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Abstract Background N-Nitrosomorpholine (NMO) is one of the most common N-nitroso compounds. An oncocytic transformation has been demonstrated in renal tubules of NMO-treated rats. In our study, we aimed to investigate the potential transformation of oncocytic cells in 6 endocrine organs, i.e., thyroid, adrenal and pituitary glands, pancreas, testis, and bone, of NMO-exposed rats. Methods Thirty male rats were born and raised. Fifteen of them were given a single dose of 320 mg NMO per kg body weight, dissolved in drinking water, by a gavage tube. At the end of 52 weeks, the animals in both series were killed. Right after the killing, 6 different endocrine organs (hypophysis, thyroid, pancreas, adrenal gland, bone [femur], and testicles) of each animal were excised. Results There was no evidence of oncocytic cell development in the control group. In contrast, oncocytes were observed in 8 out of 13 NMO-treated rats: 2 in the adrenal sections, 1 in the thyroid sections, 3 in the pituitary sections, and 2 in the pancreas sections. Thesticle and bone sections were completely normal. Conclusions We showed that NMO induced an oncocytic change in pancreas, thyroid, pituitary, and adrenal glands. To date, no identified specific environmental risk factors that lead to an oncocytic transformation in endocrine glands have been reported previously. Given the increasing prevalence of endocrine-disrupting chemicals in the environment, personal care products, manufactured goods, and food sources, there is a need to advance our understanding of the pathological mechanisms underlying oncocytosis in endocrine organs.

Background: N-Nitrosomorpholine (NMO) is one of the most common N-nitroso compounds. An oncocytic transformation has been demonstrated in renal tubules of NMO-treated rats. In our study, we aimed to investigate the potential transformation of oncocytic cells in 6 endocrine organs, i.e., thyroid, adrenal and pituitary glands, pancreas, testis, and bone, of NMO-exposed rats. Methods: Thirty male rats were born and raised. Fifteen of them were given a single dose of 320 mg NMO per kg body weight, dissolved in drinking water, by a gavage tube. At the end of 52 weeks, the animals in both series were killed. Right after the killing, 6 different endocrine organs (hypophysis, thyroid, pancreas, adrenal gland, bone [femur], and testicles) of each animal were excised. Results: There was no evidence of oncocytic cell development in the control group. In contrast, oncocytes were observed in 8 out of 13 NMO-treated rats: 2 in the adrenal sections, 1 in the thyroid sections, 3 in the pituitary sections, and 2 in the pancreas sections. Thesticle and bone sections were completely normal. Conclusions: We showed that NMO induced an oncocytic change in pancreas, thyroid, pituitary, and adrenal glands. To date, no identified specific environmental risk factors that lead to an oncocytic transformation in endocrine glands have been reported previously. Given the increasing prevalence of endocrine-disrupting chemicals in the environment, personal care products, manufactured goods, and food sources, there is a need to advance our understanding of the pathological mechanisms underlying oncocytosis in endocrine organs. [ABSTRACT FROM AUTHOR]

Background: Oncocytes are a component of many metaplastic and neoplastic lesions throughout the head and neck area, primarily originating in salivary/seromucinous glands and the thyroid gland. In addition, other lesions can contain cells that mimic oncocytes (pseudo-oncocytes); these can be of epithelial or non-epithelial origin. Methods: Review article. Results: Oncocytic metaplasia is common in seromucinous glands throughout the upper aerodigestive tract, most notable in the oral cavity, nasopharynx and larynx. The main oncocytic salivary gland neoplasms are Warthin tumor and oncocytoma. Infarction of Warthin tumor may lead to recognition difficulties. Oncocytic subtypes of mucoepidermoid carcinoma and intraductal carcinoma have morphologic and immunohistochemical features that allow distinction from major oncocytic entities. Oncocytic thyroid tumors include adenoma, carcinoma (follicular, papillary and medullary), along with poorly differentiated tumors. Oncocytic papillary sinonasal and middle ear tumors must be distinguished from low grade adenocarcinomas. Pseudo-oncocytic entities include paraganglioma, Langerhans cell histiocytosis, giant cell tumor, rhabdomyoma, and metastatic tumors. Conclusions: Correct diagnosis of oncocytic head and neck lesions requires a knowledge of the spectrum of possible entities, their characteristic sites of occurrence, architecture, histomorphology, and immunohistochemistry. Oncocytic subtypes of several newly described entities are now recognized. Both epithelial and non-epithelial mimics of oncocytes exist. The molecular features of oncocytic tumors can be helpful in their diagnosis and understanding their pathogenesis. [ABSTRACT FROM AUTHOR]

