Is DOG1 really useful in the diagnosis of salivary gland acinic cell carcinoma? - A DOG1 (clone K9) analysis in fine needle aspiration cell blocks and the review of the literature

Oncocytoid Salivary Tumors: Differential Diagnosis and Utility of Newly Described Immunohistochemistry

BACKGROUND

Oncocytoid salivary tumors include several entities such as oncocytoma, Warthin tumor, secretory carcinoma (SC), salivary duct carcinoma (SDC), acinic cell carcinoma (AciCC), oncocytic mucoepidermoid carcinoma (OMEC), intraductal carcinoma, and epithelial myoepithelial carcinoma (EMC). This review investigates the differential diagnosis of oncocytoid salivary tumors and explore the role of newly described immunostains as valuable tools for their diagnosing and potentially guiding treatment options.

METHODS

We assess the utility of incorporating new immunohistochemical markers in routine practice to aid in diagnosing oncocytoid salivary tumors and potentially provide treatment options.

RESULTS

In SDC, AR and Her2 immunostains are utilized as diagnostic tools and biomarkers for selecting patients who might benefit from Androgen-deprivation therapy (ADT) and HER2-targeted therapy. Furthermore, nuclear Pan-Trk immunostaining can aid in diagnosing SC. Additionally, NR4A3 immunostaining has been shown high sensitivity and specificity in identifying AciCC in both surgical and cytologic specimens. Similarly, RAS Q61R mutant-specific immunostaining, detected in EMC, may offer a cost-effective diagnostic marker for this tumor. Although further studies are required to evaluate the role of BSND, this marker has been reported to be positive in Warthin tumor and oncocytoma, aiding in differentiating them from other oncocytoid tumors, particularly OMEC. In addition, BRAFV600E mutant-specific immunostaining can serve as a diagnostic and potentially therapeutic marker for oncocytic intraductal carcinoma in mutation positive cases.

CONCLUSION

Oncocytoid salivary tumors may have overlapping morphologies, posing diagnostic challenges for pathologists. Recently described immunohistochemical markers may offer valuable tools for diagnosing and potentially guiding treatment options for these tumors.

NR4A3 Fluorescence In Situ Hybridization Analysis in Cytologic and Surgical Specimens of acinic cell carcinoma

BACKGROUND

Acinic cell carcinoma (AciCC) may pose a diagnostic challenge, particularly on small biopsies and fine needle aspiration (FNA) because of its variable histology including potential high grade transformation and its mimickers. Immunoreactivity with circumferential membranous staining for DOG1 can support the diagnosis of AciCC but is not entirely specific. A novel rearrangement t(4;9)(q13;q31) leading to upregulation of nuclear receptor subfamily 4 group A member 3 (NR4A3) has been described in AciCC, is potentially detectable by Fluorescence in situ hybridization (FISH) and may be useful in the evaluation for AciCC.

METHODS

Using NR4A3 Dual Color Break Apart Probe (Zytovision, Germany) FISH was performed on AciCCs from three large academic institutions. NR4A3 rearrangement was defined as positive signal patterns in 15% of tissue interphase nuclei.

RESULTS

52 AciCCs including 47 resections and 5 FNAs (including 5 paired FNA/resections) were analyzed. 5 non-AciCC salivary gland tumors and 2 sialadenitis cases were used as controls. 8 (15%) (8/52) AciCCs failed FISH testing. FISH was positive in 23 AciCCs (sensitivity 59%, 23/39) with 100% concordance between five matched resection/FNAs (three were positive for FISH and two were negative). FISH was negative in all non-AciCCs (specificity: 100%, 0/7).

CONCLUSION

NR4A3 FISH has a sensitivity of 59% and specificity of 100% in detecting AciCC which suggests that NR4A3 rearrangement-driven upregulation is a recurrent, specific oncogenic event in AciCC, consistent with prior results. 100% concordance between matched FNA/resection samples validate its potential utility on cytology samples.

