Differentiation and the cytomorphology of salivary gland tumors with specific reference to oncocytic metaplasia

Salivary Gland Intraductal Carcinoma: How Do 183 Reported Cases Fit Into a Developing Classification

Salivary gland intraductal carcinoma (IDC) is a very uncommon group of neoplasms. Many names, variations in diagnostic criteria, and newly observed molecular findings (including NCOA4 :: RET , TRIM27 :: RET , HRAS point mutations, and PIK3CA pathway alterations) have generated further confusion in being able to recognize and categorize this group of tumors. Different histologic appearances and patterns of growth suggest there is more than one tumor category, with intercalated duct, apocrine, oncocytic, and hybrid features seen. Frankly destructive invasion further complicates the category, as the name "intraductal" would suggest an "in situ" neoplasm. Recent evidence on fusion-positive IDC demonstrates the same molecular underpinnings in both the ductal and the myoepithelial cells, which aids in further separating these tumors. This article summarizes the historical group of 183 neoplasms classified under the umbrella of IDC and highlights the unique histologic, immunohistochemistry, and molecular features that may further guide nomenclature standardization and harmonization.

Prominent oncocytic metaplasia in pleomorphic adenoma: A potential diagnostic pitfall

Pleomorphic adenoma (PA) is the most common salivary gland tumor. The cytological features of PA are well recognized, and its diagnosis is straightforward in most cases. Some metaplastic changes in PA are well known; however, occurrence of oncocytic metaplasia in PA is very rare. In this report, we describe the first cytological case of prominent oncocytic metaplasia in PA identified based on immunocytochemical analysis. We report the case of a 62-year-old Japanese female who presented with swelling of the left neck region. A fine-needle aspiration cytologic examination was performed followed by surgical resection. The Papanicolaou smear revealed the presence of discohesive neoplastic cells in a myxoid background. These neoplastic cells had a relatively rich, granular cytoplasm, and round nuclei with moderate pleomorphism. Initial cytodiagnosis revealed carcinoma ex PA (CXPA). Immunocytochemical analysis showed that abundant mitochondria were present in the cytoplasm of these neoplastic cells. Histopathological examination of the resected tumor demonstrated proliferation of oncocytic neoplastic cells within a myxoid material and the presence of conventional PA components. A final diagnosis of prominent oncocytic metaplasia in PA was made. Oncocytic metaplasia showed nuclear atypia and pleomorphism; therefore, CXPA, which presents with severe nuclear atypia and necrotic background, must be differentiated from oncocytic metaplastic PA. Recognition of oncocytic metaplasia in PA is important for correct diagnosis.

Nodular oncocytic hyperplasia: Can cytomorphology allow for the preoperative diagnosis of a nonneoplastic salivary disease?

BACKGROUND

Nodular oncocytic hyperplasia (oncocytosis) of the salivary glands is a benign process that does not inherently require surgical excision. However, cytologic findings in fine-needle aspiration (FNA) of oncocytosis cases have not been well characterized previously, limiting preoperative identification.

METHODS

All available cases of oncocytosis with corresponding FNA specimens were identified from the pathology archives of 3 academic institutions. Clinical, cytologic, and histologic findings were tabulated for all cases.

RESULTS

Twelve cases of oncocytosis were identified from 11 patients, including 11 parotid FNA specimens and 1 submandibular FNA specimen. On the original diagnoses, 6 specimens were classified as benign, 4 as atypical, and 2 as nondiagnostic. Oncocytosis was listed in the differential diagnosis in only 1 case. Among diagnostic aspirates, 8 demonstrated low cellularity and 2 demonstrated moderate cellularity. All 10 cases demonstrated oncocytic cells in small to medium groups, with single cells in just 1 case. Spindled and squamous morphology were each noted in 3 cases. Four cases demonstrated cystic change and 1 showed background mucin without goblet cells. No necrosis or mitoses were observed.