Abstract Aims This study retrospectively investigated the morphological, immunohistochemical and molecular genetic features of papillary renal neoplasm with reverse polarity (PRNRP), a recently described renal tumor. Methods and results Eleven cases of PRNRP were collected, and 16 cases of type I and 9 cases of type II papillary renal cell carcinoma were included as a control series. Pathological features were evaluated based on HE staining and immunohistochemistry. KRAS exon 2 and BRAF V600E mutations were detected by Real-time PCR and Sanger sequencing. Fluorescence in situ hybridization was conducted for identification of chromosomal abnormalities. Hemosiderin deposition was found in a small amount of tumor cells in 6 cases. Multifocal or patchy necrosis (5/11), small focal invasion of the pseudocapsules or renal parenchyma (6/11), and breakthrough of renal capsule with nerve invasion (1/11) were revealed, inconsistent with the previous view that the tumor lacks necrosis and intercellular hemosiderin. Immunohistochemical staining (diffusely positive for CK7 and GATA3, negative for CD117 and vimentin, and negative to weakly positive for P504S) and high frequency of KRAS mutations in exon 2 (9/10) supported the identification and inclusion of our cases. Chromosome 7 trisomy (1/7), chromosome 17 trisomy (0/7) and chromosome Y deletion (0/5 male patients) were seldom detected in this tumor. All patients were alive without metastasis or recurrence at the end of the follow-up. Conclusion Our findings may highlight the possibility of a low malignant potential of this emerging entity. We suggest that the tumor be classified as a novel renal cell tumor subtype independent of papillary renal cell carcinoma.

Oncocytes are epithelial cells having abundant eosinophilic cytoplasm. The presence of oncocytes in salivary glands pose a diagnostic challenge since they can be present in lesions ranging from non-neoplastic, benign to malignant. FNAC is a simple procedure which can aid in the pre-operative diagnosis of these lesions. This study is an eight year retrospective study in which salivary gland aspiration cytology cases having oncocytic cells and with available corresponding histopathology were included. These slides were reviewed for features like cellularity, presence of oncocytic cells, glandular elements, squamoid cells, nuclear atypia, mitosis, lymphoid tissue, necrosis. Twenty cases were included in the study. The mean age of presentation was 60 years showing male preponderance with parotid gland being the most common site of involvement. Concordant diagnosis on cytology and histopathology was seen in 16 cases and discordance was seen in 4 cases. All the discordant cases were reported as benign on cytology but on histopathology they were labelled as acinic cell carcinoma, squamous cell carcinoma, mucoepidermoid carcinoma and an intraparotid lymph node respectively. Review of discordant cases showed subtle findings like ill-formed acini, cytoplasmic vacuolation, goblet cells and dysplastic foci raising suspicion of a different diagnosis. The potential areas of pitfall and cause of discrepancy have been discussed in this study. It is crucial to be aware of the spectrum of lesions in which oncocytes are seen, to enable an accurate diagnosis on cytology. Careful evaluation of smears for subtle clues can minimize errors. [ABSTRACT FROM AUTHOR]

