A case of tumor-to-tumor metastasis of cutaneous malignant melanoma

We report a case of tumor-to-tumor metastasis of a cutaneous malignant melanoma to a synchronous thyroid Hurthle cell carcinoma. A 42-year-old male underwent a biopsy of right inguinal lymphadenopathy which showed metastatic melanoma. The primary lesion was identified on his right posterior leg, and staging workup discovered a synchronous left thyroid lobe nodule concerning for a follicular neoplasm. He underwent excision of the primary melanoma, right inguinal lymphadenectomy, and total thyroidectomy. The resected thyroid contained a 6.6-cm, well-encapsulated left-sided nodule, red-brown in color and homogenous in consistency, with areas of focal hemorrhage and no grossly identifiable calcification. Microscopically, large tumor cells with distinct cell borders were present, with deeply eosinophilic and granular cytoplasm, large nuclei with prominent nucleoli, and loss of polarity consistent with oncocytes. A microscopic single focus of vascular invasion was identified, and a diagnosis of angioinvasive Hurthle cell carcinoma was made. Within the Hurthle cell carcinoma, multiple deposits of metastatic melanoma were seen. These findings were indicative of tumor-to-tumor metastasis of the cutaneous melanoma to the angioinvasive Hurthle cell carcinoma. Our findings show the ability of melanoma to metastasize to a pre-existing neoplasm.

Spindle cell oncocytoma of the adenohypophysis - a clinicopathological and ultrastructural study of two cases

Spindle cell oncocytoma (SCO) of the pituitary gland is a relatively recently established, very rare subtype of adenohypophysis tumours that was introduced as a distinct clinicopathological entity in the fourth edition of WHO classification of the central nervous system tumours (2007). It is non-endocrine neoplasm of the anterior pituitary that occurs in adults and usually follows a benign clinical course, corresponding to WHO grade I. Up to now, pituitary SCO have been reported occasionally and only 14 cases of SCO have been documented in the literature. Because of their rarity, the pathogenesis and natural history of these tumours have not been fully characterized. We report two additional cases of SCO occurring in females aged 63 years (Case 1) and 65 years (Case 2), who presented with pan-hypopituitarism, headache and visual field defect. In both cases, the magnetic resonance imaging showed solid sellar mass of moderate size with suprasellar extension. The clinical and radiological features suggested non-functioning pituitary macroadenomas without evidence of invasive growth. One patient presented with tumour recurrence 3 years after undergoing the previous surgical removal of tumour, which was initially misdiagnosed as schwannoma. The first tumour was removed by transsphenoidal surgery and the second one by frontal craniotomy. Histologically and immunohistochemically, both tumours displayed the features typical for SCO of the pituitary. They were composed of interwoven fascicles of spindle cells exhibiting abundant eosinophilic cytoplasm of oncocytic or granular appearance. Mitoses were rarely observed and necrosis was absent. In one case, the advanced lymphocytic infliltration was observed within neoplastic tissue. The tumour cells exhibited immunoreactivity for S-100 protein, galectin-3, vimentin and epithelial membrane antigen but they were negative for GFAP, anterior pituitary neuroendocrine markers (prolactin, growth hormone, TSH, ACTH, FSH, LH), chromogranin, synaptophysin, cytokeratin CK (AE1/AE3), smooth muscle actin, desmin, CD34 and CD68. MIB1 labeling index did not exceed 10%. Ultrastructurally, the tumour cells were rich in mitochondria with lamellar cristae. Moreover, in Case 2 some tumour cells showed a number of giant mitochondria with severely destructed internal matrix. Spindle cell oncocytoma of the anterior pituitary is often misdiagnosed entity of uncertain histogenesis. It should be considered in the differential diagnosis of various sellar-region lesions of oncocytic morphology.

Subclinical Cushing's syndrome associated with an adrenocortical oncocytoma

Oncocytoma is a neoplasm that can arise in several organs, and it has been more commonly described in the kidney, salivary gland and thyroid. Oncocytoma arising in the adrenal gland is a rare finding. Moreover, functioning adrenocortical oncocytoma is exceptionally rare. A 47-yr-old man was incidentally discovered to have a right adrenal mass. The patient had no clinical features suggestive of increased adrenal function. However, hormonal evaluation showed a disturbed cortisol circadian rhythm, supranormal urinary cortisol excretion, a low level of ACTH, and a lack of suppressibility of cortisol secretion after dexamethasone. Right adrenalectomy was performed, and this revealed a well-circumscribed dark-brown tumor that measured 2.4x2.2 cm. The tumor consisted almost exclusively of large eosinophilic and epitheloid cells whose cytoplasm was packed with eosinophilic granulations, which corresponded to the numerous mitochondria confirmed on electron microscopy. This is a rare case of subclinical Cushing's syndrome that was caused by adrenocortical oncocytoma.

