Acinic cell carcinoma of the salivary glands: the prognostic relevance of DNA cytophotometry in a retrospective study of long duration (1965-1987)

Correlation of Histopathological Variants, Cellular DNA Content, and Clinical Outcome in Adenoid Cystic Carcinoma of the Salivary Glands

OBJECTIVE: To study the correlation between flow cytometrically measured DNA ploidy with prognostically important histopathologic groups and clinical outcome in patients with adenoid cystic carcinoma of the salivary glands.

STUDY DESIGN: 46 tumor specimens were analyzed flow cytometrically for DNA content and assessed for histological grade. Correlations were made between tumor DNA ploidy and histopathological grade, and disease-free and overall survival of these patients.

RESULTS: Of the 46 patients, 31 had a cribiform/tubular histologic pattern, and 15 had a solid pattern. 84% of the tumors with cribriform/tubular pattern were DNA diploid, compared with 33% of tumors that were graded solid. This difference proved to be statistically significant (χ 2 11.75, P = 0.0006). Overall and disease-free survival periods were longer for patients with DNA diploid tumors in both groups, 63% vs. 36% and 62% vs 38%, respectively.

CONCLUSIONS: Tumor DNA ploidy correlates with prognostically important tumor histopathology as well as overall and disease-free survival in patients with adenoid cystic carcinoma of the salivary gland. EBM rating: B-3.

Salivary acinic cell carcinoma: reappraisal and update

Epidemiologic and clinicopathologic features, therapeutic strategies, and prognosis for acinic cell carcinoma of the major and minor salivary glands are critically reviewed. We explore histopathologic, histochemical, electron microscopic and immunohistochemical aspects and discuss histologic grading, histogenesis, animal models, and genetic events. In the context of possible diagnostic difficulties, the relationship to mammary analog secretory carcinoma is probed and a classification is suggested. Areas of controversy or uncertainty, which may benefit from further investigations, are also highlighted.

[Acinic cell carcinoma of glandule parotidea presenting untypical clinical symptoms and their bad prognosis]

Differential diagnosis of neck tumours puts precedence on diagnosing neoplastic lesions. In the case of neck tumours, these are unfortunately late signs, but in patients with a primary neoplastic focus within the head and neck, neck tumour is often the first sign of the disease. The authors describe a clinical case of neck tumour with initially unclear etiology. The preoperative diagnostics including ultrasonography, thin-needle puncture, MRI, carotid angiography and videostroboscopy was significant for surgical treatment planning; yet it was the intraoperative clinical picture which indicated that the tumour derived from the inferior parotid pole. The preoperative histopathological diagnosis using thin-needle biopsy: cellulae carcinomatosae and the clinical picture resulted in block operation with neck lymphatic system removal and tissue defect reconstruction by means of a pectoral flap. The histopathological examination confirmed non-cornifying basal cell epithelioma only in the essential lesion with no metastases to lymph nodes and surrounding tissue margins free of infiltrates. Two and a half years after the procedure, the patient presented with a tumour localized on the front thoracic wall and two rapidly enlarging tumours in the nape of the neck. In the collected specimen of the tumour on the front thoracic wall, a diagnosis of acinic cell carcinoma was made. The deteriorating general condition of the patient, his cancer emaciation, problems with movement and suspected liver metastases confirmed by abdominal USG as well as radiological bone lesions resulted in the abandonment of surgical treatment due to disseminated neoplastic process and the patient was referred for palliative care.

[DNA ploidy and proliferative activity in salivary gland tumours]

DNA ploidy and S-Phase fraction (SPF) of 279 salivary gland tumours were analysed using high-resolution DNA flow cytometry. All 229 benign neoplasms were diploid while 12 of 50 malignant tumours showed cell populations with aneuploid DNA content. The SPF values of diploid malignancies were significantly higher if compared with pleomorphic adenomas but did not differ from that of the zystadenolymphoma (Warthin tumour) group. While aneuploidy represents a distinct indicator of malignancy SPF values are of minor relevance for dignity assessment in salivary gland tumours.