CONCLUSIONS

Although oncocytosis demonstrates some overlap with Warthin tumor and oncocytoma, it lacks the diagnostic findings specific to oncocytic salivary gland malignancies such as salivary duct carcinoma, acinic cell carcinoma, mammary analog secretory carcinoma, and mucoepidermoid carcinoma. Despite current limitations in the understanding of oncocytic salivary gland lesions, the presence of a paucicellular specimen comprised of small groups of oncocytic cells should raise the possibility of oncocytosis in the differential diagnosis and can favor it in elderly patients with multiple salivary nodules. Cancer Cytopathol 2017;125:627-34. © 2017 American Cancer Society.

Oncocytic carcinoma of the salivary gland with thymoma: A case report and review of the literature

Oncocytic carcinoma (OC) arising in the salivary gland is a very rare tumor with only 32 previously reported cases. In this report, we describe a novel case of oncocytic carcinoma with associated thymoma, which arose in the left parotid gland of a 66-year-old male with a history of a painless left parotid mass for 1 year. Oncocytes are large, polygonal cells that are characterized by marked cellular atypia, frequent mitoses, wide eosinophilic granular cytoplasm, a central nucleus and a prominent nucleolus. The follow-up data showed no evidence of recurrence and the patient is in a good health 20 months after the surgery. In the current case, the patient had not only OC but also thymoma, which is exceedingly rare and may represent the first documented case in the literature.

Multifocal adenomatous oncocytic hyperplasia of the parotid gland

Multifocal adenomatous oncocytic hyperplasia (MAOH) is a non-neoplastic lesion that is classified as oncocytosis. MAOH is a rare entity of the parotid gland and accounts for approximately 0.1% of salivary gland lesions. Here, we report a case of MAOH of the parotid gland. The patient was a 71-year-old woman who presented with discomfort at the left side of her neck. Fine-needle aspiration cytology of the parotid gland revealed a loose sheet-like cluster of round to polygonal cells with granular cytoplasm against a hemorrhagic background. The cells had round to oval, centrally located nuclei with granular chromatin and without distinct nucleoli. Histologically, the lesion was formed of many variable-sized nodules, comprising oncocyte-like cells with small round nuclei and eosinophilic granular cytoplasm that was positive for mitochondrial antibodies. The diagnosis of MAOH is difficult to make by cytology alone, because the findings overlap with those of other oncocytic lesions. In particular, the cytological findings of MAOH have not been sufficiently reported to date. A correlation of cytology and histology was expected.

Oncocytic meningioma: a case report and review of the literature

Oncocytic meningioma is an uncommon variant of meningioma, with only 20 reported cases to date, that is histologically characterized by the presence of neoplastic cells with granular eosinophilic cytoplasm rich in mitochondria. We present the clinicopathological features of a case of oncocytic meningioma in a 49-year-old Chinese female, along with a literature review. Brain computed tomography and magnetic resonance imaging demonstrated a slightly hyperintense mass located in the right frontal region and attached to the dura. In addition, it was homogeneously enhanced following contrast administration. She underwent gross total surgical resection of the tumor and adjacent dura. Grossly, the well-demarcated, nonencapsulated mass had a solid and tan-white appearance with soft and rubbery consistency. The lesions were composed primarily of sheets, nests, and cords of large polygonal bland cells with finely granular eosinophilic cytoplasm rich in mitochondria. Mitotic figures were rare, and necrosis was absent. There was no infiltration of the dura or brain cortex. Immunohistochemical staining revealed that the neoplastic cells were positive for vimentin, epithelial membrane antigen, antimitochondrial antibody, and progesterone receptor, whereas MIB-1 stained only approximately 1% of the tumor cells. This is the first known report of an oncocytic meningioma arising in a Chinese patient. The patient was followed for 19 months without any evidence of metastasis or recurrence.

