Basaloid Tumors of the Salivary Glands

Background

These are rare and probably a heterogenous group of tumors arising within the salivary glands. Only the pathologist can issue the correct diagnosis with a characteristic histology of small basaloid cells. The difficulty for the pathologists lies in differentiating this tumor from other salivary gland tumors which it closely resembles.

OUTLINE

Epidemiology

Gross Appearance and Clinical Variants

Histopathological Features and Variants

Special Stains/Immunohistochemistry/Electron Microscopy

Differential Diagnosis

Prognosis and Treatment

Commonly Used Terms

Internet Links

EPIDEMIOLOGY CHARACTERIZATION

SYNONYMS

INCIDENCE <1% of all salivary gland tumors

AGE Seventh decade

SEX About equal

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

GENERAL

Basal cell adenoma-an unusual presentation.

Hemachandran M, Lal A, Vaiphei K.

Ann Diagn Pathol. 2003 Oct;7(5):292-5 Abstract quote.

Basal cell adenoma is an uncommon epithelial neoplasm of the salivary gland most commonly arising in the parotid glands. We report a case of basal cell adenoma of the minor salivary gland presenting as a slowly progressing, large parapharyngeal mass.

Histopathology revealed a well-encapsulated mass with characteristic histomorphology. Immunohistochemistry showed selective positivity for pancytokeratin, S-100, and smooth muscle actin in the tumor which highlighted the participation of myoepithelial cells in histogenesis. In addition, positivity was noted for carcinoembryonic antigen and vimentin. Ultrastructural analysis showed characteristic features including reduplicated basal laminae around the tumor cells, presence of intermediary filaments, and rough endoplasmic reticulum in the cytoplasm.

There are no reports of basal cell adenoma presenting as a parapharyngeal mass lesion in the available English literature. This case highlights the rarity of this tumor with regard to its site of origin, possibly from a minor salivary gland.

Basal cell adenocarcinoma of minor salivary and seromucous glands of the head and neck region.

Fonseca I, Soares J.

Departamento de Patologia Morfologica, Instituto Portuges de Oncologia de Francisco Gentil, Lisboa, Portugal.

Semin Diagn Pathol 1996 May;13(2):128-37 Abstract quote
Basal cell adenocarcinoma of salivary glands is an uncommon and recently described entity occurring almost exclusively at the major salivary glands.

This report provides an overview of the clinicopathologic profile of this neoplasm by including the personal experience on the clinical features, microscopic and ultrastructural characteristics, proliferation activity, and DNA tumor patterns of 12 lesions occurring at the minor salivary glands of the head and neck region, where basal cell adenocarcinoma is probably an underecognized entity, previously reported under different designations.

Basal cell adenocarcinoma predominates at the seventh decade without sex preference. The tumors affecting the minor salivary glands occur most frequently at the oral cavity (jugal mucosa, palate) and the upper respiratory tract. The prevalent histologic tumor pattern is represented by solid neoplastic aggregates with a peripheral cell palisading arrangement frequently delineated by basement membrane-like material. The neoplastic clusters are formed by two cell populations: the small dark cell type (that predominates) and a large cell type. Necrosis, either of the comedo or the apoptotic type, is a frequent finding. Perineural growth occurs in 50% of the cases and vascular permeation in 25%. Immunohistochemistry identifies a dual differentiation with a reactivity pattern indicative of ductal epithelial and myoepithelial differentiation, which can be confirmed by electron microscopy.

The differential diagnosis of the neoplasm includes its benign counterpart, the basal cell adenoma, solid variant of adenoid cystic carcinoma, undifferentiated carcinoma, and basaloid squamous carcinoma. The tumors recur more frequently than lesions originating in major salivary glands. Mortality is associated with the anatomic site of the lesion, advanced stage, residual neoplasia at surgery, and tumor recurrence.