NR4A3 Immunostain Is a Highly Sensitive and Specific Marker for Acinic Cell Carcinoma in Cytologic and Surgical Specimens

OBJECTIVES

Salivary gland acinic cell carcinoma (AciCC) has recognizable cytomorphologic features that can overlap with benign and malignant entities, creating a diagnostic challenge. AciCC harbors a t(4;9) translocation increasing nuclear receptor subfamily 4 group A member 3 (NR4A3) expression, detectable by immunohistochemistry (IHC) on surgical resection (SR). NR4A3 IHC cytology data are limited. Here, we examine NR4A3 IHC on smears, cell blocks (CBs), and SRs of AciCC and its mimickers.

METHODS

Our cohort comprised AciCC (including high-grade transformation), secretory carcinoma, mucoepidermoid carcinoma (MEC), Warthin tumor, pleomorphic adenoma (PA), cellular PA, carcinoma ex-PA, oncocytic carcinoma, oncocytoma, and nodular oncocytosis. NR4A3 IHC (Santa Cruz Biotechnology and Origene antibodies) was positive if more than 5% tumor cells showed nuclear staining.

RESULTS

Among CBs, 90% of AciCC cases and none of the mimickers expressed NR4A3. Among SRs, 100% of AciCC cases showed diffuse NR4A3, whereas one high-grade MEC expressed focal NR4A3. Concordance was 95% with two antibody clones. Sensitivity, specificity, positive predictive value, and negative predictive value were 90%, 100%, 100%, and 94.7% for CBs and 100%, 98.8%, 92.3%, and 100% for SRs, respectively. NR4A3 immunostaining was demonstrable on smears from an AciCC case.

CONCLUSIONS

NR4A3 IHC can be a robust diagnostic tool to identify AciCC, especially for cytology specimens.

Cytopathology of acinic cell carcinoma: A study of 50 cases, including 9 with high-grade transformation

BACKGROUND

Although largely readily recognizable in tissue sections, acinic cell carcinoma (ACC) remains diagnostically problematic in fine-needle aspiration (FNA) cytopathology. The authors undertook an analysis of a large series of ACC aspirates, including acinic cell carcinoma with high-grade transformation (ACC-HGT).

METHODS

The authors searched their cytopathology files for ACC cases with histopathologic confirmation. FNA biopsy was performed according to standard techniques.

RESULTS

Fifty FNA biopsy cases of ACC (including 36 of parotid origin [72%]) from 41 patients (female to male ratio, 1.4:1; age range, 23-84 years; average, 54 years) met the study inclusion requirements. Primary neoplasm aspirates were most common (72%), and they were followed by recurrent tumors (16%) and metastases (12%). A precise cytologic diagnosis was made for 64%. Three of 9 ACC-HGT cases (33%) were correctly interpreted as such; 98% of conventional ACC cases were correctly graded as low-grade. With the Milan classification system, 74% fit into the malignant category. Ancillary testing was performed for only 36%. Conventional ACC had moderately to highly cellular smears; monotonous cells in aggregates and single forms; rounded nuclei; and microvacuolated, finely granular, oncocyte-like, or nonspecific cytoplasm. ACC-HGT smears contained larger nuclei, high nuclear to cytoplasmic ratios, coarse nuclear chromatin, and a loss of cytoplasmic granules/vacuoles.

CONCLUSIONS

A correct diagnosis of ACC via FNA biopsy was made in almost two-thirds of the cases. With the Milan classification, 84% of the cases would have been classified as malignant or suspicious for malignancy. An absence of conventional serous acinar cell morphology in some cases as well as an absence of ancillary immunohistochemistry testing in almost two-thirds of the cases prevented even better diagnostic performance.

Acinic Cell Carcinoma of the Breast: Report of a Case With Immunohistochemical and Next-Generation Sequencing Studies