A perspective of comparative salivary and breast pathology. Part I: microstructural aspects, adaptations and cellular events

This is the first part of a review comparing the pathology of salivary and mammary glands. Here, less obvious similarities and differences in functional histology and their influences on pathology are examined with emphasis on myoepithelial cells, stromal components, analogues of mucosa-associated lymphoid tissue, steroid receptors, and intraparenchymal cells of monocytic lineage. Particular cell phenotypes (oncocytic, apocrine, neuroendocrine and clear) are critically evaluated and responses to atrophy, infarction and fine-needle aspiration biopsy procedures are highlighted together with aspects of metaplasia, regeneration, ageing and microcalcification. Areas of controversy or uncertainty which may benefit from further investigations are also discussed.

CT features of parotid gland oncocytomas: a study of 10 cases and literature review

Oncocytomas of the salivary glands are rare benign epithelial tumors which occur most commonly in the parotid gland. The aim of our study was to characterize the clinical-radiologic-pathologic spectrum of parotid oncocytomas in a series of 10 cases seen in our institution between January 2003 and November 2008. The CT features of parotid oncocytomas in the largest imaging series of this rare but important benign lesion include a well-defined enhancing tumor with a "deformable" appearance when large, and a non-enhancing curvilinear cleft or cystic component. These CT findings are potentially helpful in distinguishing these benign lesions from other parotid tumors in clinical scenarios that preclude surgical resection or when biopsy results are non-diagnostic. Further studies are advocated to validate the specificity and positive predictive value of these imaging features.

High-grade oncocytic mucoepidermoid carcinoma of the minor salivary gland origin: a case report with immunohistochemical study

An oncocytic mucoepidermoid carcinoma arising from the minor salivary gland origin is extremely rare. We report on a 44-year-old man with a high-grade oncocytic mucoepidermoid carcinoma originating in the minor salivary gland of the posterior mandible. All tumor cells showed the expected pattern of immunoreactivity, with positive results for the antimitochondrial antibody and p63, and negative results for the androgenic receptor antibody. Microscopically, the tumor was considered to be a high-grade carcinoma in the grading systems of the Armed Forces Institute of Pathology and Brandwein. The patient underwent a partial mandibulectomy, and the lesion was reconstructed with a right fibula osteofasciocutaneous flap under general anesthesia. The patient is currently under long-term follow-up.

Oncocytic mucoepidermoid carcinoma: clinicopathologic description in a series of 12 cases

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. Oncocytic MEC (OMEC) has been rarely reported with previous cases suggesting they are largely cystic low-grade neoplasms with a favorable prognosis. The differential diagnosis of OMEC includes numerous oncocytic/"oncocytoid" neoplasms. Some are benign while others are aggressive. Recent evidence suggests that p63 is a reliable marker in the diagnosis of conventional MEC but has not been explored in OMEC. We searched the archives of various institutions for examples of OMEC to re-appraise the grade, and to evaluate p63 immunohistochemistry as a tool to separate OMEC from its potential mimics. A total of 12 cases were identified. There were 6 males and 6 females with an age range of 30 to 79 years. Most occurred in the parotid (9) with 1 each in the sublingual gland, hard palate and neck. They showed minimal cystic content and were infiltrative and solid tumors spanning all grades. All tumors had focal mucin production and were composed almost exclusively of oncocytic cells with 2 cases demonstrating conventional MEC areas. All 6 cases tested showed the majority of oncocytic cells staining with p63 in a diffuse pattern, demonstrating its utility in the diagnosis of OMEC. Of the 6 cases with follow-up information, 1 case had local recurrence 8 years after the initial surgery. Three cases showed skin or bone invasion. None had lymph node/distant metastases. In summary, OMEC behaves as a low-grade tumor, and is diffusely positive for p63, which may aid in its differential diagnosis.

Orbital conjunctival dermoid cyst with oncocytic differentiation

A dermoid cyst of conjunctival origin ("conjunctivoid") is a rare variant that has conjunctival nonkeratinizing squamous epithelium and goblet cells, instead of keratinizing squamous epithelium of epidermal origin with epidermal appendages. We report a case of a 65-year-old man with a chronic orbital mass, a conjunctival dermoid that was found to have the unusual histopathologic finding of oncocytic differentiation. This is an infrequent benign chronic change in glandular cells characterized by the accumulation of vast numbers of intracellular mitochondria. Occasionally, oncocytic cellular change occurs in malignant tumors, and so complete excision of such lesions is recommended.