The importance of recognizing basal cell adenocarcinoma outside major salivary glands is related to the clinical behavior of the neoplasm that seems to be less indolent than that of tumors arising in major salivary glands.

HISTOLOGICAL TYPES CHARACTERIZATION

GENERAL

Basaloid tumors of the salivary glands.

Chhieng DC, Paulino AF.

Department of Pathology, University of Alabama at Birmingham, AL; and the Department of Pathology, University of Michigan Hospitals, Ann Arbor, MI.

Ann Diagn Pathol 2002 Dec;6(6):364-72 Abstract quote
Basaloid tumors of the salivary glands are a heterogeneous group of benign and malignant lesions characterized by small tumor cells with round or ovoid nuclei surrounded by a thin rim of cytoplasm.

Primary salivary gland tumors with this predominant morphology include basal cell adenoma, basal cell adenocarcinoma, cellular pleomorphic adenoma, adenoid cystic carcinoma, and small cell undifferentiated carcinoma. Certain metastatic lesions and nonepithelial neoplasms can also demonstrate a basaloid appearance.

Histologic diagnosis based on resected tumors is usually straightforward when the architecture can be adequately assessed. However, in limited biopsies and particularly in cytologic samples, the evaluation can be quite challenging. A systematic approach aided by immunohistochemistry is essential to arrive at an accurate diagnosis.

Comparative cytologic and histologic study of fifteen salivary basal-cell tumors: differential diagnostic considerations.

Klijanienko J, el-Naggar AK, Vielh P.

Departement de Pathologie, Institut Curie, Paris, France.
Diagn Cytopathol 1999 Jul;21(1):30-4 Abstract quote
Cytologic results of preoperative fine-needle sampling (FNS) of 15 salivary basal-cell tumors are presented, described, and compared with histologic results.

Eleven of the FNAS showed individual and clusters of homogeneous basaloid cells with scanty cytoplasm, occasional peripheral palisading, and naked nuclei and were diagnosed as basal-cell adenoma. Four samples showed, in addition, three-dimensional cell clusters with mild cytonuclear atypia, occasional mitosis, and/or focal necrosis and were diagnosed as basal-cell adenocarcinoma.

Basal-cell tumors must be diagnostically differentiated from adenoid cystic carcinoma and metastatic basal-cell carcinoma. Although the adenomas diagnosed by cytologic examination and four suspected carcinomas in our series were verified by histologic testing, the bland cytologic features of basal-cell adenocarcinoma may not always allow diagnosis on cytologic examination.

Membranous basal cell adenoma of the salivary gland: a clinicopathologic study of 12 cases.

Yu GY, Ubmuller J, Donath K.

Department of Oral and Maxillofacial Surgery, Beijing Medical University, China.

Acta Otolaryngol 1998 Jul;118(4):588-93 Abstract quote
Twelve cases with membranous basal cell adenoma of the salivary gland were analysed clinicopathologically. Its histology was characterized by palisading of peripheral cells and an excessive hyaline basal membrane.

The differential diagnosis involved the solid variant of basal cell adenoma, basal cell adenocarcinoma, solid subtype of adenoid cystic carcinoma and basaloid squamous cell carcinoma. Four cases had coexisting dermal cylindromas of the scalp. Screening for skin lesions of the scalp or other locations is suggested. In 8 cases, the tumors demonstrated multifocal origin. Total parotidectomy rather than superficial parotidectomy is suggested to avoid the recurrence of the tumor.

One case showed malignant transformation and cervical lymph node metastases. A close follow-up after treatment is necessary.

VARIANTS

MYOEPITHELIOMA FEATURES

Basal cell adenoma with myoepithelial cell-derived "stroma": a new major salivary gland tumor entity.

Dardick I, Daley TD, van Nostrand AW.
Head Neck Surg 1986 Mar-Apr;8(4):257-67 Abstract quote
The light microscopic, immunohistochemical, and ultrastructural features of a unique variant of tubular-trabecular basal cell adenoma are described.

