The cytological features of mammary analogue secretory carcinoma

A series of 6 molecularly confirmed cases




Mammary analogue secretory carcinoma (MASC) of the salivary glands is a newly described tumor entity associated with the t(12;15)(p13;q25) ETV6-NTRK3 translocation. Early studies have shown this tumor to be a distinct entity with histologic, biologic, and clinical differences from acinic cell carcinoma and adenocarcinoma, not otherwise specified. Because this tumor was described only recently, it remains relatively unknown outside of head and neck specialty pathology centers.


In the current study, 6 cases of fine-needle aspiration cytology from histologically and/or molecularly confirmed cases of MASC are presented.


Using cytomorphology, MASC primarily raises the differential diagnosis of an oncocytic salivary gland tumor but there are some features that can suggest the specific diagnosis of MASC. The 6 cases presented in the current study all demonstrated at least focal cytoplasmic vacuolization and papillary formations on smears. MASC can be differentiated from acinic cell carcinoma by a lack of periodic acid-Schiff diastase–positive zymogen granules and S-100 protein positivity.


The results of the current study the ability of ETV6 break-apart fluorescence in situ hybridization to detect gene rearrangement on cell block material. This is the first report of a case of MASC prospectively diagnosed on a cytology specimen. Cancer (Cancer Cytopathol) 2013;121:234–41. © 2012 American Cancer Society.


Mammary analogue secretory carcinoma (MASC) is a newly described salivary gland malignancy that shares morphologic and molecular similarities with secretory carcinoma of the breast.[1] Both entities are known to carry a t(12;15)(p13;q25) translocation.[2] Historically, most MASC were categorized as acinic cell carcinoma (AciCC) or adenocarcinoma, not otherwise specified.[3] Although MASC does recapitulate many of the morphologic features of AciCC, the absence of true zymogen granule formation and the presence of eosinophilic, vacuolated tumor cells with prominent mucin production distinguish MASC from AciCC.

To the best of our knowledge, there currently is minimal experience with the cytologic evaluation of MASC by fine-needle aspiration (FNA), which is limited to 2 separate case reports of a MASC of the submandibular gland and MASC of the parotid gland.[4, 5] In the current study, we characterized the cytologic features of 6 cases of MASC on FNA and demonstrated the usefulness of ancillary testing on cytologic material to resolve differential diagnostic considerations.


Case Selection

Six cases of MASC that were confirmed both morphologically and by fluorescence in situ hybridization (FISH) with FNA material were retrieved from the University of Pittsburgh (cases 1-3), University of Virginia (cases 4 and 5), and Columbia University (case 6). Aspirates from the University of Pittsburgh were from previously reported cases of MASC.[3, 6]

Immunohistochemistry and ETV6 FISH

Immunohistochemical studies for S-100 protein and mammaglobin were performed. Briefly, polyclonal rabbit anti–S-100 protein antibody (clone Z0311; Dako, Carpinteria, Calif) was used at a dilution of 1:500 after Cell Conditioning 1 (CC1) pretreatment on a Ventana processor (Ventana Medical Systems Inc, Tucson, Ariz). A mixture of rabbit and mouse monoclonal antimammaglobin antibody (clones 304-1A5 and 31A5; Zeta Corporation, Sierra Madre, Calif) was used at a prediluted concentration after mild CC1 pretreatment on a Ventana processor. FISH using break-apart ETV6 probes (Abbott Molecular Inc, Des Plains, Ill) was performed as previously described.[7] Nuclei with split red and green signals indicated ETV6 gene rearrangement. Chromosomes with normal ETV6 genes demonstrated a yellow signal (overlapping green and red). A total of 60 analyzed cells were required to consider the sample adequate. Cases in which > 20% of analyzed cells had split red and green signals were considered to be positive for the translocation. Nuclei were counterstained with 4′,6-diamidino-2-phenylindole. Molecular confirmation of ETV6 gene rearrangement and thus the diagnosis of MASC were performed on the surgical resection specimens in cases 1 through 5 whereas case 6 was confirmed to harbor an ETV6 gene rearrangement on the actual cell block material from the FNA. FISH testing was repeated on cell block material from the aspirates taken from cases 1 and 2.