Oncocytic non-functioning endocrine tumor of the pancreas

Herein is presented the case of a malignant non-functioning endocrine tumor of the pancreas with oncocytic features, and a discussion on the high incidence of malignancy in oncocytic endocrine pancreatic tumors. The patient was a 65-year-old woman who showed no paraneoplastic symptoms produced by functioning pancreatic endocrine tumors. The primary tumor was located in the body and tail of the pancreas, and had metastasized to the liver. Tumor cells were arranged in a ribbon-like or trabecular pattern and had an abundant eosinophilic cytoplasm containing numerous mitochondria and neurosecretory granules. The cytoplasm of the tumor cells was intensely stained with an antimitochondrial antigen antibody. Most tumor cells stained positively with Grimelius stain and for chromogranin A. Some tumor cells also stained for synaptophysin. However, the tumor cells negatively stained for hormones such as insulin, glucagon, somatostatin, gastrin, vasoactive intestinal peptide and pancreatic polypeptide, for serotonin, and for pancreatic enzymes such as amylase and trypsin. Analysis of 18 oncocytic pancreatic endocrine tumors, consisting of those reported previously and that in the present case, suggests that the high incidence of malignancy in oncocytic endocrine tumors is associated with the high incidence of non-functioning endocrine tumors among them, most of which are malignant.

Oncocytoma of the spinal cord causing paraplegia – a case report

STUDY DESIGN

Case report.

OBJECTIVES

To describe a rare case of oncocytoma arising from the spinal cord in a 40-year old woman.

SETTING

Republic of Korea.

METHODS

The patient's history, physical examination, radiological and pathological findings were reviewed.

RESULTS

A 40-year-old woman presented with 3-month history of low back pain. Magnetic resonance imaging revealed an intradural extramedullary mass located between L1 and L4. She refused any surgical treatment and so was discharged. At 10 days after discharge, an emergency operation was performed because of sudden paralysis in both lower extremities. The confirmed diagnosis is oncocytoma. At 4 months after surgery, the patient failed to obtain neurological recovery from complete paraplegia.

CONCLUSIONS

Since the progression of an intradural extramedullary mass that shows minor neurological symptoms can lead to complete paraplegia in a short time, close observation and early surgical decompression are necessary.

Spindle cell oncocytoma of the adenohypophysis: report of two recurrent cases

The recently described "spindle cell oncocytoma of the adenohypophysis" is a very rare and often misdiagnosed entity. A benign biologic behavior has been suggested based on the absence of recurrences with a median follow-up of 3 years. Herein, we present 2 cases of recurrent spindle cell oncocytomas. One patient is a 71-year-old woman (case no. 1) and the other a 76-year-old man (case no. 2). Recently, both underwent transsphenoidal reexploration for recurrent "pituitary adenoma." Patient no. 1 had initial surgery 11 years ago with a recurrence after 3 years that was initially stable. Ultimately, a partial resection was performed after compression of optic pathways by the tumor, and approximately 1 year later, re-resection was carried out. Patient no. 2 had initial surgery 10 years ago with recurrence and resection after 3 years. He recently presented with a large mass that involved the pituitary fossa and base of the skull, with extension into the nasopharynx and nasal cavity. The primary and recurrent lesions of both cases showed similar architecture with interlacing fascicles of spindle cells that alternated with areas of epithelioid-like cells that exhibited eosinophilic, granular cytoplasm. Neoplastic cells were positive for vimentin, S-100 protein, and epithelial membrane antigen, and negative for glial fibrillary acidic protein, chromogranin, and pituitary hormones. Increased mitotic activity was noted in 1 lesion (case no. 2), although both cases had high Ki-67 indices (18% and 20%, respectively). The ultrastructural features of both cases were characteristic with intracytoplasmic accumulations of large mitochondria. The histopathologic features of these lesions are consistent with spindle cell oncocytoma of the adenohypophysis. In summary, we are reporting 2 cases of recurrent spindle cell oncocytoma of adenohypophysis with longer follow-up than previously published cases, suggesting the possibility of a more aggressive behavior than has been initially considered.

Adrenocortical oncocytic tumors: report of 10 cases and review of the literature

Ten additional adrenocortical oncocytic tumors are presented: 2 benign oncocytomas, 4 borderline oncocytomas of uncertain malignant potential, and 4 oncocytic carcinomas. Histologically all tumors were entirely or predominantly composed of oncocytes. Immunohistochemically all tumors were immunoreactive for mitochondrial antigen mES-13. Electron microscopy was performed in 8 cases and was confirmatory of the oncocytic cell change. The morphologic parameters of the Weiss system, considered to be predictive of the biologic behavior of conventional (nononcocytic) adrenocortical tumors, are reviewed in the context of their possible application to the oncocytic tumor variant. Proposed major criteria (high mitotic rate, atypical mitoses, venous invasion) and minor criteria (large size and huge weight, necrosis, capsular invasion, sinusoidal invasion) in distinguishing malignant tumors are discussed, and definitional criteria (predominantly cells with eosinophilic and granular cytoplasm, high nuclear grade, diffuse architectural pattern) in common with all types of oncocytic tumors are outlined. The authors' proposed working rules for diagnostic categorization of oncocytic adrenocortical tumors are defined, with the presence of 1 major criterion indicating malignancy, 1 to 4 minor criteria indicating uncertain malignant potential (borderline), and the absence of all major and minor criteria indicative of benignancy. Using these criteria, the diagnosis of malignancy was straightforward in 3 of the 4 cases designated as oncocytic carcinoma (presence of at least 2 major criteria and all the minor criteria), while in 1 case the original diagnosis of benign oncocytoma was reversed to malignant following critical review of the original pathologic material after local tumor recurrence. Tumor recurrence occurred in 2 carcinomas at 8 and 20 months, respectively, and was followed in 1 case by the patient's death. The third patient expired at 6 months from unrelated causes, and the fourth patient is free of disease at the relatively short follow-up interval of 6 months. Regarding the 4 patients with borderline tumors, all are alive with no evidence of disease, with follow-up ranging from 10 to 61 months (mean 38.7 months). The 2 benign tumors have a follow-up of 25 and 30 months, respectively. Diagnostic difficulties are delineated and a complete review of the literature on this topic has also been performed.

