Ossifying Parotid Carcinoma ex Pleomorphic Adenoma

Abstract

We present a unique case of an extensively ossified carcinoma ex pleomorphic adenoma (CXPA) in a 76-year-old man with a five-year history of a slowly growing parotid mass. Fine-needle aspiration of the mass was nondiagnostic. A computed tomography (CT) scan of the lesion revealed a well-circumscribed mass with peripheral calcification. Initial pathological analysis suggested a benign parotid mass, but rigorous decalcification revealed noninvasive CXPA. The patient underwent complete resection of the mass and remained disease-free nine months later. Extensive ossification of a seemingly benign parotid mass may mask areas of carcinoma that may progress if left untreated.

Figure 1

Computed tomography scan. (a) Axial and (b) coronal sections demonstrating a well-circumscribed, solid, isodense 4 × 3.5 cm mass with rim of peripheral calcification.

Figure 2

CXPA microscopic examination. (a) The benign myxoid component (top) is separated by a thick fibrous band from the malignant component (bottom). The neoplasm is composed of large cells with eosinophilic cytoplasm in a glandular pattern, H&E, 400x. (b) The well-circumscribed and encapsulated tumor shows areas of residual pleomorphic adenoma (lower right). A more cellular area (left) with irregular glandular architecture and composed of large cells with eosinophilic cytoplasm and pleomorphic nuclei is confined within the capsule, H&E, 400x. (c) The neoplasm is surrounded by a thin capsule (top) and cells show remarkable degree of cytological pleomorphism with hyperchromatic nuclei and prominent nucleoli, H&E, 400x. (d) The ossification comes from the periphery of the tumor within the capsule (left) and is present at the periphery of the benign components of the tumor (right), H&E, 100x.