Acinic cell carcinoma of maxillary sinus

Acinic cell carcinoma is a tumor that occurs most commonly in the parotid glands. We have experienced a rare case of acinic cell carcinoma of the left maxillary sinus. The patient was a 71-year-old female. She noticed her left nasal congestion and epiphora from left eye in April 1994. She had a history of left maxillary sinus surgery in February, 1972. Antrotomy was performed and histopathological examination of specimen from the maxillary sinus proved acinic cell carcinoma. The tumor was considered to be the recurrence 22 years after initial surgery, because it coincided with the surgical specimen of previous surgery. Radical resection of maxilla was performed for complete resection of tumor with palate reconstruction by left scapula and latissimus dorsi myocutaneous flap. No recurrence is observed for more than 4 years after surgery. Although this tumor is of low grade malignancy, complete resection with adequate surgical margin is advisable due to high incidence of this tumor to recur after long periods of time.

Clear cell neoplasms in salivary glands: clearly a diagnostic challenge

Although infrequent, salivary gland tumors with a dominant population of clear staining cells present problems in differential diagnosis. Mucoepidermoid carcinoma, acinic cell adenocarcinoma, "clear cell" oncocytoma, epithelial-myoepithelial carcinoma, clear cell adenocarcinoma, and metastatic renal cell carcinoma are considered in the differential diagnosis. This review focuses on this heterogenous group of clear cell neoplasms and attempts to clarify some of the features that help distinguish one neoplasm from another.

Well-differentiated acinic cell carcinoma of salivary glands associated with lymphoid stroma

In a multicenter study, 69 acinic cell carcinomas of the salivary glands were identified, of which 12 constituted what the authors believe to be a distinct subgroup. Their most noticeable feature was a dense lymphoid stroma with well-developed germinal centers, surrounding a sometimes scanty epithelial component, which in each case had a microcystic growth pattern. All these tumors were enveloped by a thin fibrous pseudocapsule, thus mimicking an intraparotid lymph node containing a metastasis. All 12 cases showed low MIB1 proliferative activity, with a mean index of 1.7% (range, 0.5 to 3.7). All patients remained well without recurrence or metastasis in followup periods of 19 months to 14 years. A second subgroup of nine acinic cell carcinomas also possessed a heavy lymphoid stroma with germinal centers, but its distribution was more patchy than in the first subgroup, and in addition, the fibrous pseudo-capsule was incomplete or absent. In each case the epithelial growth pattern was other than microcystic. These tumors had significantly higher MIB1 indices (mean, 17%; range, 3.4 to 45). In contrast to the first subgroup, only three of nine patients remained well with no further disease. The other six patients developed recurrences or metastases, and two died of disseminated cancer. In view of the clinical and pathological data, it is speculated that the tumor foci lacking lymphoid stroma in each of the second subgroup possibly represented a clone of high-grade malignancy arising within a low-grade acinic cell carcinoma with lymphoid stroma.

Prognostic significance of DNA ploidy in mucoepidermoid carcinoma

Thirty-four mucoepidermoid carcinomas were studied retrospectively with regard to histological and clinical parameters. In 28 of the tumors DNA patterns were also assessed using flow cytometry. Twenty-two of the 28 tumors (79%) were DNA diploid and 6 (21%) DNA aneuploid. Two tumors (7%) showed intratumoral DNA as indicated by different stemlines in specimens investigated from different parts of the tumor. DNA ploidy correlated significantly with cervical lymph node status (P < 0.01), but not with tumor size or histological grade. The mean S-phase value was 2.7% and was significantly higher in aneuploid samples than in diploid ones (P < 0.05). The recurrence rate was significantly lower for patients with stage I and II tumor compared with those with stage III and IV disease (P < 0.01). Five aneuploid tumors showed significantly higher recurrence rates (5/6) than the diploid ones (1/22) (P < 0.01). In univariate analysis for survival, only N stage tumor (P < 0.05) and tumor DNA ploidy (P < 0.0003) had significant prognostic influence. Thus, DNA ploidy seems to be a valuable parameter for evaluating the biological behavior of mucoepidermoid carcinomas of the salivary glands.