Chromophobe renal cell carcinoma: a comparative study of histological, immunohistochemical and ultrastructural features using high throughput tissue microarray

AIMS

In some cases distinction between chromophobe renal cell carcinoma (CRCC), oncocytoma and clear cell (conventional) renal cell carcinoma (eosinophilic variant) using routine light microscopy remains problematic. The present study investigates the level of agreement in the diagnosis of CRCC, as well as the histological features most frequently used for this diagnosis by two pathologists with a special interest in renal neoplasia. The sensitivity and specificity of immunohistochemical markers in cases with overlapping histological features in the diagnosis of CRCC were also studied. Electron microscopy was performed, as a diagnostic gold standard, on all of the cases.

METHODS AND RESULTS

Thirty-two renal tumours with predominantly eosinophilic cytoplasm were reviewed in a blinded fashion by two pathologists. The diagnosis and morphological features used to render each diagnosis were tabulated. Validation of the utility of keratin 7 and 20, epithelial membrane antigen (EMA), vimentin, CD10, parvalbumin, RCC antigen, antimitochondrial antibody and Hale's colloidal iron was performed by the construction of a tissue microarray (TMA) master block. Based on histological criteria alone, overall agreement on the diagnosis of these tumours was reached in 69% of the cases, while there was total disagreement in 12%. In 59% of the cases, total agreement was reached in classifying the case as a CRCC based on histology alone. Kappa statistics for interobserver variability were calculated as only slight agreement (kappa = 0.3). The histological features most frequently associated with a diagnosis of CRCC were accentuated cell borders (87%) and a combination of hyperchromatic wrinkled nuclei (79%) and perinuclear halos (74%). The most sensitive and specific marker for CRCC was parvalbumin (sensitivity 0.91; specificity 1.0). The immunohistochemical profile of EMA+/ vimentin- was useful but had low specificity (sensitivity 0.75; specificity 0.4). CD10 had the highest sensitivity (1.0) but worst specificity (0.25) for CRCC. Keratin 7 had high sensitivity (0.83) but fairly low specificity (0.37) for CRCC. Hale's colloidal iron and the RCC antigen marker were not contributory. Finally, the antimitochondrial antibody was found to be fairly sensitive (0.83) for excluding CRCC.

CONCLUSIONS

A small but significant proportion of renal tumours with cells having eosinophilic cytoplasm cannot be classified, even by experienced pathologists, based on histology alone. In these cases it is imperative to use markers with known sensitivity and specificity for the diagnosis of CRCC.

Immunohistochemical identification of intracytoplasmic lumens by cytokeratin typing may differentiate renal oncocytomas from chromophobe renal cell carcinomas

Renal oncocytomas and chromophobe renal cell carcinomas (RCCs) share a common phenotype and both originate from the intercalated cells of the collecting duct. This makes it very difficult to differentiate between the two tumors immunohistochemically. Therefore, we studied the results of immunohistochemistry focusing on certain characteristic structures that are occasionally present in renal oncocytomas. We carried out Hale's colloidal iron staining and immunohistochemistry for various cytokeratins (cytokeratins 7, 8, 10, 10/13, 14, 18, 19 and 20, and AE1/AE3) in four oncocytomas and six chromophobe RCCs. In addition, one renal oncocytoma and one chromophobe RCC were studied using electron microscopy. Two renal oncocytomas and one chromophobe RCC were completely unstained by colloidal iron. There was no evident difference between the immunohistochemical characteristics of oncocytomas and those of chromophobe RCCs. However, in all four renal oncocytomas we identified intracytoplasmic ring-like positive reactions for some cytokeratins (at least 3 antigens of cytokeratins 7, 8 and 19, and AE1/AE3), which corresponded ultrastructurally to the intracytoplasmic lumens (ICLs). In contrast, no such structures were found in any of the chromophobe RCCs using the antibodies employed. Therefore, immunohistochemical identification of ICLs by cytokeratin typing may be useful for differentiating between renal oncocytomas and chromophobe RCCs and be more sensitive in this respect than colloidal iron staining.

Adrenocortical oncocytoma--a case report

Oncocytic tumours of adrenal gland are rare lesions with approximately twenty-five cases being documented in literature. A majority of them are nonfunctional and benign. We report a case of adrenal oncocytoma in a 44-year-old male, who underwent a laparotomy for a large mass in the abdomen, which was located above the left kidney. Routine histopathological examination was suggestive of a benign tumour with cells resembling oncocytes. However, immunohistochemistry and electron microscopy helped to confirm the diagnosis of an adrenocortical oncocytoma.

Renal oncocytosis presenting in childhood: a case report

Renal oncocytosis is a rare condition in which a spectrum of oncocytic lesions, including oncocytomas, diffusely involve the kidney. Few cases have been reported and all were in adult patients. We report here such a case in a 12-year-old girl. In addition to the unusual age at presentation, this case is remarkable for its heterogeneous tumor morphology, with some areas containing chromophobe carcinoma-like cells. Electron microscopy, immunohistochemistry, Hale's colloidal iron staining, and cytogenetics were performed to further evaluate the different morphologic areas. Our results suggest that the cells in the chromophobe carcinoma-like areas do not fulfill all the diagnostic criteria of chromophobe carcinoma. We caution pathologists in making a malignant diagnosis in such cases, especially in younger patients.