Acinic cell carcinoma of the breast is a rare subtype of triple-negative breast cancer that recapitulates the appearance of tumors seen in salivary glands. We present the case of a 42-year-old woman with an irregular, nontender mass above the left nipple during routine obstetric appointment at 24 weeks gestation. She was subsequently diagnosed with triple-negative invasive ductal carcinoma of the left breast, Nottingham grade 3, via core needle biopsy. She was treated with neoadjuvant therapy (doxorubucin and cyclophosphamide) antenatally and paclitaxel in the postpartum period followed by left mastectomy with sentinel node biopsy. The carcinoma in the mastectomy specimen showed a spectrum of morphologic patterns with immunohistochemistry revealing strong positivity for alpha-1-antichymotrypsin, epithelial membrane antigen (EMA), lysozyme, and S100. The histomorphology paired with the immunoprofile led us to the diagnosis of acinic cell carcinoma. We retrospectively performed immunostains in the core biopsy specimen, which demonstrated GATA-3 and DOG-1 positivity. Next-generation sequencing of the postneoadjuvant specimen using a 70-gene panel revealed 2 single-nucleotide variant (SNV) mutations: tumor protein 53 (TP53) (c.747G>T) SNV mutation and rearranged during transfection (RET) (c.2899G>A) SNV mutation.

Evaluation of NR4A3 immunohistochemistry (IHC) and fluorescence in situ hybridization and comparison with DOG1 IHC for FNA diagnosis of acinic cell carcinoma

BACKGROUND

Acinic cell carcinoma (AcCC) is diagnostically challenging on fine-needle aspiration because it can mimic several other neoplasms or even normal acinar tissue. Immunopositivity for DOG1, especially circumferential membranous staining, can support the diagnosis of AcCC but is not entirely specific, and it is prone to technical and interpretive challenges on small specimens. NR4A3 (nuclear receptor subfamily 4 group A member 3) translocation and nuclear NR4A3 overexpression were recently described in the majority of AcCCs. Here, the authors evaluate the performance of NR4A3 immunohistochemistry (IHC) and NR4A3 break-apart fluorescence in situ hybridization (FISH) on cell block preparations and compare them with DOG1 IHC in distinguishing AcCC from other entities in the differential diagnosis.

METHODS

The authors identified 34 cytology cell blocks with lesional cells, including 11 specimens of AcCC (2 of which derived from 1 patient and showed high-grade transformation) as well as 2 secretory carcinomas, 7 salivary duct carcinomas, 4 mucoepidermoid carcinomas, 3 oncocytomas, 3 renal cell carcinomas, and 6 specimens containing nonneoplastic salivary gland tissue. NR4A3 IHC, DOG1 IHC, and NR4A3 FISH were attempted for all cases.

RESULTS

NR4A3 IHC had 81.8% sensitivity and 100% specificity for AcCC, whereas NR4A3 FISH had 36.4% sensitivity and 100% specificity, although 4 cases (3 mucoepidermoid carcinomas and 1 salivary gland tissue sample) could not be analyzed because of low cellularity. Notably, no normal acinar tissue specimens showed NR4A3 positivity by IHC or FISH. In addition, DOG1 IHC had 72.7% sensitivity and 92% specificity.

CONCLUSIONS

NR4A3 IHC is highly specific for the diagnosis of AcCC and is more sensitive than DOG1 IHC and NR4A3 FISH. In addition, NR4A3 IHC performance is not improved by the inclusion of DOG1 IHC. Finally, NR4A3 positivity resolves the perennial problem of distinguishing AcCC from normal acinar tissue.

Diagnostic Utility of Immunohistochemical Expressions of IMP3 Versus DOG1 and p63 in Salivary Gland Tumors

OBJECTIVE

The diverse site of origin and classification complexity of salivary glands tumors increase difficulties in their diagnosis. This study aimed to evaluate the specificity and diagnostic ability of immunohistochemical expressions of IMP3 versus DOG1 and p63 in cases of such tumors.

MATERIAL AND METHOD

Thirty paraffin-embedded salivary gland tumors were obtained from the Pathology Department Archive. Their diagnosis was confirmed. The specimens were then re-classified and evaluated using the IMP3, DOG1 and p63 immunohistochemical markers.

RESULTS

There were 8 pleomorphic adenoma (PA), 12 mucoepidermoid carcinoma (MEC) and 10 adenoid cystic carcinoma (ADC) cases. All 12 MECs (100%) were IMP3 positive, while 30% of ADCs and only 25% of PAs were positive for IMP3. There was a statistically significant relationship between salivary gland tumors and IMP3 immunostaining (P =0.03). As regards to DOG1 results, 12.5% of PAs showed variable luminal positive immunostaining and 40% of ADCs showed weak luminal and abluminal immunostaining while 16.7% of MEC showed cytoplasmic staining. On the other hand, all ADCs (100%) showed moderate p63 reactivity in the nuclei of abluminal cells. All MEC cases (100%) were also p63-positive, showing a strong diffuse nuclear reactivity. A statistically significant relationship was noticed between salivary gland tumors and p63 immunostaining (P < 0.05).

