[Analysis of basal cell adenoma of the parotid gland: nine cases report].

OBJECTIVE

To improve recognization of clinical, imaging and pathological characteristics of basal cell adenoma (BCA) of parotid gland.

METHOD

We collected and analyzed the data of the clinical manifestation, imaging features, histological and immunohistochemical characteristics of BCA of parotid gland (n = 9).

RESULTS

Among 9 patients, 2 male, 7 female, and the average age was 55.2 (from 34 to 66 years). The clinical manifestation showed the painless mass in the parotid region. Seven cases underwent CT and other 2 cases underwent MRI. Imaging showed all tumors were located in the superficial lobe, roughly spherical and non-lobulated in shape, with well-defined boundary. The maximal diameter was less than 30 mm. Seven cases showed slightly high density shadow of soft tissue on plain CT. Compared with the parotid signal intensity, two cases showed hypointensity on T1WI and high signal on T2WI. All lesions showed obvious enhancement on delayed contrast CT or MRI. Cystic changes occurred in two cases. Gross observation: the tumors were solid in section, grey, medium in nature and clear with the surrounding tissues. Cystic changes occurred in the superficial region of superficial lobe of two cases. The capsule of tumor was well circumscribed in 8 cases and focally involved in another case. Microscopy: The parenchyma of BCA was mainly composed of basaloid cells, with myoepithelial cells palisading at the periphery of the epithelial nests. Basal membrane separated the parenchyma from the stromal, the latter lacking the myxochondroid matrix. Immunohistochemistry: basaloid cells were positive for CKpan, CD117 and CKL, while myoepithelial cells were positive for P63, SMA, and calponin. The Ki-67 lablel ing index of tumour cell was 0-4%. All patients performed superficial lobe parotidectomy and tumor dissection, and they recovered well postoperatively without tumor recurrence or malignancy.

CONCLUSION

The BCA of parotid gland has distinctive imaging and pathological features with favourable postoperative prognosis.