Oncocytic angiomyolipoma of the kidney: a case report

We describe a case of oncocytic angiomyolipoma composed of polygonal eosinophilic cells, that shares many features with renal oncocytoma. It was composed of alveolar structures, with accumulation of foamy histiocyte-like cells surrounding large globules of acellular, nonfibrillary, densely eosinophilic basal membrane-like substance. Immunohistochemically, there was focal reactivity for HMB45 and negativity for the epithelial markers. Oncocytic angiomyolipoma lacks the atypical features of the recently described epithelioid variant of angiomyolipoma. None of the reported cases have been associated with tuberous sclerosis.

Oncocytic adrenocortical carcinoma: a morphologic, immunohistochemical and ultrastructural study of four cases

We present the clinical, histologic, immunohistochemical, and ultrastructural findings of four cases of non-functioning oncocytic adrenocortical carcinomas. The patients' ages ranged from 39 to 71 years. There was no sex predilection. Large yellow-tan tumors (8.5 to 17.0 cm), well demarcated from the adjacent kidney, were seen with a thin rim of normal adrenal gland along one edge. One tumor invaded the inferior vena cava and extended up to the level of the right atrium, and another metastasized to bone. The other two tumors had similar morphologic features and therefore were considered carcinomas. Histologic sections of all four cases showed a diffuse proliferation of polygonal neoplastic cells with large nuclei containing prominent nucleoli and abundant granular and eosinophilic cytoplasm. Occasional mononuclear and binucleated giant cells were noted in one case. There were rare mitotic figures (less than one per 10 high power fields). All tumors were immunoreactive for cytokeratins (AE1/AE3 and CAM5.2). Inhibin was focally expressed by one tumor and its bone metastasis. Ultrastructurally, the cytoplasm of the neoplastic cells was packed with innumerable mitochondria. Cytologic atypia or mitotic rate cannot reliably predict the biologic behavior of oncocytic adrenocortical neoplasms. Large tumor size (4/4), extracapsular extension (3/4), blood vessel invasion (2/4), necrosis (4/4), and metastasis (1/4) are features of malignancy for oncocytic adrenocortical carcinomas. The treatment of these tumors is complete surgical excision.

'Spindle cell oncocytoma' of the adenohypophysis: a tumor of folliculostellate cells?

We describe five primary tumors of the adenohypophysis featuring mitochondrion-rich spindle cells. The patient ages ranged from 53 to 71 years (mean 61.6 years); two were female. All presented with panhypopituitarism. Two also had visual field defect. On neuroimaging all tumors showed suprasellar extension and were indistinguishable from pituitary adenoma. None showed imaging or operative evidence of dural involvement. All were gross totally removed: four by transsphenoidal surgery and one by frontal craniotomy. Follow-up ranged from 2 to 68 months (mean 35.4 months). No recurrences were noted. The clinical workup was noncontributory in all but two patients: one (case no. 4) with an oncocytic thyroid adenoma and another (case no. 5) with squamous carcinoma of both the uterine cervix and of vocal cord. Histologically, the five tumors were composed mainly of fascicles of spindle cells with eosinophilic, granular cytoplasm. Mitoses were rare and necrosis was absent. Neoplastic cells were immunoreactive for vimentin, epithelial membrane antigen, S-100 protein, and galectin-3. Stains for pituitary hormones, synaptophysin, chromogranin, glial fibrillary acidic protein, cytokeratin CAM5.2, smooth muscle actin, CD34, and CD68 were negative. No thyroglobulin immunoreactivity was noted in the tumor of case no. 4. Ultrastructurally, the neoplastic cells contained numerous mitochondria with lamellar cristae. The neoplastic cells were linked by intermediate junctions and desmosomes. No secretory granules were noted. The histologic, immunohistochemical, and fine structural features of these tumors were unlike those of pituitary adenoma or any other primary sellar tumor. A derivation from adenohypophyseal folliculostellate cells is suggested.

Cytokeratins 7 and 20 immunoreactivity in chromophobe renal cell carcinomas and renal oncocytomas

Chromophobe renal cell carcinomas and renal oncocytomas share morphologic similarities and may present a diagnostic challenge on routine hematoxylin-eosin staining. Currently recommended additional studies of Hale's colloidal iron staining and electron microscopy are often difficult to interpret and technically challenging and may not be readily available. Previous studies have reported conflicting results with regard to the cytokeratin 7 staining pattern in chromophobe renal cell carcinomas and renal oncocytomas. Cytokeratin 20 expression in chromophobe renal cell carcinomas has not previously been studied. Formalin-fixed paraffin-embedded tissue of 11 chromophobe renal cell carcinomas and 21 renal oncocytomas were retrieved from the archived files (1984-2000) of four teaching hospitals. Of the 11 chromophobe renal cell carcinomas, eight stained positive (73%) for cytokeratin 7, one stained focally positive (9%), and two cases (18%) were completely negative. Cytokeratin 7 staining of the 21 oncocytomas revealed 4 positive (19%), 7 focally positive (33%), and 10 negative cases (48%). Cytokeratin 20 was uniformly negative on all 11 cases of chromophobe renal cell carcinomas and all 21 cases of oncocytomas. Cytokeratin 7 does not appear to show the consistent immunoreactivity in chromophobe renal cell carcinomas and renal oncocytomas, as has been previously suggested. Cytokeratin 20 immunostaining in chromophobe renal cell carcinomas and renal oncocytomas is uniformly negative. Despite the technical and interpretive challenges of Hale's colloidal iron, it is still the most useful stain in differentiating chromophobe renal cell carcinomas from renal oncocytomas.