Aims: This study retrospectively investigated the morphological, immunohistochemical and molecular genetic features of papillary renal neoplasm with reverse polarity (PRNRP), a recently described renal tumor. Methods and results: Eleven cases of PRNRP were collected, and 16 cases of type I and 9 cases of type II papillary renal cell carcinoma were included as a control series. Pathological features were evaluated based on HE staining and immunohistochemistry. KRAS exon 2 and BRAF V600E mutations were detected by Real-time PCR and Sanger sequencing. Fluorescence in situ hybridization was conducted for identification of chromosomal abnormalities. Hemosiderin deposition was found in a small amount of tumor cells in 6 cases. Multifocal or patchy necrosis (5/11), small focal invasion of the pseudocapsules or renal parenchyma (6/11), and breakthrough of renal capsule with nerve invasion (1/11) were revealed, inconsistent with the previous view that the tumor lacks necrosis and intercellular hemosiderin. Immunohistochemical staining (diffusely positive for CK7 and GATA3, negative for CD117 and vimentin, and negative to weakly positive for P504S) and high frequency of KRAS mutations in exon 2 (9/10) supported the identification and inclusion of our cases. Chromosome 7 trisomy (1/7), chromosome 17 trisomy (0/7) and chromosome Y deletion (0/5 male patients) were seldom detected in this tumor. All patients were alive without metastasis or recurrence at the end of the follow-up. Conclusion: Our findings may highlight the possibility of a low malignant potential of this emerging entity. We suggest that the tumor be classified as a novel renal cell tumor subtype independent of papillary renal cell carcinoma. [ABSTRACT FROM AUTHOR]

Abstract Oncocytic adenolipoma is a rare tumor to occur in the salivary gland, which can present as a giant neck mass. Until now,

Rationale: Oncocytic mucoepidermoid carcinoma (OMEC) is a rare variant of mucoepidermoid carcinoma (MEC). The parotid gland is the most common site of OMEC, whereas intraoral OMEC is infrequent. Patient Concerns: A 55-year-old male presented with an asymptomatic mass at the palate for 20 years. Diagnosis: Incisional biopsy showed classic MEC. Treatment: The patient underwent partial maxillectomy under general anaesthesia. The excised specimen revealed sheets of oncocytes additional to the tumour cells found in the incisional biopsy. Additional special stain and immunohistochemical stain confirmed the diagnosis of OMEC. Outcomes: The patient was followed up for 3 years with no recurrence. Take-away Lessons: The diagnosis of OMEC needs to be differentiated from other salivary gland tumours containing oncocytes. Moreover, the conventional grading system applied to OMEC may not correlate with their behavior and may need further review. [ABSTRACT FROM AUTHOR]

Oncocytic adenolipoma is a rare tumor to occur in the salivary gland, which can present as a giant neck mass. Until now, <20 such cases are reported. We report this rare case for surgeons to consider it as one of the differential diagnoses. [ABSTRACT FROM AUTHOR]

Introduction: Bronchopulmonary carcinoids are low-grade tumors for which the standard treatment is surgical resection. We retrospectively evaluated the surgical outcomes. Methods: Thirteen patients underwent surgical resection for them at our institution between January 2005 and December 2016. We collected their clinicopathologic data to evaluate surgical outcomes. Results: The 13 patients comprised seven men and six women. Complete resection was performed in all cases. All the tumors were typical carcinoids, including one oncocytic carcinoid which showed highest fluorodeoxyglucose (FDG) uptake (SUVmax 45.7). The 5-year overall survival rates were 100%. The only patient with oncocytic carcinoid developed recurrence of liver metastasis 49 months after the primary lung resection. The metastasis showed low FDG uptake (SUVmax 2.8) and its histology was typical carcinoid and not oncocytic carcinoid. Conclusion: Surgical outcomes in our patients were favorable. In oncocytic carcinoid, metastatic site may have a radiologic and histologic appearance different from the primary tumor. [ABSTRACT FROM AUTHOR]