Hybrid tumours of salivary glands. Definition and classification of five rare cases

Hybrid tumours are very rare tumour entities which are composed of two different tumour entities, each of which conforms with an exactly defined tumour category. The tumour entities of a hybrid tumour are not separated but have an identical origin within the same topographical area. In contrast, biphasically differentiated tumours are a mixture of two cellular patterns with a corresponding term in the tumour classification. Examples of a biphasic differentiation are: basaloid-squamous carcinoma, adeno-squamous carcinoma or sarcomatoid carcinoma, and epithelial-myoepithelial carcinoma, mucoepidermoid carcinoma or adenoid cystic carcinoma. Hybrid tumours must also be distinguished from the multiple occurrence of salivary gland tumours which can develop syn- or metachronously. In the tissue samples of more than 6600 salivary gland tumours covered by the Salivary Gland Register (Institute of Pathology, University of Hamburg, Germany) only 5 cases of hybrid tumours were recorded between 1965 and 1994. This means less than 0.1% of all registered tumours. Case 1 was a very rare example of a hybrid adenoma with differentiation as a basal cell adenoma and a canalicular adenoma of the parotid gland. The similar cellular origin of both types of adenoma may be an explanation for its development in a hybrid adenoma. Case 2 is a hybrid tumour with a composition of basal cell adenoma and a glandular type of adenoid cystic carcinoma. In both types of tumours the two cell types (duct-lining cells and modified myoepithelial cells) have a similar histogenetic origin. Therefore, the development of the both cell types in a hybrid tumour with two trends of differentiation is possible. Case 3 represents a hybrid adenoma as a mixture of a Warthin tumour and a sebaceous adenoma. Although inclusions of sebaceous cells are observed in Warthin tumours, this hybrid tumour shows a composition of two different epithelial structures in a varied mixture. Case 4 is a very rare and unique hybrid carcinoma with two absolutely different components: acinic cell carcinoma and salivary duct carcinoma. The poor prognosis of this hybrid carcinoma is determined by the salivary duct carcinoma. Case 5 represents a hybrid carcinoma whose two components have a similar histogenetical basis: epithelial-myoepithelial carcinoma and a glandular type of adenoid cystic carcinoma. Both carcinomas are composed of variable proportions of ductlining cells and myoepithelial cells.

Clinico-pathological predictors of recurrence for acinic cell carcinoma

The biological behaviour of acinic cell carcinomas, even if well differentiated, is unpredictable. We studied 45 patients with acinic cell carcinoma followed-up from 10 to 379 months (5 year recurrence-free and survival rate of 69% and 81% respectively), and compared clinico-pathological parameters with outcome. The presence of a predominately solid architecture was strongly associated with a poor outcome (P < 0.01) and this was the only independent prognostic variable when log rank testing was performed. Tumour size (> 2.75 cm) was a significant predictor of recurrent deep parotid lobe involvement, the presence of cervical nodal disease and lymphocytic infiltration, although not significant, factors showed a tendency towards recurrence. For acinic cell carcinoma, the predominant solid architecture would appear to be a strong predictor of recurrence.

DNA flow cytometry of reclassified subtypes of malignant salivary gland tumors

Malignant salivary gland tumors are rare, constitute a heterogeneous group and are often difficult to diagnose histologically. This is borne out by the fact that in the present study 43.2% of 118 salivary gland tumors originally diagnosed as mucoepidermoid, acinic cell and adenoid cystic carcinomas had their original diagnosis altered upon reclassification. Patients with confirmed adenoid cystic carcinomas had a much worse prognosis than those with mucoepidermoid and acinic cell carcinomas. DNA flow cytometry showed that very few of the above mentioned three types of malignant neoplasms revealed aneuploid DNA stemlines, indicating that this is not a relevant prognostic tumor marker within the groups. However, several of the tumors that had their diagnosis changed, mostly to undifferentiated adeno- or squamous cell carcinomas, showed aneuploid DNA stemlines. The survival time of patients with aneuploid tumors was considerably reduced compared to those with diploid tumors. Among confirmed acinic cell, mucoepidermoid and adenoid cystic carcinomas the S-phase fraction was a significant prognostic factor, as it was among all tumors examined. This indicates that DNA aneuploidy and S-phase fractions are potential prognostic factors for malignant salivary gland tumors, and that DNA flow cytometry may assist the characterization of such tumors.

