Immunohistochemical study of adenoid cystic carcinoma in the head and neck

Localization of keratin, S-100 protein and lysozyme and cellular differentiation

Abstract

Adenoid cystic carcinoma (ACC) is a specific variant of adenocarcinma with a characteristic cribriform structure. ACC may arise from salivary glands and various other sites, but the origin and cellular composition of various structures in ACC is controversial.
In this study immunohistochemical localization of keratin, S-100 protein, and lysozymes was evaluated for five fundamental structures (tubular, cribriform, trabecular, reticular, and solid) of 60 adenoid cystic carcinomas arising in the head and neck. Furthermore, the correlation among arising sites and the histological grading of ACC and the immunohistochemical positive classification (IPC) were investigated.
IPC was classified into 3 degrees according to staining of keratin antibody. S-100 protein antibody, and lysozyme antibody, respectively.
Tubular structures composed of single tumor cell rows were positive for both keratin and S-100 protein stainings. These tubular structures resembled intercalated ducts of normal salivary galnds.
Tubular structures composed of two irregular tumor cell rows consisted of a mixture of keratin-positive cuboidal cells and S-100-protein-positive triangular or polygonal cells. These tubular structures may also resemble intercalated ducts. Tubular structures composed of two regular tumor cell rows consisted of keratin-positive and S-100-protein-negative luminal cells and keratin-negative and S-100-protein-negative nonluminal cells. These structures may there fore resemble interlobular ducts.
In cribriform structures, cells lining cyst-like spaces showed both keratin and S-100-protein-negative staining; nonlining cells positive for both keratin and S-100 protein composed small tubules. In trabecular structures, inner tumor cells were keratin-positive and S-100-protein-negative, but the converse was true for outer tumor cells. Reticular structures may result from a reduction in tumor cells accompanied by an increase in cyst-like spaces in cribriform structures. Keratin-positive and/or S-100-protein-positive tumor cells were scattered in solid structures, but these tumor cells were not typically arranged.
The IPC of keratin showed a correlation between stongly positive degree and histological Grade, but no correlation between positive degree and the arising site. The IPC of S-100 protein indicated no correlaton between positive degree and the arising site. The immunohistochemical positive rate of lysozymes was 11.7%(7/60), but only one strongly positve case was noted. In ACC there were few tumor cells which had differentiated to the point of secreting lysozymes. There was no lysozyme-positive-case in ACC originating from the nasal and antral mucosa, lacrimal gland, external auditory canal, and skin.