The unusual feature of the six examples reported is the richly cellular "stroma" composed of spindle cells coursing between the anastomosing cords of epithelial tumor cells. Immunohistochemistry of all six cases and electron microscopy of two examples illustrated the biphasic differentiation of the epithelial portion of this form of basal cell adenoma, with a central core of duct luminal cells bordered on either side by one or more layers of modified myoepithelial cells.

By light microscopy, the features and arrangement of cells in "stromal" regions of this tumor convey a fibroblastic derivation. However, this population of cells stains strongly for S-100 protein, ultrastructurally displays excessive external lamina production, intercellular junctions, and a growth pattern unlike fibroblasts, and is involved in the formation of extracellular mucinous materials. Such aspects indicate a second population of neoplastic myoepithelial cells in this tumor.

Thus, this form of tubular-trabecular basal cell adenoma displays tricellular differentiation and, perhaps, may be considered either a hybrid basal cell adenoma and myoepithelioma or a cellular pleomorphic adenoma.

SPECIAL STAINS/IMMUNOPEROXIDASE/
OTHER CHARACTERIZATION

SPECIAL STAINS

IMMUNOPEROXIDASE

Immunohistochemical analysis of basal cell adenocarcinoma.

Williams SB, Ellis GL, Auclair PL.

Department of Oral Pathology, Armed Forces Institute of Pathology, Washington, D.C.
Oral Surg Oral Med Oral Pathol 1993 Jan;75(1):64-9 Abstract quote
Basal cell adenocarcinoma is a recently defined category of salivary gland neoplasms. As the terminology implies, this group of tumors has many histopathologic features that are similar to the more well-known basal cell adenomas.

To better characterize these tumors, 23 basal cell adenocarcinomas were reviewed and compared with 11 basal cell adenomas with the use of light microscopic and immunohistochemical methods.

Evaluation of cytokeratin, S-100 protein, glial fibrillary acidic protein, carcinoembryonic antigen, epithelial membrane antigen, smooth muscle actin, vimentin, B72.3, Ber-EP4, and milk fat globulin immunoreactivity was performed. Parallel to the morphologic similarity, the immunoprofiles of the basal cell adenocarcinoma and basal cell adenoma were quite similar. Both tumors showed reactivity patterns indicative of ductal epithelial and myoepithelial differentiation. In addition, reactivity to some polymorphic epithelial mucins was observed, which suggested glandular differentiation. The identification of antigens found normally in myoepithelial and epithelial cells supports the concept that these tumors are derived from pluripotential salivary gland epithelial cells.

The comparable immunohistochemical profiles imply evolvement from similar cell lines and lead us to conclude that distinction between the two is not possible on the basis of these findings.

ELECTRON MICROSCOPY

Basal cell adenocarcinoma of the salivary gland: an ultrastructural and immunohistochemical study.

Quddus MR, Henley JD, Affify AM, Dardick I, Gnepp DR.

Rhode Island Hospital and Brown University School of Medicine, Providence 02903, USA.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999 Apr;87(4):485-92 Abstract quote
OBJECTIVE: The purpose of this study was to examine the ultrastructural and immunohistochemical characteristics of basal cell adenocarcinoma.

STUDY DESIGN: Three cases of basal cell adenocarcinoma of the salivary glands were studied by means of light microscopy, electron microscopy, and immunohistochemistry.

