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

Mucoepidermoid carcinoma, acinic cell carcinoma, and adenoid cystic carcinoma on fine-needle aspiration biopsy and The Milan System: an international multi-institutional study

BACKGROUND

We evaluated the diagnostic accuracy (DA), risk of neoplasm (RON), and risk of malignancy (ROM) for the commonly encountered malignant salivary gland tumors mucoepidermoid carcinoma (MECa), acinic cell carcinoma (ACCa), and adenoid cystic carcinoma (ADCa) applying The Milan System for Reporting Salivary Gland Cytology (MSRSGC).

MATERIALS AND METHODS

The cytology archives from 2007 to 2017 of 9 academic institutions were searched for salivary gland FNAs for the following key words mentioned either in the principal and/or differential diagnosis: MEC, ACCa, and ADCa. The original cytology diagnosis was retrospectively classified according to the MSRSGC. Patient demographics, biopsy site, and available surgical follow-up were recorded. The final analysis included only cases with surgical follow-up.

RESULTS

A total of 212 salivary gland FNAs were included. Based on retrospective reclassification according to MSRSGC, 97 of 212 (46%) FNA cases carried a diagnosis of malignancy specific for either MECa, ACCa, or ADCa. In the remaining 115 cases, 24 of 212 (11%) were reclassified as suspicious for malignancy (SM) and 91 of 212 (43%) as salivary gland neoplasm of uncertain malignant potential (SUMP). The DA for MECa, ACCa, and ADCa was 78.7%, 75% and 89%, respectively. The RON was 100% for all 3 tumors and the ROM was 93.6% for MECa, 96.8% for ACCa, and 94.4% for ADCa.

CONCLUSIONS

The DA of 78.7% for MECa, 75% for ACCa, and 89% for ADCa is reasonable in FNA specimens. Although the management of definitive cases of malignancy remains unchanged, the MSRSGC provides a ROM for SM and SUMP categories, which can improve patient management.

Cytological features of basal cell adenocarcinoma of the salivary glands

The cytological features of basal cell adenocarcinoma (BAC) of the salivary gland, a rare carcinoma, have not been well described. This study included patients who were histopathologically diagnosed with BAC and who underwent preoperative fine-needle aspiration cytological examination. Cytological characteristics, including background, arrangement and shape of the neoplastic cells, nuclear and cytoplasmic features, and presence of stromal spindle cells, were reviewed. Seven patients were enrolled in the study. The cytological specimens were cellular and composed of large or small clusters with occasional discohesive neoplastic cells at the periphery. The predominant cellular morphology was spindle-shaped in four cases, and small round-shaped in three cases. These neoplastic cells were tightly packed, showed high cellularity and overlapping nuclei, and had mildly to moderately enlarged round to oval nuclei with occasional small nucleoli and scant cytoplasm. Stromal spindle cells were observed around the basaloid cells in three cases (42.9%). All histology-proven stromal spindle cell-positive cases had stromal spindle cells in the cytological specimens. The study findings clearly demonstrate the relatively high frequency of stromal spindle cells in cytological specimens of BAC. This finding is characteristic of BAC, although basal cell adenoma of salivary gland frequently has stromal spindle cells in the cytological specimens. The characteristic that differentiates BAC from basal cell adenoma is the presence of tightly packed and high cellular clusters with discohesive neoplastic cells. An understanding of these cytological features can aid the cytodiagnosis of BAC.

Cytological features of basal cell adenoma of salivary glands: Analysis of 19 cases emphasizing stromal spindle cells

BACKGROUND

Basal cell adenoma (BCA) of the salivary gland is a relatively rare benign tumor. Although the presence of stromal spindle cells is a characteristic histopathological feature, this finding has not been the focus of much attention in the cytodiagnosis of BCA. Thus, we analyzed the cytological features of BCA, especially the presence of stromal spindle cells.

METHODS

Patients who were histopathologically diagnosed with BCA and underwent preoperative fine-needle aspiration cytological examination were enrolled in this study. The cytological characteristics including arrangement and shape of the neoplastic cells, nuclear and cytoplasmic features, and the presence of stromal spindle cells were reviewed.

RESULTS

Nineteen patients were enrolled in the study. The cytological specimens were cellular and composed of small or large clusters or both. The neoplastic cells had scant cytoplasm and small round to oval nuclei. Basement membrane-like material was observed in 57.9%, and peripheral palisading was noted in 84.2%. Loose aggregates of stromal spindle cells were present in 63.2%, and the stromal spindle cells shown in the histological examination of 85.7% of cases were expressed in the cytological specimens.

CONCLUSION

This study clearly demonstrated the relatively high frequency of stromal spindle cells in cytological specimens of BCA. This finding is characteristic of BCA, and therefore, the combination of cytological features, including packed clusters of neoplastic cells with scant cytoplasm and small nuclei, peripheral palisading, and basement membrane-like material, and the presence of stromal spindle cells could increase the diagnostic success of BCA.

Cytological investigation of a first case of basal cell adenocarcinoma arising in the minor salivary glands. Case report and review of the literature

Basal cell adenocarcinoma (BCAC) of salivary glands is uncommon low-grade malignancy. Only 19 cases of preoperative cytology were reported up to date. We present here a new case of BCAC arising in the minor salivary gland. Tumor was composed of clustered or isolated roundish, dark cells with small and regular nuclei. Chromatin was dusty with small nucleoli. Cytoplasm was gray and scant. Clusters showed typical and characteristic basal architecture with peripheral palisading neighboring eosinophilic basal membranes. A false-negative diagnosis of basal cell adenoma was rendered. In our knowledge it is the first cytological description of BCAC arising in the minor salivary gland.