Abundant calcifications and clear-cell change may occur in oncocytic thyroid adenoma (OTA). We aimed to report the features of a case of OTA peculiar by the presence of extensive calcifications and of a clear-cell component. The OTA was detected on a right thyroid lobectomy specimen. Clear-cell change was observed in 15%-20% of the cells. Numerous, focally confluent psammomatoid calcifications, resulting in macrocalcifications, were identified. The nodule cells, uni- or multinucleated oncocytes, including those with clear cytoplasm, expressed heterogeneously TTF1, S100 protein, Bcl2, CD10, as well as CD138 and CD56. Lipid-droplet markers adipophilin and TIP47 were also expressed. In conclusion, we report a rare type of OTA, peculiar by the presence of numerous psammomatoid calcifications and of macrocalcification and by the presence of clear-cell change. Heterogeneity in membrane CD56 and/or CD138 expression as well as cytoplasmic heterogeneity of Bcl2 and lipid-droplet marker TIP47 might be relevant for calcification and clear-cell change, requiring further investigation. [ABSTRACT FROM AUTHOR]

Sialolipoma, a rare tumor of the salivary gland, is a recently described variant of salivary gland lipoma. Oncocytic sialolipoma was first described by Pusiol et al. in 2009. We report the case of an oncocytic sialolipoma of the submandibular gland in a 43-year-old female. Excision of the tumor was performed with preservation of the submandibular gland. The tumor had a thin, fibrous capsule and consisted of abundant adipose tissue, an oncocytic nodule, and scattered normal glandular structures surrounded by adipose tissue. Four cases of sialolipoma of the submandibular gland, including the present case, were reviewed. All 4 tumors were developed on the right submandibular glands, with a composition of adipose tissue as high as that of sialolipoma of the parotid gland; in contrast to previous reports, three cases were in females. As newly described tumor type, care should be taken to distinguish oncocytic sialolipoma from other salivary gland neoplasms such as simple lipoma, pleomorphic adenoma, or oncocytoma.

Intrahepatic cholangiocarcinoma (ICCA) comprises 10% of all cholangiocarcinoma (CCA). It can be divided into three macroscopic subtypes, the least common of which is characterized by intraductal growth and believed to be more amenable to good outcomes with surgical resection compared to other ICCA. Recently, the rare finding of oncocytic differentiation has been described in this subtype and termed «intraductal oncocytic papillary neoplasm» (IOPN), but it remains unclear if the presence of oncocytes confers a different tumor behavior. We present the eighth reported case of IOPN, which to our knowledge, is the first such case that, due to its location and vascular compromise, required orthotopic liver transplantation (OLT). This case adds to the little that is known about the behavior of IOPN and supports the observation that resection, or OLT when resection is not possible, is a valid treatment option.

Extramedullary hematopoiesis (EMH) is a phenomenon in which hematopoietic cells are found in sites other than the bone marrow. It is usually observed in the liver and spleen but may occasionally be found within solid tumors. The current case report presents a 69-year-old female patient who presented with a renal cyst. Histopathological examination following surgical removal of the cyst revealed a lining of oncocytic- and chromophobe-type cells with capsular invasion and a mass forming EMH with evident bone trabeculae within the cyst wall. Circulating hematopoietic stem cells in the blood and their colonization within tissues is discussed in the present case report, emphasizing certain types of renal cell carcinoma. [ABSTRACT FROM AUTHOR]

DU145 human prostate carcinoma cells are typically poorly differentiated and contain only scantily distributed organelles. However, among numerous tumor cells randomly examined by electron microscopy out of in vitro cultivation, a peculiar, rare oncocyte-like cell type has been observed whose nucleus appears to be of small dimension and with a cytoplasm almost entirely filled with often distorted mitochondria. A few small, dispersed lysosomal bodies, small cisterns of the endoplasmic reticulum and a few glycogen patches can be found among highly osmiophilic contrasted, cytosolic spaces filled by innumerable ribonucleoproteins. The excessive population of mitochondria may have arisen from a more populated tumor cell type wherein the altered mitochondria are found to appear burgeoning into a spherical-like size progeny crowding the tumor cells. Literature cited between 1950 and the present suggests that this rare, oncocytic, benign prostatic tumor cell type is likely appear epigenetically, stemming from an original secretory cell, which is confirmed by the origin of the cell line originally maintained as cell line out of a brain metastatic, adenocarcinoma niche. [ABSTRACT FROM AUTHOR]

Beginning the study of chronic pathologic changes in pancreas of hamsters experimentally infected with Trypanosoma cruzi Vic strain, hepatocyte metaplasia was observed in one animal from infected group. This is the first report of oncocytes in Chagas' disease, which could be due to aberrant regenerative response to pancreas inflammatory process.

