Parotid Oncocytoma as a Manifestation of Birt-Hogg-Dubé Syndrome

Abstract

Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disease characterized by skin fibrofolliculomas, pulmonary cysts, spontaneous pneumothoraces, and renal cancers. Oncocytomas are benign epithelial tumors that are also rare. Recently, there have been a few case reports of BHD with a parotid oncocytoma that appears to have a BHD phenotype. Here we document the eighth known case and describe the magnetic resonance imaging features of the parotid oncocytoma, which mimicked Warthin's tumor. Radiologists should be aware of the association between these rare disorders.

Figure 1

Magnetic resonance images of parotid oncocytoma. (a) T1-weighted imaging. (b) T2-weighted imaging. An axial magnetic resonance image shows a well-demarcated mass (white arrow) in the superficial and deep lobe of the right parotid gland. (c, d) The mass appears hyperintense to the native parotid gland tissue on fat-saturated T2-weighted imaging but hypointense on contrast-enhanced, fat-saturated T1-weighted imaging. (e, f) On diffusion-weighted images, the mass appeared hyperintense and hypointense according to the apparent diffusion coefficient.

Figure 2

Histopathologic findings of parotid clear cell oncocytoma. (a) A well-circumscribed, solid, mahogany-colored nodule. (b, c) Microscopically, fibrous encapsulated nodules containing oncocytic tumor cells with a clear cytoplasm. (hematoxylin-eosin staining; original magnification, 20× in (b) and 400× in (c))

Figure 3

Pulmonary computed tomography demonstrating a right pneumothorax and multiple cysts (arrow). An ellipsoidal cyst abuts on the proximal portion of the pulmonary artery.