Case StudiesDedifferentiation of adenoid cystic carcinoma: Report of a case implicating p53 gene mutation*
Section snippets
Case report
A 64-year-old woman presented with a 3-cm left submandibular mass, associated with pain, for 4 months. The mass was excised in conjunction with left functional neck dissection because of the presence of several palpable firm cervical lymph nodes in the neck. Postoperative radiotherapy was given. The patient was well at 6 months. She had a history of non–small-cell carcinoma of the left lung treated by chemotherapy and radiotherapy to the chest 7 years ago. There was no evidence of relapse of
Materials and methods
The excised tissue was fixed in 10% buffered formalin. After routine processing, 4-μm-thick sections were cut and stained with hematoxylin and eosin. Immunohistochemical studies were performed with an immunoperoxidase technique using the automated Ventana ES machine (Ventana, Tucson, Arizona). The antibodies used are summarized in Table 1.
For molecular analysis of the p53 gene, representative low-grade adenoid cystic carcinoma component and the dedifferentiated component were first identified
Histology
The tumor was infiltrative, with a central component of low-grade (grade 1 of 3) adenoid cystic carcinoma and a larger component of high-grade carcinoma (Fig 1).The latter occupied more than 80% of the tumor area.
The adenoid cystic carcinoma exhibited
Discussion
This reported case of salivary gland tumor shows gradual transition from low-grade adenoid cystic carcinoma with tubular and cribriform arrangement to a high-grade poorly differentiated adenocarcinoma with focal micropapillary and salivary duct carcinoma-like components. The gradual increase of cellular anaplasia and the preservation of myoepithelial cells in the tumor islands in the transitional zone support a process of dedifferentiation rather than the mere presence of collision tumors.
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Address correspondence and reprint requests to Dr Yuk-ping Chau, Department of Pathology, Queen Elizabeth Hospital, Wylie Road, Kowloon, Hong Kong.