RESULTS: Some of the architectural tumor patterns encountered were solid, some were trabecular, and some were mixed. Ultrastructurally, solid areas were composed of nonluminal cells, some of which contained tonofilaments and well-formed desmosomes; tubulo-trabecular areas differentiated into both luminal and nonluminal cells. Both growth patterns were associated with the formation of excess basal lamina, marginally and between nonluminal cells. Myofilaments were infrequent in nonluminal cells of solid or trabecular areas. Cytokeratin (AE1/AE3) stained all 3 tumors, more peripherally in the solid pattern and usually centrally in the trabecular areas; vimentin stained all 3 tumors diffusely; smooth muscle actin (IA4) stained all 3 tumors but was mainly confined to peripheral tumor cells in both the solid and the trabecular growth patterns; epithelial membrane antigen and carcinoembryonic antigen stained 1 of the 3 tumors, predominantly in the luminal cells; p53 oncoprotein was focally positive in 2 of the 3 tumors; Ki-67 stained less than 5% of the tumor cells in all cases; and c-erb-B2 was uniformly negative in all cases. Staining patterns of cytokeratin and actin varied with the architecture of the tumor.

CONCLUSIONS: Neither ultrastructural characteristics nor immunohistochemistry findings appear to distinguish basal cell adenocarcinoma from basal cell adenoma.

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

ADENDOID CYSTIC CARCINOMA

BASAL CELL CARCINOMA-METASTATIC

PLEOMORPHIC ADENOMA With predominant basaloid pattern

PROGNOSIS AND TREATMENT CHARACTERIZATION

PROGNOSTIC FACTORS

GENERAL

Basal cell adenocarcinoma of the salivary glands: comparison with basal cell adenoma through assessment of cell proliferation, apoptosis, and expression of p53 and bcl-2.

Nagao T, Sugano I, Ishida Y, Hasegawa M, Matsuzaki O, Konno A, Kondo Y, Nagao K.

Department of Surgical Pathology, Teikyo University, School of Medicine, Ichihara Hospital, Chiba, Japan.

Cancer 1998 Feb 1;82(3):439-47 Abstract quote
BACKGROUND: Basal cell adenocarcinoma (BCAC) of the salivary gland is a rare tumor and recently described entity. Eleven cases of BCAC are presented here and compared with basal cell adenoma (BCA) through assessment of cell proliferative activity, apoptosis, and expression of p53, bcl-2, and epidermal growth factor receptor (EGFR) because these two tumors show close similarity in some cytologic and architectural characteristics.

METHODS: Formalin fixed, paraffin embedded sections of 11 cases of BCAC and 9 cases of BCA, selected from the authors' files of 1851 primary tumors of the major salivary gland, were examined using immunostaining for Ki-67 (MIB-1), p53, bcl-2, and EGFR. In addition, apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling.

RESULTS: The incidence of BCAC was 0.6% among patients with major salivary gland tumors in the current series. Nine cases of BCAC arose in the parotid gland and two were of submandibular gland origin. Approximately 50% of the patients had recurrences, but no patient developed metastases or died of disease. Vascular involvement (75%), perineural invasion (36%), and necrosis (45%) were common features. Cell proliferative activity, including mitotic count, Ki-67 labeling index (LI), and apoptotic index were significantly higher in BCAC than BCA. More than four mitotic figures per ten high-power fields or a Ki-67 LI > 5% appeared to be limited to cases of BCAC. Considering those cases expressing p53 or EGFR in > 10% of tumor cells as positive, 6 of the 11 BCAC cases were positive for p53 and 3 were positive for EGFR. In contrast, all BCA cases were negative for p53 and EGFR. Although all cases of BCA were strongly positive for bcl-2 (> 50% of tumor cells), 3 of 11 cases of BCAC were completely negative.

CONCLUSIONS: BCAC is a rare salivary gland tumor with a relatively high recurrence rate. Examination of cell proliferation, apoptosis, and expression of p53, bcl-2, and EGFR were found to be useful in distinguishing malignant basal cell tumors from their benign counterparts arising in the salivary gland.

TREATMENT

SURGERY Complete removal

Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Eight Edition. Mosby 1996.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Robbins Pathologic Basis of Disease. Sixth Edition. WB Saunders 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.

Commonly Used Terms

Salivary Gland

Basic Principles of Disease
Learn the basic disease classifications of cancers, infections, and inflammation

Commonly Used Terms
This is a glossary of terms often found in a pathology report.