Cell proliferation correlates with prognosis in acinic cell carcinomas of salivary gland origin. Immunohistochemical study of 30 cases using the MIB 1 antibody in formalin-fixed paraffin sections

Immunohistochemical staining with the MIB 1 antibody was used to assess cell proliferation in 30 cases of acinic cell carcinoma of salivary glands. Until now, no prognostic factors have been available for these rare tumours. The MIB 1 monoclonal antibody recognizes the Ki-67 antigen in formalin-fixed, paraffin-embedded tissues. A MIB 1 index was developed as a means of expressing the percentage of MIB 1-positive tumour cell nuclei, and the tumours were scored without prior information of clinical behaviour. The staining results were then compared with the clinical outcome of the patients. All eight patients who developed tumour recurrences had MIB 1 indices higher than 5 per cent. Tumour recurrences could be predicted even in cases of bland morphology and low mitotic rate. Three patients died of their recurrent tumours, and had MIB 1 indices of 56.2, 12.7, 7.8 per cent in their primary tumours. Five of seven patients with MIB 1 indices higher than 10 per cent had unfavourable outcomes. None of the 17 patients with MIB 1 indices lower than 5 per cent developed recurrences during follow-up periods up to 30 years. The present results indicate that MIB 1 staining appears to be a significant prognostic factor in acinic cell carcinomas of salivary gland origin.

Acinic cell carcinoma arising in a parotid lymph node

The case of a 37-year-old woman with primary acinic cell carcinoma arising in an intraparotid lymph node is presented. The patient is free of disease 20 months after superficial parotidectomy. This is probably the first histologically documented case of acinic cell carcinoma arising from intranodal salivary gland tissue. Awareness of possible malignant alteration of ectopic salivary gland tissue in lymph nodes is essential.

Salivary neoplasms of the palate: a flow cytometric and clinicopathological analysis

In order to test the clinical and prognostic significance of flow cytometrically assessed DNA content in minor salivary gland tumours we evaluated 75 neoplasms of the palate, 55 of which were carcinomas. Benign neoplasms were exclusively DNA diploid with low S-phase fractions while 22 per cent of malignant tumours manifested a DNA aneuploidy and 23.5 per cent high S-phase fractions (> 5 per cent). Significant statistical correlations between DNA content and tumour size, histological grade, lymph node metastasis and lethality were observed. Our findings suggest a potentially important role for flow-cytometry in the evaluation of these neoplasms.

Acinic cell carcinoma of the parapharyngeal space: case report

We describe a case of acinic cell carcinoma (ACC) of the parapharyngeal space in a 58-year-old woman. A tumor originating from the deep lobe of the parotid gland was totally excised by an external cervical approach. The occurrence of ACC in the parapharyngeal space is extremely rare. We discuss the management, especially surgical procedure, of ACC in this area.

Nucleolar organizer regions in malignant salivary gland tumors

Proliferative activity of carcinomas arising from salivary glands was analyzed by enumeration of argyrophilic nucleolar organizer regions (AgNORs). The mean numbers of AgNORs in the various tumors were as follows: mucoepidermoid carcinoma, 2.20; acinic cell carcinoma, 2.51; adenoid cystic carcinoma (ACC), 2.57; carcinoma in pleomorphic adenoma, 1.00 (benign component) and 3.99 (cancer-bearing area); salivary duct carcinoma, 4.49; polymorphous low-grade adenocarcinoma, 3.37; sebaceous carcinoma, 2.57; oncocytic carcinoma, 4.63; adenocarcinoma, 4.53. Cells of most tumors showed heterogeneous activity within the same tumor. In mucoepidermoid carcinoma, the mucous cells had suppressed activity in comparison with the epidermoid cells and intermediate cells. In ACC, the activity of the tumor cells increased according to growth pattern in the order tubular, glandular and solid. In carcinoma in pleomorphic adenoma, vigorous proliferative activity was observed in the malignant component, whereas less active cells were seen in the myxoid or chondroid matrix. AgNOR staining was useful for distinguishing benign from malignant regions in carcinoma in pleomorphic adenoma. Our results suggest that mucoepidermoid carcinoma, acinic cell carcinoma and ACC, except for that with a solid growth pattern, may be considered as low-grade malignancies, whereas solid-type ACC, the cancer component in carcinoma in pleomorphic adenoma and some of the other carcinomas have high-grade malignant behavior.