CONCLUSION

IMP3 is more sensitive for diagnosis of MEC than ADC. p63 is statistically significant in diagnosing salivary gland tumors (MEC and ADC). On the other hand, DOG1 staining is not sensitive in diagnosis of studied malignant salivary gland tumors, limiting its diagnostic utility.

Primary Pulmonary Acinic Cell Carcinoma: A Clinicopathological Study of 6 Cases and Literature Review

Primary pulmonary acinic cell carcinoma (ACC) is rare. The clinicopathological features are not identical to that of classic ACC that leads to misdiagnosis. In this article, we summarized the clinicopathological features of 25 such cases, including 6 cases in this series and additional 19 cases in the literature. Pulmonary ACCs showed an overwhelming solid growth pattern. The neoplastic cells had eosinophilic granular and clear cytoplasm in most cases and displayed basophilic cytoplasm in only 4 cases. Intratumoral fibrous septa, mitotic figure, necrosis, and psammoma bodies were observed in some cases. Prominent nuclear atypia and perineural invasion might suggest high-grade transformation, metastasis, and recurrence. The tumor cells were strongly positive for CK8/18 and negative for TTF-1, p63, S-100, mammaglobin, MUC5b, MUC5ac, and DOG1. CK7 was exclusively positive for neoplastic cells with ductal differentiation. Of the 25 included cases, 10 cases were initially misdiagnosed. The tumor was prone to involve the right bronchus. The patient outcome was favorable. The accurate diagnosis of primary pulmonary ACC relies on comprehensive evaluation of histological and immunohistochemical features and realization of the difference from classic ACC.

Characterisation of DOG-1 Expression in Salivary Gland Tumours and Comparison with Myoepithelial Markers

DOG1 is an established diagnostic marker for gastrointestinal stromal tumours (GIST), but has been reported in salivary gland tumours (SGT) as an acinar and intercalated duct marker. However, its specificity and distribution is not well established. The aim of this study was to evaluate the diagnostic utility of DOG-1 expression in SGT in addition to comparing it with myoepithelial markers. Normal salivary tissue and SGT (n = 184) were examined for expression of DOG1 and a range of myoepithelial markers. SGT included: acinic cell carcinoma (ACC, n = 15), secretory carcinoma (SC, n = 9), pleomorphic adenoma (PA, n = 49), carcinoma ex-PA (Ca ex-PA, n = 11), adenoid cystic carcinoma (AdCC, n = 20), polymorphous adenocarcinoma (PAC, n = 6), myoepithelioma (n = 6), myoepithelial carcinoma (MC, n = 2), basal cell adenoma (BCA, n = 14), canalicular adenoma (CA, n = 19), mucoepidermoid carcinoma (MEC, n = 11), oncocytoma (n = 2), adenocarcinoma NOS (AdNOS, n = 4), basal cell adenocarcinoma (BCAC, n = 2), salivary duct carcinoma (SDC, n = 3) and papillary cystadenocarcinoma (PCAC, n = 1). Normal acini and ACC (14/15) showed strong luminal DOG1 staining; SC were largely negative with only focal expression in 3/9 cases. Luminal staining was seen in PA (14/49), PAC (4/6), Ca ex-PA (4/11) and AdCC (6/20). 8/11 MEC showed luminal and/or mucous cell staining. No staining was seen in myoepithelioma, MC, CA, adNOS and BCAC. BCA showed strong staining of myoepithelial cells in some cases (5/14). Variable myoepithelial DOG1 staining was seen in PA, Ca ex PA, BCA, SDC and PCAC which was not as consistent as myoepithelial markers such as calponin, p63 and αSMA. Absence of DOG1 can differentiate ACC from SC, but staining is variable in PA, PLGA and Ca ex-PA. Myoepithelial staining in some tumours but not in normal gland suggests a wider distribution in SGT than originally envisaged.