Clinical Parameters

The clinical features of the 6 cases in the current study are summarized in Table 1. The average age of the 3 men and 3 women was 43.7 years (range, 27 years-66 years). All patients presented with a mass lesion. Four cases originated in the parotid gland (cases 1, 3, 5, and 6), whereas case 2 was diagnosed in the buccal mucosa and case 4 was from the submandibular gland. Five patients (cases 1-5) subsequently underwent surgical resection (mean of 5.4 weeks after initial cytologic diagnosis), 3 of whom also underwent a cervical lymph node dissection (cases 2, 4 and 5), with only case 4 found to have metastatic disease to a cervical lymph node. At the time of last follow-up, 4 of these 5 patients were free of disease (mean follow-up, 4.5 months); the sixth patient was lost to follow-up. Despite having a confirmed diagnosis of MASC, 1 patient (case 6) opted not to undergo surgical treatment and was alive with disease at the time of last follow-up.

Table 1. Clinical Summary of Patients With Confirmed MASC and Prior FNA
CaseSexAge, YearsSiteTreatmentGreatest Dimension, cmStatusFollow-up, Months
  1. Abbreviations: AFD, alive and free of disease; AWD, alive with disease; FNA, fine-needle aspiration; LND, lymph node dissection; MASC, mammary analogue secretory carcinoma; NA, not available.
1Woman51Parotid glandResection2.5AFD4
2Man51Buccal mucosaResection and LND2.1AFD4
3Man27Parotid glandResection1AFD4
4Woman44Submandibular glandResection and LND1.8NANA
5Woman23Parotid glandResection and LND1.2AFD6
6Man66Parotid glandNoneNAAWD2

Cytomorphologic Features

A summary of the cytomorphologic features is presented in Table 2. Original diagnoses of the aspirates were salivary gland papillary neoplasm, favor papillary AciCC (case 1); low-grade neoplasm (cases 2, 4, and 5); benign salivary gland epithelium (case 3); and MASC (case 6). In the patient in case 2, AciCC was considered high on the list of differential diagnostic possibilities in addition to cystadenoma and mucoepidermoid carcinoma (MEC). MASC was considered less likely because of negative S-100 protein staining noted on the cell block preparation. All 6 cases of MASC FNA cytology had several features in common on smear preparations. Each showed cellular smears comprised of tumor cells in groups and single cells in the background. The majority of cases demonstrated clusters of cells ranging from tight, small, acinar-like structures to larger, papillary, arborizing structures with transgressing vessels (Figs. 1A and 1B). Case 2 also demonstrated tubuloglandular structures (Fig. 1C). Cells had abundant cytoplasm and many had eccentrically located nuclei (Fig. 1D). All cases demonstrated a characteristically vacuolated cytoplasm, with the majority having mostly multiple small vacuoles (Figs. 1D and 2A), but occasional cases had prominent monovacuolated cells, some of which resembled signet ring cells (Fig. 2B). Some of these vacuoles contained mucin, as evidenced on special stains of cell block material (Fig. 3B). The cytoplasm of the tumor cells was otherwise finely granular and was found to be very eosinophilic on hematoxylin and eosin-stained smears (Fig. 2C). Overall, the nuclear grade ranged from low to moderate, with the majority of cells demonstrating uniform round nuclei. Occasionally, larger nuclei were present in most cases and some cases showed mild nuclear membrane irregularities (Fig. 2D). Binucleation was noted occasionally (Fig. 1D). Nucleoli were observed in all cases but were more prominent in cases with a moderate nuclear grade (Figs. 1C and 1D). Mitotic figures were not identified in any case. Extracellular material was common and was usually comprised of mucin (cases 1, 2, 5, and 6) that in some cases was abundant (Fig. 2A). Other cases demonstrated dense eosinophilic debris (case 3) or metachromatic globular material (cases 4 and 5).

Figure 1.

Cytomorphology of mammary analogue secretory carcinoma on smear preparations is shown. (A) In case 1, prominent papillary architecture with tumor cells clinging to fibrovascular cores in an arborizing pattern was observed (Papanicolaou stain, × 40). (B) A cellular specimen from case 1 demonstrated loosely cohesive cells with prominent vacuolated cytoplasm and eccentrically placed nuclei associated with vessels (Diff-Quik stain, × 40). (C) Case 2 demonstrated a tubuloglandular structure with cells having fairly uniform round nuclei, many of which had prominent nucleoli (Diff-Quik stain, × 600). (D) Dispersed single cells, prominent vacuolization of the cytoplasm with mildly pleomorphic round nuclei, and occasional binucleated cells were noted in case 1 (Papanicolaou stain, × 200).