Peculiar cytoplasmic inclusions in oncocytic adrenal cortical tumors: an electron microscopic observation

Two cases of an oncocytic adrenal cortical tumor that contained peculiar cytoplasmic crystalline inclusions in the tumor cells are presented. The patients were 49- and 72-year-old females without clinical and biochemical evidence of adrenal cortical or medullary dysfunction. The adrenal tumors weighed 80 and 200 g each. These crystalline inclusions were present in groups of longitudinal profiles or clusters of crossly cut aggregates. They appeared in clusters of membrane-bound columns. On longitudinal sections, they appeared as rigid rods of homogenous density measuring 36 nm in width, but when they were cut transversely their paracrystalline nature became apparent. They were composed of closely packed microtubules in rectangular blocks. The microtubules measured 12.5 nm with a hollow center measuring 4.2 nm. The inclusions were within the membrane-bound cisterna of rough-surfaced endoplasmic reticulum. The significance of these inclusions is not clearly understood; however, they have been seen only in adrenal cortical tumors and their presence may be helpful in the differential diagnosis of adrenal oncocytic tumors. One patient presented with a tumor in which gross and microscopic appearance was compatible with a pheochromocytoma. This case exhibited an oncocytic appearance and pronounced cellular pleomorphism. Ultrastructural studies were necessary to recognize the tumor cells as cortical cells. The tumor cells contained abundant mitochondria with tubular cristae, paranuclear parallel stacks of granular endoplasmic reticulum, and relatively prominent smooth endoplasmic reticulum. These features are typical of adrenocortical cells. In addition, frequent tumor cells contained the peculiar cytoplasmic inclusions herein described.

Renal epithelial neoplasms: the diagnostic implications of electron microscopic study in 55 cases

Several unsettled histogenetic, nosologic and diagnostic considerations for renal epithelial tumors may have ultrastructural ramifications. Yet, a comprehensive electron microscopic study of renal epithelial neoplasms, in light of the recent classification, is not available. The ultrastructural findings from fifty-five renal epithelial neoplasms [31 clear cell renal cell carcinomas (RCC), 11 papillary RCC, 5 chromophobe RCC, 3 sarcomatoid RCC and 5 oncocytomas] were correlated with their light microscopic appearance. Clear cell RCC showed long microvilli similar to the brush border of the normal proximal tubules, with abundant cytoplasmic lipid and glycogen. Papillary RCC showed variably sized microvilli, and small amounts of cytoplasmic lipid, but no glycogen. Chromophobe RCC showed many cytoplasmic vesicles and abnormal mitochondria, with rare short and stubby microvilli. Renal oncocytoma showed many mitochondria with a few vesicles in the apical portion of the cytoplasm and rare short and stubby microvilli. The eosinophilic cell variants of clear cell RCC, papillary RCC and chromophobe RCC showed ultrastructural features similar to those of their respective prototypes, except for an increased numbers of mitochondria in the cytoplasm. One sarcomatoid clear cell RCC showed skeletal muscle differentiation. Two types of cytoplasmic inclusions, i.e. hyaline globules and granules similar to those in the Paneth cells (PC-like granules) were identified only in clear cell RCC, which displayed distinctive ultrastructural features. The current EM study demonstrates distinctive ultrastructural features of renal epithelial neoplasms. The findings lend additional support to the current classification of the pertinent tumor types, facilitate the differential diagnoses, and provide insights into the possible histogenesis of renal epithelial neoplasms.

Mixed tumors, myoepitheliomas, and oncocytomas of the soft tissues are likely members of the same family: a clinicopathologic and ultrastructural study

Four diagnostically unusual soft tissue tumors are presented. All lesions were of consistent size and long duration. Histologically, one lesion was analogous to mixed tumors of the usual sites (i.e., salivary glands), one lesion was totally spindled, and the two other lesions both had oncocytic appearances (epithelioid and spindle biphasic pattern in a case, purely epithelioid in the other). Immunohistochemically, the mixed tumor was positive for vimentin, cytokeratins, S-100 protein, and focally for EMA. The purely spindled tumor exhibited immunoreactivity for vimentin, actins, S-100 protein, EMA (focally), and GFAP. The oncocytic biphasic tumor was positive for mitochondrial antigen, vimentin, and actins. The purely epithelioid oncocytic neoplasm was immunoreactive only for mitochondrial antigen and vimentin. Ultrastructurally, in the epithelial-like portion of the first (mixed) tumor, peripheral arrays of contractile filaments were detected along with well-developed desmosomes. In the second (spindled) case, peripheral contractile filaments and attenuated desmosomes were also seen. In the third case, a huge number of mitochondria, some desmosomes, and actin-type microfilaments were found. In the fourth case, desmosomes and punctate subplasmalemmal densities, in addition to numerous mitochondria, were documented. In all cases an external basal lamina were present, which was discontinuous in the first three cases and almost continuous in the fourth. These tumors were respectively designated as mixed tumor, myoepithelioma of the classic type, myoepithelioma of oncocytic type with biphasic cell architecture, and true oncocytoma. So far, all tumors have followed benign clinical courses (median follow up: 12 months). Comparisons with similar tumors of other sites are drawn, and suggestions for considering all of them as members of the same myoepithelial-derived tumor family are given.