Hürthle cells (HCs) and HC change, along with the frequently employed synonyms "oncocytes/oncocytic change" or "oxyphils/oxyphilic change," are not infrequently described on fine-needle aspiration biopsy (FNAB) reports of thyroid lesions. The description of HCs on FNAB reports may cause significant concern to the clinician; however, placing the finding in the appropriate clinical context may alleviate some anxiety. Not all oxyphilic cells are true HCs and not every aspirate containing HCs is or should be considered equivalent to an HC neoplasm (HCN). There are many benign thyroid lesions associated with HCs or HC change. For clinicians, it may be difficult to discern the significance of these findings and to determine an appropriate course of action. A skilled and experienced cytopathologist is invaluable in discriminating the subtle features that distinguish these lesions from those warranting a more aggressive approach. The diagnosis of HC carcinoma relies on histopathologic scrutiny and evidence of capsular and/or vascular invasion or metastasis to lymph nodes or distant organs. Many investigators have sought clinical, radiographic, cytological, genetic, and other factors to attempt to discriminate pre-operatively between benign and malignant HCNs. To date, none have been definitively proven to be reliable. For now, because of the inability to determine the benign or malignant nature of such neoplasms based on cytology alone, a surgical approach is warranted. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to define the clinicopathologic features and outcome of the oncocytic variant of papillary thyroid carcinoma (OVPTC) with a review of the literature. Methods: Twenty-three patients with OVPTC over a 10-year period were studied. Demographic, clinical, and histopathcilogic features and outcome data were analyzed retrospectively, Results: Seventeen women and 6 men, ages ranging from 20 to 76 years (95% confidence interval, 43.0 to 54.48), were studied. Cervical lymph node involvement was found in 43.4% of the patients. Most of the recurrences were associated with thyroid masses greater than 2 cm in diameter. Evaluation of the overall survival data by the Kaplan-Meier method revealed that most recurrences took place earlier than 30 months, and the majority of patients (74%) were well, with no evidence of disease, up to 78 months after the last treatment. All of the OVPTC cases presented as nonencapsulated tumors, and 78.2% demonstrated extrathyroid strumal invasion. Conclusions: OVPTC is a unique variant of papillary thyroid carcinoma that has distinctive clinicopathologic features. Since OVPTC is often associated with local invasion and may involve cervical lymph nodes, it may require more extensive surgery than classic papillary thyroid carcinoma. [ABSTRACT FROM AUTHOR]

Abstract: An oncocyte is a cell containing an abundant amount of deeply eosinophilic finely granular cytoplasm, rounded nuclei, and variable presence of nucleoli in conventional hematoxylin-eosin–stained sections. In the head and neck, a small number of lesions are constructed overwhelmingly of oncocytes; a larger number of nononcocytic lesions composed of cells that imitate this morphology are also encountered. Correlating the fine-needle aspiration cytology and histology of both oncocytic and oncocyte-like neoplasms can assist in avoiding interpretive pitfalls among these lesions. [Copyright &y& Elsevier]

Herein is described a unique renal cell tumor with previously unreported morphological and immunohistochemical features. The patient was a 78-year-old Japanese man. A huge left renal tumor was found on ultrasound during evaluation of left abdominal distention. The tumor was macroscopically characterized by a non-infiltrative border, pale yellow to grayish color, foci of hemorrhage and partial edematous change. Histologically the tumor had an extensive small tubular growth pattern often with papillary fronds mainly composed of oncocytic cells with deeply eosinophilic granular cytoplasm. Clear vacuolated cells were scattered among the oncocytic cells. The present case had an unusual immunohistochemical profile for all known types of renal cell tumors, but both the oncocytic cells and the clear vacuolated cells were strongly immunoreactive for α-methylacyl-coenzyme A racemase. It is concluded that the tumor may be a candidate for a rare variant of papillary renal cell carcinoma. Further cases having similar features are awaited for a definitive classification of this tumor as a previously undescribed tumor type. [ABSTRACT FROM AUTHOR]