Table 2. Cytomorphologic Features of MASC
FeatureCase 1Case 2Case 3Case 4Case 5Case 6
  1. Abbreviations: FISH, fluorescence in situ hybridization; H & E, hematoxylin and eosin; MASC, mammary analogue secretory carcinoma; Pap, Papanicolaou; ND, not done.
Smears available2 Pap and 2 Diff-Quik4 Pap1 H & E1 Diff-Quik3 Pap, 4 Diff-Quik, 1 H & E1 Pap and 1 Diff-Quik
Cellular arrangementSingle cellsSingle cellsSingle cellsSingle cellsSingle cellsSingle cells
 Papillary groups with transgressing vesselsPapillary groups with transgressing vesselsPapillary groups with transgressing vesselsSmall loose clustersPapillary groups with transgressing vesselsTight and loose clusters
     Small loose clusters 
Cytoplasmic featuresAbundantAbundantAbundant eosinophilicAbundantModerate eosinophilicAbundant
 Finely granularFinely granularFinely granularFinely granularFinely granularFinely granular
 Prominent vacuolization with occasional large vacuolesOccasional multivacuolatedOccasional multivacuolatedOccasional small vacuolesMultivacuolated with occasional large vacuolesProminent vacuolization with occasional large vacuoles
Nuclear atypiaModerateModerateMildMildMildModerate
Naked nucleiAbsentOccasionalProminentProminentOccasionalOccasional
Extracellular materialAbundant mucinAbundant mucinNo mucinNo mucinMucin presentMucin present
   Dense granular eosinophilic debrisOccasional metachromatic sometimes globular materialOrangeophilic globular debris 
S-100 proteinPositiveNegativeNDNDNDPositive
ETV6 FISHRearranged in 46 of 67 analyzed cells (68.7%)Rearranged in 10 of 11 analyzed cells (90.9%)NDNDNDRearranged in 55 of 60 analyzed cells (91.7%)
Original cytology diagnosisSalivary gland papillary neoplasmLow-grade epithelial neoplasmBenign salivary gland epitheliumLow-grade salivary gland neoplasmLow-grade neoplasmMASC
Figure 2.

Additional images of mammary analogue secretory carcinoma cytomorphology are shown on smears. (A) Case 1 demonstrated cells in loose clusters with multiple small to medium-sized vacuoles with abundant cytoplasm. Occasional cells were found to have a very plasmacytoid appearance when the vacuoles were absent. Extracellular material comprised of amorphous mucin was present within the background (Diff-Quik stain, × 200). (B) Case 6 demonstrated small clusters of tumor cells showing moderate to abundant finely granular cytoplasm with round uniform nuclei with small dark nucleoli. An occasional monovacuolated cell resembled a signet ring cell with the nucleus pushed to the periphery (Papanicolaou stain, × 600). (C) Loosely cohesive cells with abundant eosinophilic cytoplasm with subtle small vacuoles in some cells were noted in case 3 (H & E stain, × 200). (D) Case 2 showed a sheet of disorganized cells with prominent single vacuoles in the cytoplasm and mild nuclear pleomorphism, prominent nucleoli, and mild nuclear membrane abnormalities (Papanicolaou stain, × 600).

Figure 3.

Mammary analogue secretory carcinoma (MASC) tumor cells were found to have similar morphology on cell block preparations compared with smears. (A) A papillary structure with a fibrovascular core lined by tumor cells with abundant eosinophilic cytoplasm was noted in case 1 (H & E stain, × 200). (B) Mucin production was observed in case 6 (mucicarmine, × 400). (C) Although nearly all MASC tumors are positive for S-100 protein at the time of surgical resection, sampling issues in fine-needle aspiration can lead to S-100 protein negativity on cell block preparations (case 2, × 200). (D) ETV6 fluorescence in situ hybridization analysis of cytology cell block material was successful, with approximately 68.7% of analyzed cells in case 1 demonstrating gene rearrangement (white arrows indicate ETV6 translocation-positive cells with 1 split red and green signal) (× 600).

Cell block material was available for 3 cases (cases 1, 2, and 6). Sections from the cell blocks showed small tissue fragments with tumor cells arranged in small clusters with microcystic architecture resembling gland formation and papillary structures (Fig. 3A). Again, tumor cells had abundant finely granular and eosinophilic cytoplasm and prominent vacuolization. S-100 protein was positive in cases 1 and 6 but negative in case 2 (Fig. 3C). Mammaglobin was performed on the cell block preparation obtained from case 1 and was found to be positive.

