Elsevier

Human Pathology

Volume 32, Issue 12, December 2001, Pages 1403-1407
Human Pathology

Case Studies
Dedifferentiation of adenoid cystic carcinoma: Report of a case implicating p53 gene mutation*

https://doi.org/10.1053/hupa.2001.28966Get rights and content

Abstract

Adenoid cystic carcinoma is an indolent tumour with an unfavorable long-term prognosis. Dedifferentiation of adenoid cystic carcinoma, which is associated with an accelerated clinical course, has recently been described. We report a case with immunohistochemical and molecular workup to elucidate the likely mechanism of dedifferentiation. The patient, a 64-year-old woman, developed dedifferentiated adenoid cystic carcinoma of the submandibular gland ab initio, accompanied by cervical lymph node metastasis. Histologically, the low-grade adenoid cystic carcinoma merged gradually into an extensive dedifferentiated component that was composed of solid sheets and cords of anaplastic tumor cells with focal gland formation. Immunohistochemically, the dedifferentiated component, but not the adenoid cyst carcinoma component, showed strong overexpression of p53 protein and cyclin D1, as well as a higher Ki67 index. Molecular study confirmed the presence of p53 gene mutation selectively in the dedifferentiated component, suggesting a pivotal role of p53 gene alteration in the dedifferentiation process of adenoid cystic carcinoma. HUM PATHOL 32:1403-1407. Copyright © 2001 by W.B. Saunders Company

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).

. In the submandibular gland, the low-grade adenoid cystic carcinoma is seen near the centre of the field (arrows). The dedifferentiated component occupies the rest of the infiltrative tumor. (Hematoxylin and eosin; original magnification ×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.

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