Epithelial-myoepithelial carcinoma of salivary gland

These are uncommon low grade carcinomas of salivary glands are composed in varying portions of ductal cells and clear myoepithelial cells. They constituted 1.1% of all epithelial salivary gland tumours reviewed by the AFIP².

Clinical features

This is usually a tumour of the parotid gland⁴. Rare sites include submandibular gland¹⁰, sinonasal tract^5,8, larynx⁹, trachea, bronchus⁷ and lung⁶ , breast and lacrimal gland.

Macroscopic appearance

The tumour is well circumscribed. It is usually grey-white to tan-white. Haemorrhage and necrosis are uncommon. Some tumours are cystic.

Histopathology

There is a dual population of ductal and myoepithelial cells. In some cases, the ductal component is sparse⁴. The ductal cells have eosinophilic cytoplasm and uniform round nuclei. The ducts may contain PAS-positive, mucicarmine-negative eosinophilic proteinaceous material. The ductal cells are surrounded by large polygonal clear cells containing large amounts of glycogen. The clear cells may sometimes by spindled. Aggregates of cells are often surrounded by hyalinised basement membrane, giving an organoid pattern. When cysts are present, papillary epithelial projections into the cysts are seen. Perineural invasion is occasionally seen⁴.

Immunohistochemistry

	ductal cells	clear cells
cytokeratin	strongly positive	weakly positive
S-100	variable2	variable2
Calponin	negative	variable, may be intense
actin	negative	variable
GFAP		may be positive
myosin		may be positive
vimentin		may be positive

Ultrastructure

Confirms the dual population¹² with a myoepithelial cell component¹¹.

Differential diagnosis

• Pleomorphic adenoma: shows myxochondroid stroma not seen in epithelial-myoepithelial tumours. The myoepithelial cells are not large and optically clear.

• Hyalinising clear cell carcinoma: occurs in minor salivary glands and lacks ductal or myoepithelial differentiation

• Mucoepidermoid carcinoma: lacks a biphasic pattern

• Acinic cell tumour: lacks a biphasic pattern

• Oncocytoma: lacks a biphasic pattern

• Metastatic renal cell carcinoma: lacks a biphasic pattern

Prognosis

There is a 30-50% local recurrence rate^3,4. Metastases to local lymph nodes are seen n 18% of cases and distal metastases to lung, kidney and brain in 8% of cases, resulting in a similar mortality rate. Recurrence and metastases may occur more than 20 years after first presentation. Nuclear atypia in more than 20% of cells³ and aneuploidy³ may indicate a worse prognosis.

References

Diagnostic histopathology of tumors. Edited by CDM Fletcher. 2nd edition. Churchill Livingstone. Page 277.

¹Perez-Ordonez B. Selected topics in salivary gland tumour pathology. Current Diagnostic Pathology 2003;9:355-365.

²Eliis GL, Auclair PL. Malignant epithelial tumours in: Tumors of the Salivary Glands. Armed Forces Institute of Pathology, Washington DC. Atlas of Tumor Pathology, 3rd Edition, 1996;15-373.

³Fonseca, I. and J. Soares (1993). "Epithelial-myoepithelial carcinoma of the salivary glands. A study of 22 cases." Virchows Arch A Pathol Anat Histopathol 422(5): 389-96.

⁴Brocheriou, C., M. Auriol, et al. (1991). "[Epithelial-myoepithelial carcinoma of the salivary glands. Study of 15 cases and review of the literature]." Ann Pathol 11(5-6): 316-25.

⁵Harada, H., S. I. Kashiwagi, et al. (1996). "Epithelial-myoepithelial carcinoma--report of a case arising in the nasal cavity." J Laryngol Otol 110(4): 397-400.

⁶Wilson, R. W. and C. A. Moran (1997). "Epithelial-myoepithelial carcinoma of the lung: immunohistochemical and ultrastructural observations and review of the literature." Hum Pathol 28(5): 631-5.

⁷Ryska, A., Z. Kerekes, et al. (1998). "Epithelial-myoepithelial carcinoma of the bronchus." Pathol Res Pract 194(6): 431-5; discussion 436-8.

⁸Jin, X. L., C. N. Ding, et al. (1999). "Epithelial-myoepithelial carcinoma arising in the nasal cavity: a case report and review of literature." Pathology 31(2): 148-51.

⁹Mikaelian, D. O., R. B. Contrucci, et al. (1986). "Epithelial-myoepithelial carcinoma of the subglottic region: a case presentation and review of the literature." Otolaryngol Head Neck Surg 95(1): 104-6.

¹⁰Simpson, R. H., T. J. Clarke, et al. (1991). "Epithelial-myoepithelial carcinoma of salivary glands." J Clin Pathol 44(5): 419-23.

¹¹Luna, M. A., N. G. Ordonez, et al. (1985). "Salivary epithelial-myoepithelial carcinomas of intercalated ducts: a clinical, electron microscopic, and immunocytochemical study." Oral Surg Oral Med Oral Pathol 59(5): 482-90.

¹²Corio, R. L., J. J. Sciubba, et al. (1982). "Epithelial-myoepithelial carcinoma of intercalated duct origin. A clinicopathologic and ultrastructural assessment of sixteen cases." Oral Surg Oral Med Oral Pathol 53(3): 280-7.

This page last revised 1.2.2004.

©SMUHT/PW Bishop