We present a series of 16 salivary gland tumors with histomorphologic and immunohistochemical features reminiscent of secretory carcinoma of the breast. This is a hitherto undescribed and distinctive salivary gland neoplasm, with features resembling both salivary acinic cell carcinoma (AciCC) and low-grade cystadenocarcinoma, and displaying strong similarities to breast secretory carcinoma. Microscopically, the tumors have a lobulated growth pattern and are composed of microcystic and glandular spaces with abundant eosinophilic homogenous or bubbly secretory material positive for periodic acid-Schiff, mucicarmine, MUC1, MUC4, and mammaglobin. The neoplasms also show strong vimentin, S-100 protein, and STAT5a positivity. For this tumor, we propose a designation mammary analogue secretory carcinoma of salivary glands (MASC). The 16 patients comprised 9 men and 7 women, with a mean age of 46 years (range 21 to 75). Thirteen cases occurred in the parotid gland, and one each in the minor salivary glands of the buccal mucosa, upper lip, and palate. The mean size of the tumors was 2.1 cm (range 0.7 to 5.5 cm). The duration of symptoms was recorded in 11 cases and ranged from 2 months to 30 years. Clinical follow-up was available in 13 cases, and ranged from 3 months to 10 years. Four patients suffered local recurrences. Two patients died, 1 of them owing to multiple local recurrences with extension to the temporal bone, and another owing to metastatic dissemination to cervical lymph nodes, pleura, pericardium, and lungs. We have shown a t(12;15) (p13;q25) ETV6-NTRK3 translocation in all but one case of MASC suitable for analysis. One case was not analyzable and another was not available for testing. This translocation was not found in any conventional salivary AciCC (12 cases), nor in other tumor types including pleomorphic adenoma (1 case) and low-grade cribriform cystadenocarcinoma (1 case), whereas ETV6-NTRK3 gene rearrangements were proven in all 3 tested cases of mammary secretory carcinoma. Thus, our results strongly support the concept that MASC and AciCC are different entities.

Mucoepidermoid carcinoma is the most common salivary gland malignancy, and includes a spectrum of lesions ranging from non-aggressive low-grade tumors to aggressive high-grade tumors. To further characterize this heterogeneous group of tumors we have performed a comprehensive analysis of copy number alterations and CRTC1-MAML2 fusion status in a series of 28 mucoepidermoid carcinomas. The CRTC1-MAML2 fusion was detected by RT-PCR or fluorescence in situ hybridization in 18 of 28 mucoepidermoid carcinomas (64%). All 15 low-grade tumors were fusion-positive whereas only 3 of 13 high-grade tumors were fusion-positive. Highresolution array-based comparative genomic hybridization revealed that fusion-positive tumors had significantly fewer copy number alterations/tumor compared with fusion-negative tumors (1.5 vs 9.5; P ¼ 0.002). Twelve of 18 fusion-positive tumors had normal genomic profiles whereas only 1 out of 10 fusionnegative tumors lacked copy number alterations. The profiles of fusion-positive and fusion-negative tumors were very similar to those of low-and high-grade tumors. Thus, low-grade mucoepidermoid carcinomas had significantly fewer copy number alterations/tumor compared with high-grade mucoepidermoid carcinomas (0.7 vs 8.6; Po0.0001). The most frequent copy number alterations detected were losses of 18q12.2-qter (including the tumor suppressor genes DCC, SMAD4, and GALR1), 9p21.3 (including the tumor suppressor genes CDKN2A/B), 6q22.1-q23.1, and 8pter-p12.1, and gains of 8q24.3 (including the oncogene MAFA), 11q12.3-q13.2, 3q26.1-q28, 19p13.2-p13.11, and 8q11.1-q12.2 (including the oncogenes LYN, MOS, and PLAG1). On the basis of these results we propose that mucoepidermoid carcinoma may be subdivided in (i) low-grade, fusion-positive mucoepidermoid carcinomas with no or few genomic imbalances and favorable prognosis, (ii) high-grade, fusion-positive mucoepidermoid carcinomas with multiple genomic imbalances and unfavorable prognosis, and (iii) a heterogeneous group of high-grade, fusion-negative adenocarcinomas with multiple genomic imbalances and unfavorable outcome. Taken together, our studies indicate that molecular genetic analysis can be a useful adjunct to histologic scoring of mucoepidermoid carcinoma and may lead to development of new clinical guidelines for management of these patients.

Salivary duct carcinoma (SDC) is a rare and aggressive malignancy with poor prognosis. Its histomorphology is distinctly reminiscent of the ductal carcinoma of the breast. We reviewed the treatment and outcome of SDCs at a single tertiary care centre. Twenty-five cases of SDC of major salivary gland origin, diagnosed and treated at the Department of Otolaryngology, Head and Neck Surgery, Helsinki University Central Hospital, Helsinki, Finland, during a 14-year period from 1997 to 2011, were reviewed retrospectively. Survival outcome was analyzed for 18 patients with a minimum follow-up of 24 months. There were 16 male (64 %) and 9 female (36 %) patients with a median age of 61 years (range 36-82 years). The majority of the cases occurred in the parotid gland (n = 21, 84 %) followed by the submandibular gland (n = 4, 16 %). The primary treatment consisted of surgical resection in all cases and 17 (68 %) patients also underwent neck dissection. Most of the patients (n = 18, 72 %) were treated with postoperative radiotherapy. Seven patients (28 %) had a disease recurrence within a median follow-up time of 15 months (range 3-27 months). In the group (n = 18) with a minimum follow-up time of 24 months, the 2- and 5-year overall and disease-specific survival rates were 66, 41 % and 75, 55 %, respectively. These results confirm the aggressive nature of SDCs in major salivary glands. Diagnostics and management of these tumours need to be centralized in experienced surgical Head and Neck Oncology Centres, and new treatment strategies should be investigated.

High-grade transformation of acinic cell carcinoma (AciCC) (previously referred to as dedifferentiation) is a rare phenomenon characterized by histologic progression of low-grade AciCC to high-grade adenocarcinoma or undifferentiated carcinoma. We report 9 new cases with immunohistochemical analysis and examination of HER-2/neu and p53 genes to further define the profile of this tumor. Histologically, the high-grade component was composed of polymorphic cells with a high mitotic rate arranged in glandular and solid growth patterns with comedonecrosis. The MIB-1 labeling indices were elevated in the high-grade component, as compared with the low grade conventional AciCC. The high-grade component of AciCC was characterized by strong membrane staining for CK18 and beta-catenin, and nuclear staining for cyclin-D1. HER-2/neu, androgen receptor, C-kit, and epidermal growth factor receptor were absent from both low-grade and high-grade components. In contrast, S-100 protein, alpha-1-antitrypsin, and lysozyme were lost only in high-grade foci of transformed AciCC. The median age was 61 years (with range from 43 to 76 y). Lymph node (LN) metastases were found in 5 of 9 cases (56%). Distant metastases to the lungs (n=4), pleura (n=2), brain (n=3), and peritoneum (n=1), and paraaortic, paratracheal, and mediastinal LNs (n=2) were observed. Six of 9 patients (66%) died from tumor dissemination, all with a median overall survival of 4.3 years (range: 1 to 9 y). The high propensity for LN metastases indicates the need for neck dissection at the time of diagnosis.