좋은 불균질하게 조영증강되는 종괴 세침흡인 검사 후 절제술 시행

Well-marginated heterogeneous enhancing mass (4.1x3.6x2.8cm) Benign salivary gland tumor such as pleomorphic adenoma, more likely R/O low grade malignant salivary gland tumor

Cytologic findings Cellular smear Isolated and aggregates of bland-looking myoepithelial cells in myxoid background Scattered clusters of atypical epithelial cells large hyperchromatic nuclei, prominent nucleoli and irregular nuclear membrane abundant cytoplasm with focal finely granular/vacuolated cytoplasm

Differential diagnosis Malignant salivary gland tumor Carcinoma ex pleomorphic adenoma Adenocarcinoma, NOS Salivary duct carcinoma Acinic cell carcinoma Mucoepidermoid carcinoma

Cytologic diagnosis Parotid gland, right, FNA: Carcinoma ex pleomorphic adenoma

Histologic diagnosis NONINVASIVE CARCINOMA EX PLEOMORPHIC ADENOMA Parotid gland, right near total parotidectomy: NONINVASIVE CARCINOMA EX PLEOMORPHIC ADENOMA with 1) Carcinoma component: ADENOCARCINOMA, not otherwise specified 2) Tumor size: 4.0x3.3cm 3) Carcinoma size: 2.1x1.6cm 4) Confinement to the capsule without invasion

Carcinoma ex pleomorphic adenoma Adenocarcinoma, NOS Salivary duct carcinoma Mucoepidermoid carcinoma Adenoid cystic carcinoma Acinic cell carcinoma Clear cell carcinoma Myoepithelial carcinoma Carcinoma component >50% of mass in 80% cases (Olsen et al) >66% of mass in 42% cases (Zbaren et al) Any form of carcinoma

Diagnostic pitfall Sampling error Benign component alone Carcinomatous element alone

Diagnostic pitfall Nigam et al. 2004 Group I Group II Unequivocal malignant cells Benign epithelial and stromal components of pleomorphic adenoma Group II Mild to moderate degrees of pleomorphism Absence of unequivocal malignant cell Benign epithelial and stromal components Sampling error is an important cause of diagnostic pitfalls

Identifying CXPA by FNAC 4/14 (28%) (Nouraei et al) 13/26 (50%) (Klijanienko et al) 7/16 (43%) (Zbaren et al) Most false-negative finding Pleomorphic adenoma Sampling error > misinterpretation Small carcinoma component Other malignancy Acinic cell carcinoma (Verma et al)

Diagnostic clue Background benign component Carcinomatous element Fibrillary/chondromyxoid background matrix Ovoid/plasmacytoid myoepithelial cells Uniform epithelial cells Carcinomatous element Any form of carcinoma