A malignant melanoma was diagnosed in an axillary lymph node of a 49-year-old man. The tumor was examined by electron microscopy and was found to be composed of large oncocytic cells, filled with abundant mitochondria. No primary tumor could be identified on the skin or within internal organs. Approximately 2 years after the initial diagnosis, the patient presented with malignant melanoma in an axillary lymph node on the contralateral side. The second tumor also expressed the same oncocytic phenotype, favoring the common origin of both tumors. These data illustrate that oncocytic melanomas may retain their oncocytic phenotype during metastatic dissemination. [ABSTRACT FROM AUTHOR]

A case is reported herein of intrahepatic cholangiocarcinoma (ICC) with multicystic, mucinous appearance and oncocytic change. Because of liver dysfunction, a 73-year-old woman was hospitalized in early October 2003. She was diagnosed as having ICC of the right hepatic lobe with occlusion of the hilar and perihilar bile ducts by imaging examination. Extended right lobectomy was performed but the patient died of liver failure on the next day. In surgically resected specimens, the tumor (3 × 3 cm) was mainly located in the right lobe, and tumors infiltrated along the biliary tree as well as invading into the adjacent hepatic parenchyma. The tumor mass had a sponge or honeycomb appearance. Microscopically, these tumors were composed of multiple microcysts filled by abundant mucin and lined by micropapillary adenocarcinoma cells. Their cytoplasm was acidophilic, appearing as an oncocyte, and carcinoma cells were positive for mitochondrial antigen in addition to biliary cytokeratins. There were no ovarian-like stromas around these cystic tumors, and communication of the biliary lumen with these carcinomatous cysts was not evident, thus different from biliary mucinous cystadenocarcinoma and intraductal papillary neoplasm of the liver. This is the third case of multicystic mucinous ICC and the present case might have been derived from intrahepatic peribiliary glands. [ABSTRACT FROM AUTHOR]

Oncocytic papillary carcinoma with lymphoid stroma (Warthin-like tumour) of the thyroid: a distinct entity with favourable prognosis Aims: We report the clinicopathological and immunohistochemical characteristics of 12 cases of a recently recognized entity, oncocytic papillary thyroid carcinoma (PC) with lymphoid stroma (Warthin-like tumour). Methods and results: The cases were retrieved from the surgical pathology files of our departments. There were 11 female patients and one male patient; they ranged in age from 45 to 85 years (mean 64.2 years). The immunohistochemical profile demonstrated positivity of tumour cells for cytokeratins, thyroglobulin, Leu-M1 and anti-mitochondrial antigen. S100 protein-positive stromal dendritic/Langerhans cells were uniformly present. Polymerase chain reaction, in situ hybridization, and immunohistochemistry for Epstein–Barr virus (EBV) detection revealed no significant positive signal. MIB-1 labelling index was low, compatible with that of ‘classical’ PC. Conclusions: Warthin-like tumour is a rare variant of PC, occurring predominantly in elderly women. Its histological features are distinct and well recognizable, differentiating this tumour from a more aggressive tall-cell variant of PC. The apparent indolent behaviour seems to be consistent with the presence of dendritic/Langerhans cells and with low proliferative activity. A possible role of EBV in pathogenesis of this lesion was not proven. Further studies are necessary to determine the prognosis and metastatic potential of this neoplasm. [ABSTRACT FROM AUTHOR]

Oncocytes are characterized by a remarkable number of mitochondria as demonstrated by electron microscopy. Oncocytomas are very rare tumors that are usually benign and typically occur in the parotid gland. Oncocytic carcinomas are exceedingly rare in the salivary glands. We describe a 69-year-old Japanese man with an oncocytic carcinoma of the submandibular gland. We reviewed 38 articles describing oncocytic carcinoma of the head and neck that included clinicopathologic features. Oncocytic carcinomas appear to arise from benign oncocytomas, or may also arise de novo. In oncocytic carcinoma of the head and neck, the presence of distant, rather than local lymph node, metastasis is the most important prognostic indicator. [ABSTRACT FROM AUTHOR]