Renal oncocytoma with intracytoplasmic lumina: a case report with ultrastructural findings of "oncoblasts"

The authors present a case of renal oncocytoma with numerous intracytoplasmic lumina in a 45-year-old woman, with an emphasis on the ultrastructural findings of so-called oncoblasts. The tumor was located in the upper pole of the left kidney, measuring about 3.3 cm in diameter. Histologically, it was composed of solid nests or acinar growths of so-called oncocytic tumor cells with numerous intracytoplasmic lumina and scattered foci of so-called oncoblasts. The luminal surface was positive for Hale's colloidal iron stain. A very small number of glycogen-containing cells were found scattered in a few nests. Immunohistochemically, tumor cells were positive for cytokeratin and epithelial membrane antigen, but negative for vimentin and carcinoembryonic antigen. The Ki-67 labeling index was 1.2%. All of the Ki-67-positive cells were oncocytes. So-called oncoblasts were negative for Ki-67. Ultrastructural examination revealed that the predominant tumor cells had cytoplasm packed with round mitochondria and the mitochodria had lamellar long cristae. So-called oncoblasts showed scant cytoplasm with a moderate number of small mitochondria. Some of them showed pyknosis which can be regarded as mitochondrial involution. The authors believe that so-called oncoblasts are damaged or involuted oncocytes rather than precursors of oncocytes.

Immunohistochemical and ultrastructural study of clinically nonfunctioning pituitary adenomas

Sixty-five clinically nonfunctioning pituitary adenomas were studied by immunohistochemistry, and 12 cases were also analyzed by electron microscopy. Thirty-nine cases (60%) were immunohistochemically identified as hormone-producing adenomas. Six adenomas produced multiple hormones. Electron microscopy found seven null cell adenomas and five oncocytomas. The oncocytomas had a significantly higher incidence of hormone expression that the null cell adenomas. These results indicate that clinically nonfunctioning pituitary adenomas produce hormones, even though blood hormone levels are normal or low. Furthermore, the evidence of multihormonal production implies that two or more cell lineages including a protein hormone-producing type and a glycoprotein hormone-producing type may exist in the same nonfunctioning pituitary adenoma.

Ultrastructural observations on mitochondria and microvesicles in renal oncocytoma, chromophobe renal cell carcinoma, and eosinophilic variant of conventional (clear cell) renal cell carcinoma

On light microscopic examination, the morphologically overlapping features of granular eosinophilic cytoplasm in renal oncocytoma and the eosinophilic variants of chromophobe renal cell carcinoma and conventional (clear cell) renal cell carcinoma may pose difficulties in diagnosis. We investigated the ultrastructure of 5 renal oncocytomas, 7 eosinophilic variants of chromophobe renal cell carcinoma, and 5 eosinophilic variants of conventional (clear cell) renal cell carcinoma. Special attention was paid to mitochondria and microvesicles and interrelations thereof. The electron microscopic features were correlated with the light microscopic findings. All of the tumors had abundant mitochondria. Although abundant microvesicles were present in all of the chromophobe renal cell carcinomas, scant numbers of microvesicles were also sometimes present in renal oncocytomas (2 of 5) and in the eosinophilic variant of conventional (clear cell) renal cell carcinoma (1 of 5). The mitochondria in all three types of renal neoplasms studied differed in morphology, being predominantly uniform and round with predominantly lamellar cristae in renal oncocytoma, variable in shape and size with predominantly tubulocystic cristae in chromophobe renal cell carcinoma, and swollen and pleomorphic with rarefied matrix and attenuated cristae in the eosinophilic variant of conventional (clear cell) renal cell carcinoma. Variable numbers of mitochondria in all of the chromophobe renal cell carcinomas had outpouchings of the outer membranes, some of which carried parts of inner membrane within them. These outpouchings closely resembled the nearby cytoplasmic microvesicles, as did the tubulocystic cristae of the mitochondria. Some microvesicles contained homogeneous, electron-dense, finely granular matrix, similar to that seen in mitochondria. In one of seven chromophobe renal cell carcinomas, microvesicles were present in rough endoplasmic reticulum, and in two others, mitochondria were present within some vesicles. These features strongly suggest a close relationship between the microvesicles and mitochondria. Based on the role of vesicle formation in normal mitochondriogenesis, and some of our observations, we propose that defective mitochondriogenesis may be the source of microvesicles in chromophobe renal cell carcinomas.

Scanning electron microscopy of the interior of cells in Hürthle cell tumors

Four cases of Hürthle cell tumor were examined by scanning electron microscopy after being macerated to remove all soluble components. By all morphological criteria, Hürthle cells are oncocytes with their usual augmented complement of mitochondria. The Hürthle cell mitochondria either are ovate with central stacks of cristae or elliptical or rod-like with cristae that often are finger-like. As in salivary gland oncocytes, the shelf-like cristae are anchored to the inner boundary membrane by tubular necks. In some Hürthle cells, all of the mitochondria exhibit reticulate cristae. A few mitochondria harbor a globular inclusion in their inner compartment. The Golgi apparatuses are relatively simple, consisting of imbricated saccules that are edged by small, bud-like structures. The rare lumina in the midst of clusters of Hürthle cells are lined by numerous microvilli. Thus, scanning electron microscopy of macerated Hürthle cell tumors has revealed a number of features, especially of their mitochondria, that have escaped detection by transmission electron microscopy.

