Clinical presentation[ edit ] The tumor is usually solitary and presents as a slow growing, painless, firm single nodular mass. Isolated nodules are generally outgrowths of the main nodule rather than a multinodular presentation. It is usually mobile unless found in the palate and can cause atrophy of the mandibular ramus when located in the parotid gland. When found in the parotid tail, it may present as an eversion of the ear lobe.
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The oncogenic simian virus SV40 may play a role in onset or progression and prior head and neck irradiation is a risk factor for the development of these tumors 13, Clinical presentation Patients typically present with a smooth, painless, enlarging mass.
Pathology As the name suggests, pleomorphic adenomas are composed of a mixture of variable histology. They contain both epithelial and myoepithelial mesenchymal tissues, with mixed histology. They appear encapsulated and well circumscribed however the pseudocapsule is delicate and incomplete with microscopic extensions reaching beyond it, accounting for the high risk of recurrence when these tumors are enucleated see below 5,6.
The gross appearance depends upon the relative proportion of epithelial elements and a stromal component which may range from myxoid to cartilage. Tumors with a prominent cartilaginous matrix have a bluish-grey opalescent appearance. Three histological types have been described: myxoid hypocellular : most common, highest rate of recurrence cellular classic Radiographic features On all modalities, these tumors typically appear as rounded masses with well-defined, "bosselated" or "polylobulated" borders many small undulations, not truly lobulated.
They are most commonly located within the parotid gland, particularly the superficial lobe. Pleomorphic adenomas can also arise from salivary rest cells in the parapharyngeal space itself without connection to the parotid gland. Ultrasound They are typically hypoechoic and may show posterior acoustic enhancement.
Ultrasound is also useful in guiding a biopsy both FNAC and core biopsies but needs to be carried out with care to avoid facial nerve damage 8,9.
CT When small, they have homogeneous attenuation and prominent enhancement. When larger, they can be heterogeneous with less prominent enhancement, foci of necrosis, and possible delayed enhancement. Small regions of calcification are common 1, MRI The signal characteristics are homogeneous when the tumor is small. Larger tumors may be heterogeneous.
Adenoma Pleomorfo: tumore parotideo frequente e particolare
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