Diagnosis and radiologic manifestations of malignant dumbbell tumors of the parotid gland: Review and 2 case reports

Primary malignant dumbbell tumors represent a special growth type of deep-lobe parotid neoplasm. Because they are located in an anatomically limited space between the skull base and the mandibular ramus, they do not cause any but a few nonspecific symptoms and may metastasize into the neck or distant organs before the primary tumor has ever been diagnosed. This article describes 2 cases that first presented as asymptomatic carcinoma unknown primary syndrome and were later discovered to be malignant dumbbell tumors of the parotid gland. Because adequate evaluation is essential for the subsequent management, several diagnostic methods available for the differential diagnosis of this tumor are discussed; we compare these according to their relevance to the therapeutic procedure. Magnetic resonance imaging was found to be the most appropriate imaging technique because of its ability to help us better differentiate between tumor and surrounding tissue. Computed tomography and single photon emission computed tomography can help us identify involvement of the skull base and mandibular ramus.