Bilateral renal oncocytoma in a Greyhound dog

A bilateral, locally invasive renal oncocytoma was diagnosed in a 10-year-old spayed female Greyhound dog. The diagnosis was based on positive staining of the tumor with the periodic acid-Schiff reaction prior to diastase treatment, on the immunohistochemical expression of cytoplasmic cytokeratin, and on the prominence of mitochondria in the tumor cells.

Hurthle cell adenoma of the mediastinum: intraoperative cytology and differential diagnosis with correlative gross, histology, and ancillary studies

A 66-year-old man was found to have a 7.5 cm mediastinal mass detected on routine chest X-rays as part of his preoperative work up for an inguinal hernia repair. An orthotopic (normally located) nongoitrous thyroid gland without evidence of connection to the mediastinal mass was also identified. The clinical differential diagnoses included lymphoma, thymoma, and germ cell tumor. Fine-needle aspiration (FNA) biopsy smears and touch imprints of the mediastinal mass showed a loosely cohesive, highly cellular population of relatively uniform cells with abundant granular cytoplasm, low nuclear to cytoplasmic (N/C) ratios, and prominent nucleoli consistent with a Hurthle cell (HC) neoplasm. Subsequently, the diagnosis of HC adenoma was confirmed on the surgically excised mediastinal mass. To the best of our knowledge, the surgical pathology and cytologic features of an HC adenoma of the mediastinum have not been reported in the literature. The gross, histologic, immunohistochemical, and electron microscopic (EM) findings, in addition to the cytologic features, are presented along with a differential diagnosis of this mediastinal neoplasm.

GANT-like gastrointestinal pacemaker cell tumours with oncocytic features

We describe two cases of gastrointestinal stromal tumours with prominent oncocytic features. Both had features consistent with differentiation towards the interstitial cells of Cajal (CC). They were composed of nests and bundles of cells with abundant, deeply granular, eosinophilic cytoplasm. Immunohistochemical investigations revealed positivity with c-kit, vimentin and CD34 antibodies in both neoplasms. Ultrastructurally the neoplastic cells showed characteristic features of CC; they had synapse-like structures and dense core cytoplasmic granules. Oncocytic features were confirmed by immunohistochemistry using anti-mitochondrion antibody in both cases and by electron microscopy in one case (case 1). Although the CC are frequently described as mitochondrion-rich cells, oncocytic changes have not previously been reported as a feature of gastrointestinal autonomic nerve tumour (GANT)-like stromal tumours.

Renal oncocytoma and chromophobe renal cell carcinoma. A comparison of colloidal iron staining and electron microscopy

Chromophobe renal cell carcinoma (RCC) is characterized by diffuse cytoplasmic staining with Hale colloidal iron (HCI) and the presence of numerous microvesicles. The eosinophilic variant morphologically may resemble renal oncocytoma. The latter commonly shows focal cytoplasmic HCI reactivity, but microvesicles have not been previously reported. We examined 19 chromophobe RCCs and 28 oncocytomas for their HCI staining patterns. Electron microscopy was performed on 13 chromophobe RCCs and 10 oncocytomas. In all cases of chromophobe RCC, more than 75% of cells showed a diffuse cytoplasmic HCI positivity, whereas a variable proportion of cells in 20 oncocytomas showed focal cytoplasmic staining, in a perimembranous, apical, or perinuclear pattern. Ultrastructurally, chromophobe RCCs contained abundant microvesicles with varying numbers of mitochondria, whereas all oncocytomas contained abundant mitochondria with focal collections of microvesicles. The microvesicles, in perimembranous, apical, or perinuclear clusters or singly scattered throughout the cytoplasm, were morphologically indistinguishable from those in chromophobe RCCs. In most cases, the microvesicle location and HCI staining pattern correlated. Chromophobe RCC and oncocytoma have distinctive morphologic features that usually allow their recognition. In difficult cases, HCI staining and electron microscopy may help, but the presence of HCI positivity or microvesicles in an eosinophilic renal tumor does not rule out oncocytoma.

Frequent chromosomal DNA unbalance in thyroid oncocytic (Hürthle cell) neoplasms detected by comparative genomic hybridization

Thyroid oncocytic (Hürthle cell) neoplasms represent a distinct subset of follicular thyroid tumors characterized by abnormal accumulation of mitochondria, whose chromosomal abnormalities have never been systematically analyzed. We have used comparative genomic hybridization to investigate chromosomal DNA alterations in 11 thyroid oncocytic tumors (7 adenomas and 4 carcinomas). Unbalanced chromosomal DNA profiles were detected in 6 of 7 adenomas and 3 of 4 carcinomas, numerical chromosomal aberrations being the dominant feature. Comparative genomic hybridization findings are compatible with two separate groups of tumors with karyotypic abnormalities, one characterized by multiple chromosomal gains with polysomy of chromosomes 5 and 7, the other by loss of chromosome 2. Pathologic and clinical features were similar in the two groups with no difference observed between adenomas and carcinomas. Activating H-, K-, or N-Ras mutations are commonly detected in follicular adenomas and carcinomas of the thyroid gland. However, Ras mutational analysis demonstrated that only one of the tumors in this series, an oncocytic carcinoma with a balanced karyotype, had activating Ras mutations (at codon 13 of K-Ras). The lack of Ras mutations in the 9 oncocytic neoplasms exhibiting chromosomal aneuploidy indicates that numerical chromosomal abnormalities are independent of activating Ras mutations in oncocytic tumors.