Diagnostic Process
Learn how a pathologist makes a diagnosis using a microscope

Surgical Pathology Report
Examine an actual biopsy report to understand what each section means

Special Stains
Understand the tools the pathologist utilizes to aid in the diagnosis

How Accurate is My Report?
Pathologists actively oversee every area of the laboratory to ensure your report is accurate

Got Path?
Recent teaching cases and lectures presented in conferences

Internet Links

Last Updated 11/3/2003

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL
Basaloid tumors of the salivary glands. Chhieng DC, Paulino AF. Department of Pathology, University of Alabama at Birmingham, AL; and the Department of Pathology, University of Michigan Hospitals, Ann Arbor, MI.	Ann Diagn Pathol 2002 Dec;6(6):364-72 Abstract quote Basaloid tumors of the salivary glands are a heterogeneous group of benign and malignant lesions characterized by small tumor cells with round or ovoid nuclei surrounded by a thin rim of cytoplasm. Primary salivary gland tumors with this predominant morphology include basal cell adenoma, basal cell adenocarcinoma, cellular pleomorphic adenoma, adenoid cystic carcinoma, and small cell undifferentiated carcinoma. Certain metastatic lesions and nonepithelial neoplasms can also demonstrate a basaloid appearance. Histologic diagnosis based on resected tumors is usually straightforward when the architecture can be adequately assessed. However, in limited biopsies and particularly in cytologic samples, the evaluation can be quite challenging. A systematic approach aided by immunohistochemistry is essential to arrive at an accurate diagnosis.
Comparative cytologic and histologic study of fifteen salivary basal-cell tumors: differential diagnostic considerations. Klijanienko J, el-Naggar AK, Vielh P. Departement de Pathologie, Institut Curie, Paris, France.	Diagn Cytopathol 1999 Jul;21(1):30-4 Abstract quote Cytologic results of preoperative fine-needle sampling (FNS) of 15 salivary basal-cell tumors are presented, described, and compared with histologic results. Eleven of the FNAS showed individual and clusters of homogeneous basaloid cells with scanty cytoplasm, occasional peripheral palisading, and naked nuclei and were diagnosed as basal-cell adenoma. Four samples showed, in addition, three-dimensional cell clusters with mild cytonuclear atypia, occasional mitosis, and/or focal necrosis and were diagnosed as basal-cell adenocarcinoma. Basal-cell tumors must be diagnostically differentiated from adenoid cystic carcinoma and metastatic basal-cell carcinoma. Although the adenomas diagnosed by cytologic examination and four suspected carcinomas in our series were verified by histologic testing, the bland cytologic features of basal-cell adenocarcinoma may not always allow diagnosis on cytologic examination.
Membranous basal cell adenoma of the salivary gland: a clinicopathologic study of 12 cases. Yu GY, Ubmuller J, Donath K. Department of Oral and Maxillofacial Surgery, Beijing Medical University, China.	Acta Otolaryngol 1998 Jul;118(4):588-93 Abstract quote Twelve cases with membranous basal cell adenoma of the salivary gland were analysed clinicopathologically. Its histology was characterized by palisading of peripheral cells and an excessive hyaline basal membrane. The differential diagnosis involved the solid variant of basal cell adenoma, basal cell adenocarcinoma, solid subtype of adenoid cystic carcinoma and basaloid squamous cell carcinoma. Four cases had coexisting dermal cylindromas of the scalp. Screening for skin lesions of the scalp or other locations is suggested. In 8 cases, the tumors demonstrated multifocal origin. Total parotidectomy rather than superficial parotidectomy is suggested to avoid the recurrence of the tumor. One case showed malignant transformation and cervical lymph node metastases. A close follow-up after treatment is necessary.
VARIANTS
MYOEPITHELIOMA FEATURES
Basal cell adenoma with myoepithelial cell-derived "stroma": a new major salivary gland tumor entity. Dardick I, Daley TD, van Nostrand AW.	Head Neck Surg 1986 Mar-Apr;8(4):257-67 Abstract quote The light microscopic, immunohistochemical, and ultrastructural features of a unique variant of tubular-trabecular basal cell adenoma are described. The unusual feature of the six examples reported is the richly cellular "stroma" composed of spindle cells coursing between the anastomosing cords of epithelial tumor cells. Immunohistochemistry of all six cases and electron microscopy of two examples illustrated the biphasic differentiation of the epithelial portion of this form of basal cell adenoma, with a central core of duct luminal cells bordered on either side by one or more layers of modified myoepithelial cells. By light microscopy, the features and arrangement of cells in "stromal" regions of this tumor convey a fibroblastic derivation. However, this population of cells stains strongly for S-100 protein, ultrastructurally displays excessive external lamina production, intercellular junctions, and a growth pattern unlike fibroblasts, and is involved in the formation of extracellular mucinous materials. Such aspects indicate a second population of neoplastic myoepithelial cells in this tumor. Thus, this form of tubular-trabecular basal cell adenoma displays tricellular differentiation and, perhaps, may be considered either a hybrid basal cell adenoma and myoepithelioma or a cellular pleomorphic adenoma.