Histologic Features

Cases 1 through 5 were diagnosed as MASC after surgical resection. All were uninodular/cystic and were comprised of tumor cells with abundant finely granular and vacuolated eosinophilic cytoplasm (Fig. 4). The predominant architectural patterns varied in these 5 cases and included tumors with predominantly papillary growth within a large cystic space (cases 1 and 5), unilocular cystic tumors with focal mural nodules demonstrating microcystic growth (case 2), predominantly microcystic tumors with areas of papillary growth (case 3), and predominantly solid tumors (case 4). Mitotic activity was rare to absent and nuclear grade was moderate in all tumors, with the majority of cells demonstrating medium-sized nucleoli. Necrosis and angiolymphatic invasion were absent but perineural invasion was identified in case 4. Lymphoid stroma was prominent in case 3. All tumors demonstrated mucin production. Two small incidental Warthin tumors were also found to be present in case 1. Evidence of possible prior FNA was observed in most tumors with stromal fibrosis and/or cholesterol granulomas.

Figure 4.

Histology of mammary analogue secretory carcinoma after tumor resection is shown. Tumor cells with abundant finely granular and vacuolated cytoplasm were observed. In this case, the nuclear grade appeared to be higher on the resection specimen from case 1 with slight nuclear size variation and occasional eosinophilic nucleoli (H & E stain, × 400). Inset: S-100 protein staining can be patchy, with focal areas being weak to negative (Case 2; × 100).

Immunohistochemical staining for S-100 protein on the surgically excised tumors was positive in 4 cases (cases 1, 2, 3, and 4) and was not performed in case 5. Case 6 was not excised because the patient refused further treatment despite a diagnosis of MASC made on the FNA specimen. It is interesting to note that in case 2, which was negative for S-100 protein on the cytology cell block, focal areas of the tumor were also found to be negative for S-100 protein (Fig. 4inset). Mammaglobin was found to be positive in 2 cases (cases 3 and 4) and was not performed in the remaining cases.

Detection of ETV6 Gene Rearrangement on Cytology Cell Block Material

After the diagnosis of MASC was made on the resection specimens from cases 1 and 2, retrospective ETV6 FISH was performed on cell block material as proof of principle for this method to allow the definitive diagnosis of MASC on cytology. For case 6, ETV6 FISH was performed in a “real-time” fashion while the case was still active. Two cases had an adequate number of cells with which to perform a full count (cases 1 and 6). In case 2, only 11 cells were analyzed, making this sample inadequate; however, of these 11 cells, 10 demonstrated an ETV6 translocation. In summary, of the 3 cytology samples with available cell block material, 2 cases were found to be positive for the ETV6 gene rearrangement (46 of 67 analyzed cells [68.7%] in case 1 and 55 of 60 analyzed cells [91.7%] in case 6), whereas case 2 was considered to be inadequate for analysis; 10 of 11 analyzed cells (90.9%) did demonstrate an ETV6 translocation (mean number of positive cells for all 3 cases, 83.8%) (Fig. 3D).


With the rapidly increasing recognition of MASC on resection specimens and the importance of FNA in the surgical management of patients with salivary gland tumors, it is appropriate to characterize the cytomorphologic characteristics of this new entity. The ability to recognize MASC on FNA can help to guide surgical management. In contrast to AciCC, MASC tends to demonstrate an increased frequency of lymph node metastases.[3] Therefore, in institutions that do not routinely perform neck dissections for patients with AciCC, the diagnosis of MASC on cytologic material should alert the clinicians to possible lymph node metastases and the possible need for neck dissection in some patients. In the current study, we examined the cytomorphologic features of 6 cases of molecularly confirmed MASC.

MASC has a characteristic cytomorphologic appearance although one that is perhaps not entirely distinctive. The cases in the current series were cellular, demonstrating arborizing papillary cell fragments with fibrovascular cores and a modest number of single cells in the background. Cytologically, they had a characteristic vacuolated, granular, and (in some staining preparations) eosinophilic cytoplasm. As such, these tumors tend to invoke the differential diagnostic considerations in the oncocytic category of salivary gland neoplasms.