The World Health Organization's Histological Classification of Salivary Gland Tumors. A commentary on the second edition

The second edition of the World Health Organization's Histological Classification of Salivary Gland Tumors is more extensive and detailed than the previous edition published 20 years ago. The new edition is based on data regarding newly described tumor entities and the behavior and prognosis of the previously classified tumors. The distinct morphologic features of monomorphic adenomas justify their separation for purposes of identification. Among the carcinomas, various types were distinguished for purposes of recognition, prognosis, and treatment. The term tumor was replaced by carcinoma in the following two entities: acinic cell carcinoma and mucoepidermoid carcinoma. The tumor-like lesions were described in more detail.

Acinic cell carcinoma of the salivary glands. A review of 20 new cases

Twenty patients with acinic cell carcinoma of the salivary glands are presented. Seventeen tumours were located in the parotid and three in minor salivary glands, one being considered intraosseous. According to the growth patterns, they were classified as solid-acinar in 8 patients, microcystic in 5 patients, follicular in 3 patients and papillocystic in 4 patients. 9 cases were considered high grade malignant tumours and among the 11 well-differentiated, 2 suffered dedifferentiation in local recurrences. Local recurrence appeared in 9 cases. Three cases had nodal disease on admission while 5 developed this during the course of the disease. Distant metastasis appeared in 2 cases. Local recurrence and nodal disease correlated with the degree of differentiation and state of the margins in the surgical specimen. We recommend an aggressive surgical approach followed by postoperative radiotherapy for the undifferentiated tumours and extensive ones. For the limited and better differentiated, a more limited excision, such as total parotidectomy preserving the facial nerve is suggested.

Histopathologic grading of salivary gland neoplasms: II. Acinic cell carcinomas

Acinic cell carcinomas display varied cytoarchitectural patterns of growth that should allow for formulation of histopathologic grading. Grading of these carcinomas may serve to identify subsets whose biologic behavior is more aggressive than the usually accepted low-grade behavior of acinic cell carcinomas as a group. To that end, a three-level histopathologic grading scheme is presented.

DNA flow cytometry of acinic cell carcinomas of major salivary glands

Fifteen acinic cell carcinomas from an equal number of patients were analysed for their DNA content and proliferative (S-phase) index by flow cytometry from archival tissues. Seven of the carcinomas manifested a diploid DNA content. None of the patients with diploid acinic cell carcinomas died of their carcinomas and none developed metastases in follow-up periods extending for 10 or more years. Four of eight patients with aneuploid acinic cell carcinomas have died because of their malignancies within a 10 year period after the first surgical removal of the carcinoma. Five of the eight patients exhibited metastases. Although the number of cases does not permit strong correlations between histopathological features, abnormalities in DNA content and outcome of patients, it was noted that carcinomas with prominent necrosis, tubuloductal differentiation and 'dedifferentiated' areas displayed more aggressive biological courses.

Prognosis of salivary adenocarcinomas. A retrospective study of 52 cases with special regard to cytochemically assessed nuclear DNA content

52 salivary adenocarcinomas of the years 1965-1980 from the files of the Salivary Gland Registry, Institute of Pathology, University of Hamburg, were evaluated retrospectively with regard to clinical follow up and cytochemically assessed nuclear DNA content. The age distribution showed a peak from the 6th to 8th decade (range 3 to 87 years). The m:f ratio was 1:1.36, the mean age was 59.3 years. Over 80% of the tumours were located in the major salivary glands. The clinical course was characterized by metastases present at initial diagnosis (16 cases), subsequent development of metastases (9 cases), local recurrence (15 cases) or death from tumour (10 cases) and was related to differentiation, grade 3 tumours showing the worse clinical courses. In 37 cases, nuclear DNA content was determined by a single scanning cytophotometry device. 28 cases were diploid, 9 were atypical. The clinical course was significantly related to the histogram type, atypical tumours showing a dismal prognosis.