SPECIAL STAINS/IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
SPECIAL STAINS
IMMUNOPEROXIDASE
Immunohistochemical analysis of basal cell adenocarcinoma. Williams SB, Ellis GL, Auclair PL. Department of Oral Pathology, Armed Forces Institute of Pathology, Washington, D.C.	Oral Surg Oral Med Oral Pathol 1993 Jan;75(1):64-9 Abstract quote Basal cell adenocarcinoma is a recently defined category of salivary gland neoplasms. As the terminology implies, this group of tumors has many histopathologic features that are similar to the more well-known basal cell adenomas. To better characterize these tumors, 23 basal cell adenocarcinomas were reviewed and compared with 11 basal cell adenomas with the use of light microscopic and immunohistochemical methods. Evaluation of cytokeratin, S-100 protein, glial fibrillary acidic protein, carcinoembryonic antigen, epithelial membrane antigen, smooth muscle actin, vimentin, B72.3, Ber-EP4, and milk fat globulin immunoreactivity was performed. Parallel to the morphologic similarity, the immunoprofiles of the basal cell adenocarcinoma and basal cell adenoma were quite similar. Both tumors showed reactivity patterns indicative of ductal epithelial and myoepithelial differentiation. In addition, reactivity to some polymorphic epithelial mucins was observed, which suggested glandular differentiation. The identification of antigens found normally in myoepithelial and epithelial cells supports the concept that these tumors are derived from pluripotential salivary gland epithelial cells. The comparable immunohistochemical profiles imply evolvement from similar cell lines and lead us to conclude that distinction between the two is not possible on the basis of these findings.
ELECTRON MICROSCOPY
Basal cell adenocarcinoma of the salivary gland: an ultrastructural and immunohistochemical study. Quddus MR, Henley JD, Affify AM, Dardick I, Gnepp DR. Rhode Island Hospital and Brown University School of Medicine, Providence 02903, USA.	Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999 Apr;87(4):485-92 Abstract quote OBJECTIVE: The purpose of this study was to examine the ultrastructural and immunohistochemical characteristics of basal cell adenocarcinoma. STUDY DESIGN: Three cases of basal cell adenocarcinoma of the salivary glands were studied by means of light microscopy, electron microscopy, and immunohistochemistry. RESULTS: Some of the architectural tumor patterns encountered were solid, some were trabecular, and some were mixed. Ultrastructurally, solid areas were composed of nonluminal cells, some of which contained tonofilaments and well-formed desmosomes; tubulo-trabecular areas differentiated into both luminal and nonluminal cells. Both growth patterns were associated with the formation of excess basal lamina, marginally and between nonluminal cells. Myofilaments were infrequent in nonluminal cells of solid or trabecular areas. Cytokeratin (AE1/AE3) stained all 3 tumors, more peripherally in the solid pattern and usually centrally in the trabecular areas; vimentin stained all 3 tumors diffusely; smooth muscle actin (IA4) stained all 3 tumors but was mainly confined to peripheral tumor cells in both the solid and the trabecular growth patterns; epithelial membrane antigen and carcinoembryonic antigen stained 1 of the 3 tumors, predominantly in the luminal cells; p53 oncoprotein was focally positive in 2 of the 3 tumors; Ki-67 stained less than 5% of the tumor cells in all cases; and c-erb-B2 was uniformly negative in all cases. Staining patterns of cytokeratin and actin varied with the architecture of the tumor. CONCLUSIONS: Neither ultrastructural characteristics nor immunohistochemistry findings appear to distinguish basal cell adenocarcinoma from basal cell adenoma.