A case of ovarian adenocarcinoma mainly composed of oncocytes was studied by light and electron microscopy. Oncocytes, characterized by granular and eosinophilic cytoplasm by light microscopy possessed numerous mitochondria at the ultrastructural level. These oncocytes were classified into two types: typical and condensed oncocytes. Typical oncocytes seemed to be active, whereas condensed oncocytes were thought to be involved in a degenerative process. The two types of cells showed a close similarity to oncocytes in other organs (e.g., thyroid, parathyroid and salivary glands). This appears to be the first report of an ovarian oncocytic tumor. [ABSTRACT FROM AUTHOR]

Oncocytic hyperplasia in the human labial salivary glands was sought in a series of 217 post-mortem subjects. Oncocytic change occured in 183 subjects and hyperplasia was found in 19 of those (the overall incidence being 8.8%), ranging in age from the third deacde to the ninth. The sex distribution showed a significantly greater rate in males (16 of 139 males, 11.5%; 3 of 78 females, 3.8%). Oncocytic hyperplasia occurred in the duct system, and not in the acinar regions; it was frequently seen in the interlobular and intralobular ducts. Oncocytic hyperplasia was classified into four types; focal hyperplasia of the duct wall resulting in partial thickening of the duct wall; marked hyperplasia resulting in thickening of the duct wall, extending over half of the circumference; marked hyperplasia extending to the whole duct wall and intralobular adeno-tubular hyperplasia with or without cystic dilatation. About half of the subjects with oncocytic hyperplasia showed a few hyperplastic foci in one gland. The changes increased in severity in older subjects. [ABSTRACT FROM AUTHOR]

Oncocytic carcinomas are uncommon; they represent 11% of all oncocytic salivary gland neoplasms, 0.5% of all epithelial salivary gland malignancies and 0.18% of all epithelial salivary gland tumors. A 65-year-old woman was admitted to our ENT clinic with a history of a painless left preauricular mass. No lymph node was palpable on either side of her neck. Computed tomography demonstrated a 3×3-cm solid lesion in the left parotid gland. As oncocytes and atypical cells were seen at the cytologic examination of a fine-needle aspiration biopsy, this finding suggested a malignant epithelial tumor. Total parotidectomy by preserving the facial nerve was performed. The result of the pathologic examination was oncocytic carcinoma regarding histopathologic and immunohistochemical findings and especially the invasive growth pattern. We preferred a close follow-up to an elective neck dissection, and reserved the neck dissection for a recurrence. The prognosis of oncocytic carcinomas is not well known because of their low incidence. Further investigation of the prognosis of patients with oncocytic carcinoma of the parotid gland is warranted as more cases are reported. [ABSTRACT FROM AUTHOR]

Our understanding of neoplasia is evolving at a rapid pace in these exciting times, where recent molecular pathology advances are reinforcing and fine tuning morphological divisions and classification. Thyroid gland neoplasia in general, and Hürthle-cell neoplasms in particular, are no exception in the current era of histopathology-molecular biology paradigm. In this review paper, we discuss the rationale that led pathologists in the past to separate Hürthle-cell neoplasms into its own dedicated diagnostic category, and provide an algorithmic approach to the differential diagnosis of oncocytic lesions of the thyroid. This review will also shed light on the current WHO classification of Hürthle-cell neoplasms in light of molecular advances that justify histopathologic distinctions., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A rare case of ovarian adenocarcinoma with extensive oncocytic differentiation is presented. Light and electron microscopy examination and a specific stain for mitochondria (chromotrope-alcian blue) confirmed the diagnosis. The tumour cells revealed abundant granular and eosinophilic cytoplasm containing a large number of mitochondria. The tumour had a malignant infiltrative pattern and cellular atypia. [ABSTRACT FROM AUTHOR]