Oncocytic change in pleomorphic adenoma: molecular evidence in support of an origin in neoplastic cells

BACKGROUND

Cells with oncocytic change (OC) are a common finding in salivary glands (SGs) and in SG tumours. When found within pleomorphic adenomas (PAs), cells with OC may be perceived as evidence of malignancy, and lead to a misdiagnosis of carcinoma ex pleomorphic adenoma (CaExPa).

AIM

To describe a case of PA with atypical OC, resembling a CaExPa. A genomewide molecular analysis was carried out to compare the molecular genetic features of the two components and to determine whether the oncocytic cells originated from PA cells, entrapped normal cells, or whether these cells constitute an independent tumour.

MATERIALS AND METHODS

Representative blocks were immunohistochemically analysed with antibodies raised against cytokeratin (Ck) 5/6, Ck8/18, Ck14, vimentin, p63, alpha-smooth muscle actin (ASMA), S100 protein, anti-mitochondria antibody, beta-catenin, HER2, Ki67, p53 and epidermal growth factor receptor. Typical areas of PA and OC were microdissected and subjected to microarray-based comparative genomic hybridisation (aCGH). Chromogenic in situ hybridisation (CISH) was performed with in-house generated probes to validate the aCGH findings.

RESULTS

PA cells showed the typical immunohistochemical profile, including positivity for Ck5/6, Ck8/18, Ck14, vimentin, ASMA, S100 protein, p63, epidermal growth factor receptor and beta-catenin, whereas oncocytic cells showed a luminal phenotype, expression of anti-mitochondria antibody and reduced beta-catenin staining. Both components showed low proliferation rates and lacked p53 reactivity. aCGH revealed a similar amplification in both components, mapping to 12q13.3-q21.1, which was further validated by CISH. No HER2 gene amplification or overexpression was observed. The foci of oncocytic metaplasia showed an additional low-level gain of 6p25.2-p21.31.

CONCLUSION

The present data demonstrate that the bizarre atypical cells of the present case show evidence of clonality but no features of malignancy. In addition, owing to the presence of a similar genome amplification pattern in both components, it is proposed that at least in some cases, OC may originate from PA cells.

Oncocytic mucoepidermoid carcinoma of parotid gland origin

This article reports 3 cases of oncocytic mucoepidermoid carcinoma of the parotid gland and compares them with 9 cases from the literature with emphasis on clinical behavior, treatment, and recurrence rate. The tumor occurs most often in the middle-aged to elderly, with a decided predilection for the parotid gland. All three oncocytic mucoepidermoid carcinomas from the Armed Forces Institute of Pathology series were low grade with extensive oncocytic change. Treatment modalities consisted of superficial parotidectomy, total parotidectomy, or total parotidectomy. The mean follow-up interval was 5.5 years. Only one case from the literature, a high-grade mucoepidermoid carcinoma, recurred. Results of this study indicate that the parotid gland oncocytic mucoepidermoid carcinoma behaves in a fashion similar to typical mucoepidermoid carcinoma, with prognosis dependent on clinical stage, histopathologic grade, and adequacy of treatment. Recognizing the spectrum of oncocytic differentiation in salivary gland tumors will serve to establish appropriate diagnoses and treatment.

Oncocytic tumor in myoepithelioma arising from the grossopalatine gland

Oncocytoma or oncocytic change in salivary glands normally occurs in old patients and mostly in the parotid gland, but those arising from the grossopalatine gland in young patients are extremely rare. The present case shows that oncocytic ductal structures were observed in myoepithelioma, consisting of spindle, plasmacytoid or epithelioid cells. The oncocytic tumor contained large amounts of eosinophilic granular cytoplasm and small nuclei.