Differential Diagnosis and Pitfalls

The major differential diagnostic considerations with MASC and key differentiating features by cytology are listed in Table 3. Similar to surgical resection specimens, AciCC is also a major differential diagnostic consideration on FNA specimens. Before the description of MASC, the majority of these tumors were categorized as AciCC or adenocarcinoma/cystadenocarcinoma, not otherwise specified.[6, 7] Although classic AciCC is recognized by its basophilic zymogen granules,[8] zymogen granule-poor AciCC with more prominent nonspecific ductal cells or vacuolated cytoplasm can pose a significant challenge.[6, 7] Architecturally, AciCC and MASC both can demonstrate a spectrum of growth patterns and therefore can have a similar cellular arrangement on smears, including papillary structures. Some subtle distinguishing clues (when present) to delineate MASC from AciCC are prominent extracellular and intracellular mucin and a greater variation in the size of the cytoplasmic vacuoles. Clinical features such as anatomic location and the sex of the patient can be helpful because an extraparotid site or male sex favors MASC over AciCC.[3]

Table 3. Key Cytologic Differential Diagnoses of MASC
DiagnosisKey Cytomorphologic FeaturesKey Ancillary Testing Features
  1. Abbreviations: DOG-1, discovered on GIST-1; MAML2, mastermind-like protein 2; MASC, mammary analogue secretory carcinoma; PASD, periodic acid-Schiff diastase.
Benign salivary glandAcinar and ductal cells, low cellularity, more cohesive 
Benign oncocytic neoplasms [oncocytoma, oncocytic cystadenoma, Warthin tumor]Lack vacuolated cytoplasm, more cohesiveAntimitochondrial antibody positive, S-100 negative
Acinic cell carcinomaUsually lacks mucinPASD-positive cytoplasmic granules, DOG-1 strong, S-100 weak, mammaglobin negative
Mucoepidermoid carcinomaEpidermoid differentiationp63 positive, MAML2 translocation, S-100 negative
Salivary duct carcinomaHigh-grade nuclei and necrosisAndrogen receptor positive, S-100 negative

One potential pitfall in cytology specimens from AciCC is mistakenly interpreting aspirates as normal salivary gland tissue. This same challenge exists with MASC, as was demonstrated in case 3 in the current study, because MASC with papillary tumor clusters and transgressing vessels can resemble benign salivary gland acini and excretory ducts. A helpful feature is that tumors tend to be more cellular with more single cells in the background compared with nonneoplastic lesions. An aspirate with variations in acinar group size, cytoplasmic vacuolation, and single dyshesive cells favors a diagnosis of MASC over normal salivary gland tissue.

MEC, particularly the oncocytic variant, enters the differential diagnostic considerations because of the abundant eosinophilic cytoplasm and mucin production characteristic of MASC. Again, the distinction between these 2 entities on FNA smears may be subtle but cell clusters in MEC usually do not have a prominent papillary or arborizing appearance such as that observed in MASC. When papillae are present in MEC, they are typically bordered by mucocytes. Furthermore, although both tumors produce mucin, the mucocytes in MEC tend to be univacuolar, resembling goblet cells, whereas MASC tumor cells typically are multivacuolated, although large single vacuoles have been noted in some MASC tumor cells. Epidermoid or squamoid differentiation, if present, supports MEC as the diagnosis.

Salivary duct carcinoma (SDCA) can exhibit an eosinophilic vacuolated appearance and also produce mucin. In the majority of cases, SDCA is easily distinguished from MASC because of its higher cytonuclear grade. There is often a background of necrosis and a neutrophilic tumor diathesis with SDCA that is not observed in MASC. Occasionally, SDCA with more bland morphologic features does occur, which could make the distinction more challenging in some cases. In these cases, the apocrine phenotype of SDCA with size variation in the cells and prominent nucleoli is still evident and can be of help. Occasionally, particularly in cell blocks, decapitation secretions can be identified, thereby supporting a diagnosis of SDCA.

On the other end of the spectrum, MASC may mimic benign oncocytic neoplasms such as oncocytoma, oncocytic cystadenoma, and Warthin tumor. In patients with Warthin tumor, a prominent lymphoid stroma is characteristic but it is well known that such a stroma is not specific for this diagnosis as it may be in some cases of MEC and AciCC. Although none of the cases of MASC reported in the current study was found to demonstrate a prominent lymphoid background on aspirate smears, lymphoid stroma has been described in surgical resections of MASC.[6] These oncocytic tumors can have papillary cell clusters or arborizing tissue fragments on FNA smears. Distinguishing features are the presence of a vacuolar appearance and more prominent cell dyshesion in MASC. Mucin production can be reported in benign oncocytic lesions; however, it is not as prominent as it is in MASC.