New diagnostic markers in salivary gland tumors

Parotid gland tumors are a rare and heterogeneous entity. Molecular markers are sparse. The aim of the study was to identify new diagnostic markers in benign and malignant salivary tumors. A tissue microarray was constructed with 158 tumor samples. Expression of 21 tumor antigens involved in tumor cell survival and known for prognostic potential was assessed immunohistochemically in all parotid gland samples. CEA, Cox-1, Cox-2, Sigma, beta-Catenin, WISP-1 and PDGF-beta were differently regulated in benign and malignant parotid tumors. Subsequently, these seven proteins entered the step-wise logistic regression analysis. As a second step, we defined a score for differentiating benign versus malignant parotid lesions: 4*CEA+15*Cox-1+4*Cox-2+4*Sigma+3*PDGF-beta+10*beta-Catenin+14*Wisp1. Sensitivity and specificity of 94 and 83% were reached. Besides routine hematoxylin and eosin staining, definition of new diagnostic markers and subsequently a new diagnostic score are an attempt to create an additional tool for the diagnosis of parotid gland tumors.

Fine needle aspiration cytology of basal cell adenoma of the salivary gland: a cytohistological correlation study of 35 cases

OBJECTIVE

In order to evaluate the possibility of a specific cytological recognition of basal cell adenoma (BCA) we reviewed our experience with 35 histologically proven cases. Few series describing cytological features of BCA are available and diagnostic cytological criteria are not well established.

METHODS

This study was based on 41 cytology samples from 35 patients with BCA. Thirty-five aspiration procedures were performed pre-operatively and six on tumour recurrence. Nineteen of the 35 patients were men and 16 women. The mean age at diagnosis was 55 years old (range 24-92). The series includes one non-representative case. Except for one tumour located in the upper lip, all of them involved the parotid gland.

RESULTS

Aspirates were cellular, showing groups with dense, homogeneous metachromatic stroma and single cells. Relevant features were the trident-like configuration of groups, intimate relationship between neoplastic cells and stroma and cellular polymorphism. In approximately half of the cases a precise diagnosis was given. Most of the remaining tumours were diagnosed as benign but they were difficult to differentiate from pleomorphic adenoma. Regarding malignancy, there were two misdiagnoses of acinic cell carcinoma, due to high epithelial cellularity along with scarcity of stroma, and one case was considered to be suspicious of malignancy.

CONCLUSION

BCA shows characteristic cytological features that allow a precise diagnosis. The main differential diagnosis is epithelial-rich pleomorphic adenoma, while acinic cell carcinoma is a potential false positive.

Basal cell adenoma versus pleomorphic adenoma of the parotid gland: CT findings

OBJECTIVE

Basal cell adenoma is a rare benign epithelial tumor of the salivary gland. The objective of this study is to present the CT findings of parotid basal cell adenoma. We also compare CT findings of basal cell adenoma with those of pleomorphic adenoma, the most common parotid tumor, to determine whether any features on CT can help differentiate these two entities.

CONCLUSION

Basal cell adenomas of the parotid gland are located chiefly in the superficial lobe. They are generally round, well-circumscribed tumors that show heterogeneous enhancement on CT. The age of the patient and the attenuation on unenhanced and contrast-enhanced CT may help in differentiating basal cell adenoma from pleomorphic adenoma of the parotid gland.

Fine-needle sampling of primary neuroendocrine carcinomas of salivary glands: cytohistological correlations and clinical analysis

Fine-needle samplings of nine examples of primary neuroendocrine carcinoma of salivary glands were evaluated for their cytologic characteristics and were correlated with the corresponding histological sections. Consistent cytological findings were dispersed or loose clusters of poorly differentiated small- to intermediate-sized cells and occasional smudged nuclei. Mild to moderate nuclear pleomorphism, scant or absent cytoplasm, and nuclear molding were also observed. Rosette-like patterns and multinucleated cells were occasionally seen. Immunostaining of one recent case showed positivity for chromogranin and keratin. The differential diagnosis of primary and metastatic tumors with neuroendocrine features of the salivary glands is discussed.

Fine-needle aspiration cytology of salivary gland: a review of 341 cases

Three hundred and forty-one salivary gland fine-needle aspiration (FNA) cytology specimens taken over a 6-yr period were reviewed and correlated with clinical and/or histological findings. The aspirates were derived from parotid gland (212 cases), submandibular gland (124 cases), and minor salivary gland (5 cases). The major diagnostic categories were unsatisfactory (10 cases), normal (100 cases), sialadenitis (74 cases), cyst (34 cases), lipoma (5 cases), pleomorphic adenoma (55 cases), Warthin's tumor (36 cases), and malignancy (27 cases). The latter included 14 primary salivary neoplasms (4 lymphomas of mucosa-associated lymphoid tissue (MALT) type, 3 adenocarcinomas, 2 squamous carcinomas, 2 adenoid cystic cacinomas, and one case each of carcinoma ex pleomorphic adenoma, undifferentiated carcinoma, and high-grade mucoepidermoid carcinoma), and 13 metastases, 9 of which were derived from squamous carcinomas of head and neck origin. Clinicopathological review showed that 88 of 91 (97%) benign epithelial tumors and 27 of 31 (87%) malignant neoplasms with adequate FNA sampling were accurately diagnosed cytologically. False-negative results were caused by sampling error (7 cases), most notably in cystic tumors, or were due to misinterpretation of uncommon neoplasms (3 cases). The overall sensitivity, specificity, and accuracy were 92%, 100%, and 98%, respectively. FNA cytology provides accurate diagnosis of most salivary gland lesions and contributes to conservative management in many patients with nonneoplastic conditions.