Epidemiology
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/Immunohistochemistry/Electron Microscopy
Differential Diagnosis
Prognosis and Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS
INCIDENCE	<1% of all salivary gland tumors
AGE	Seventh decade
SEX	About equal

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
ADENDOID CYSTIC CARCINOMA
BASAL CELL CARCINOMA-METASTATIC
PLEOMORPHIC ADENOMA	With predominant basaloid pattern

PROGNOSIS AND TREATMENT	CHARACTERIZATION
PROGNOSTIC FACTORS
GENERAL
Basal cell adenocarcinoma of the salivary glands: comparison with basal cell adenoma through assessment of cell proliferation, apoptosis, and expression of p53 and bcl-2. Nagao T, Sugano I, Ishida Y, Hasegawa M, Matsuzaki O, Konno A, Kondo Y, Nagao K. Department of Surgical Pathology, Teikyo University, School of Medicine, Ichihara Hospital, Chiba, Japan.	Cancer 1998 Feb 1;82(3):439-47 Abstract quote BACKGROUND: Basal cell adenocarcinoma (BCAC) of the salivary gland is a rare tumor and recently described entity. Eleven cases of BCAC are presented here and compared with basal cell adenoma (BCA) through assessment of cell proliferative activity, apoptosis, and expression of p53, bcl-2, and epidermal growth factor receptor (EGFR) because these two tumors show close similarity in some cytologic and architectural characteristics. METHODS: Formalin fixed, paraffin embedded sections of 11 cases of BCAC and 9 cases of BCA, selected from the authors' files of 1851 primary tumors of the major salivary gland, were examined using immunostaining for Ki-67 (MIB-1), p53, bcl-2, and EGFR. In addition, apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling. RESULTS: The incidence of BCAC was 0.6% among patients with major salivary gland tumors in the current series. Nine cases of BCAC arose in the parotid gland and two were of submandibular gland origin. Approximately 50% of the patients had recurrences, but no patient developed metastases or died of disease. Vascular involvement (75%), perineural invasion (36%), and necrosis (45%) were common features. Cell proliferative activity, including mitotic count, Ki-67 labeling index (LI), and apoptotic index were significantly higher in BCAC than BCA. More than four mitotic figures per ten high-power fields or a Ki-67 LI > 5% appeared to be limited to cases of BCAC. Considering those cases expressing p53 or EGFR in > 10% of tumor cells as positive, 6 of the 11 BCAC cases were positive for p53 and 3 were positive for EGFR. In contrast, all BCA cases were negative for p53 and EGFR. Although all cases of BCA were strongly positive for bcl-2 (> 50% of tumor cells), 3 of 11 cases of BCAC were completely negative. CONCLUSIONS: BCAC is a rare salivary gland tumor with a relatively high recurrence rate. Examination of cell proliferation, apoptosis, and expression of p53, bcl-2, and EGFR were found to be useful in distinguishing malignant basal cell tumors from their benign counterparts arising in the salivary gland.
TREATMENT
SURGERY	Complete removal