One of the previously reported cases of MASC with associated FNA cytology gave the initial impression through cytology of a pleomorphic adenoma with oncocytic features.[4] Although this would likely be a rare consideration, the discohesive single tumor cells of MASC entrapped in mucin may mimic the myxoid stroma of pleomorphic adenoma. Careful examination of the more cellular elements should help to exclude this differential diagnostic consideration if the architectural and cytologic features of MASC discussed above are noted.

Canalicular adenoma and polymorphous low-grade adenocarcinoma may occasionally enter into the differential diagnosis for tumors occurring at minor salivary gland sites. The cytologic features of these tumors are not well established but should be easily distinguished from MASC because the latter generally demonstrates characteristic abundant vacuolated cytoplasm that should not be noted in canalicular adenoma or polymorphous low-grade adenocarcinoma.[9] One caveat with these 2 rare considerations is that they share S-100 positivity with MASC; therefore, morphologic features are especially important in this case.

Ancillary Studies

Given the considerable overlap in the differential diagnostic considerations of MASC, it is often difficult to arrive at a definitive diagnosis based on FNA aspirate smears alone. Initial ancillary studies to help in making a more precise classification can include simple histochemical stains such as periodic acid-Schiff after diastase (PASD) and/or mucicarmine stains, either on blank aspirate smears or cell block preparations. PASD can be used to highlight zymogen granules, which would indicate AciCC rather than MASC. One cautionary note is that, occasionally, the microvacuolar droplets of mucin in MASC can mimic the granularity of AciCC on PASD stains. Although prominent mucicarmine reactivity may argue against AciCC, this may not serve to distinguish MASC from MEC or even SDCA. Immunohistochemical markers that may refine the diagnosis further include S-100 protein, p63, DOG-1 (discovered on GIST-1), mammaglobin, and androgen receptor. Unlike the majority of other entities in the differential diagnosis, MASC tends to be positive for S-100 protein, which on occasion can resolve the differential diagnosis with just a single immunohistochemical stain. S-100 protein staining in MASC is generally intense but heterogeneous staining can lead to negative results on FNA material (as presented in case 2 in the current study). In such cases, other immunochemical markers can be of value. Unlike AciCC, MASC is usually strongly positive for mammaglobin and AciCC is now known to be far more strongly positive for DOG-1 than the other entities in the differential diagnosis.[10] Whereas MASC may demonstrate some p63 immunoreactivity,[11] it will not be as prominent as in MEC. Although both MASC and SDCA are positive for mammaglobin, SDCA is also positive for androgen receptor.

Ultimately, 1 singular feature of MASC that is of greatest value in reaching a definitive diagnosis on FNA is the ETV6-NTRK3 translocation. In the 3 cases in the current study for which there was available cell block material, we were able to confirm the presence of the ETV6 gene rearrangement. In 1 case, despite the presence of only 11 analyzable cells, 10 were found to harbor an ETV6 gene rearrangement. In another case, FISH analysis of the cell block preparation allowed for a definitive diagnosis without surgical excision. Thus, when cytologic features indicate the possibility of MASC, FISH analysis is a feasible and valuable ancillary test. Positivity for the translocation confirms malignancy, and also may allow the surgeon to consider neck dissection upfront because MASC has been shown to have a slightly higher propensity for lymph node metastases compared with AciCC.[3] Although MASC is the only known primary salivary gland tumor to harbor an ETV6 translocation, detection of the ETV6 translocation could also be explained by a rare metastatic secretory carcinoma.

MASC has a characteristic arborizing, oncocytic, and vacuolated appearance on FNA specimens but often demonstrates considerable morphologic overlap with other tumor types such as AciCC, MEC, SDCA, and oncocytoma. The use of ancillary studies may refine the diagnosis further and could include PASD, S-100 protein, and ETV6 FISH analysis. Cytopathologists should add MASC to the differential diagnosis of oncocytic neoplasms of the salivary gland. With increasing awareness of this entity and the use of ancillary testing, a definitive diagnosis is highly feasible before surgical excision is performed.


We thank Dr. Irwin Nash in the Department of Pathology at the Hospital of St. Raphael in New Haven, Connecticut for kindly providing a cytology smear for our review. We also thank Kathleen Cieply and the University of Pittsburgh Medical Center In Situ Laboratory for their assistance in performing the ETV6 fluorescence in situ hybridization analysis.


No specific funding was disclosed.


The authors made no disclosures.