[Renal oncocytoma]

Authors review the case history of three patients with kidney tumours which had been surgically removed. In two of the cases radical nephrectomy while in one, organ-preserving surgery was performed. In all three cases histology revealed benign kidney tumours-oncocytomas. In light of the available literature authors indicate that preoperative diagnosis is almost impossible. Furthermore, it is their opinion that this benign kidney tumour has a less frequent occurrence than earlier thought.

Altered gap and tight junctions in human thyroid oncocytic tumors: a study of 8 cases by freeze-fracture

Human oncocytic tumors of the thyroid gland may be either adenomas or carcinomas. The morphology and the ultrastructure of these oncocytes are well-known. Numerous studies have demonstrated the role of gap and tight junctions in experimental and human carcinogenesis; however, the junctional complexes of the oncocytic tumors have never been studied. The aim of this study is to analyze gap and tight junctions in the oncocytic tumors of the thyroid. Because they are morphologically similar, whether benign or malignant, they offer an attractive model for studying the junctional complexes in both benign and malignant lesions. Eight oncocytic human thyroid tumors were collected and studied by freeze-fracture. Four of these cases were benign and four were malignant. Four cases of normal gland were also studied to represent the control group. Normal tight and gap junctions were described for the control group. No gap junctions could be found for the oncocytic tumors. Furthermore, alterations of the tight junctions were described; especially focal tights in the oncocytic adenomas and well organized and labyrinthic tight junctions in the oncocytic carcinomas. The lack of gap junction in the benign as well as in the malignant oncocytomas may suggest that the absence of gap junction is not sufficient for malignancy. The alterations of the tight junctions found in the oncocytic tumors of the thyroid are similar to those observed in poorly differentiated tissues or tumors, and may suggest a cellular regression rather than a tumorogenic factor.

Ocular adnexal oncocytoma: a case series and clinicopathologic review of the literature

The authors report the clinical, microscopic, and ultrastructural features of four oncocytic lesions involving the ocular adnexa. Three of the lesions originated in the ocular caruncle of elderly women, and a single case was encountered from the medial eyelid of an elderly man. Each lesion clinically presented as a slow-growing, painless, red mass. The histopathologic features were distinctive, with polyhedral cells containing granular eosinophilic cytoplasm found to consist of large numbers of mitochondria on ultrastructural examination. Of the 40 cases previously reported primarily in the ophthalmologic literature, the cases reported here similarly involved the eyelid and associated ocular adnexa with a predilection for elderly women. Oncocytomas probably represent an age-associated metaplastic and neoplastic transformation of the glandular epithelium comprising the ducts of salivary glands.

Oncocytic adrenocortical neoplasms: a report of seven cases and review of the literature

Oncocytic neoplasms of the adrenal gland are rare. We describe the clinicopathologic and immunohistochemical findings of seven oncocytic adrenocortical neoplasms, five oncocytomas, and two oncocytic neoplasms of uncertain malignant potential. Three tumors were studied using electron microscopy. These neoplasms occurred in five women and two men (median age, 55 years) with no clinical evidence that the neoplasms were functional. The size of the neoplasms varied from 5.0 cm to 13.5 cm. Histologically, each neoplasm was composed exclusively of oncocytes. The oncocytomas had very low or absent mitotic activity and no evidence of necrosis. The two oncocytic neoplasms of uncertain malignant potential had increased mitotic activity and necrosis but no evidence of invasion or metastases. Nuclear atypia, either focal or generalized, was found in all neoplasms. Immunohistochemical studies performed using fixed, paraffin-embedded sections showed strong reactivity with the mitochondrial antibody mES-13 in all neoplasms. Four of five oncocytomas and one oncocytic neoplasm of uncertain malignant potential expressed keratin, predominantly keratin 18, as shown using the CAM 5.2 and AE3 antibodies. Two neuroendocrine-associated markers, neuron specific enolase and synaptophysin, were positive in seven and five neoplasms, respectively. However, all neoplasms were negative for the other neuroendocrine markers tested, including chromogranin A, tyrosine hydroxylase, and dopamine beta-hydroxylase, as well as for epithelial membrane antigen, S100, and p53. Using the MIB-1 (Ki-67) antibody, proliferative activity was increased in both oncocytic neoplasms of uncertain malignant potential. All six patients with available clinical follow-up data are alive without evidence disease, although the follow-up interval is relatively short (< 2 years) for the two patients with oncocytic neoplasms of uncertain malignant potential. We conclude that oncocytic adrenocortical neoplasms are nonfunctional tumors that can become large before they are detected by radiologic studies. The majority of neoplasms are benign and should not be misdiagnosed as carcinoma.

Glassy hyaline globules in granular cell carcinoma, chromophobe cell carcinoma, and oncocytoma of the kidney

The presence of glassy hyaline globules (GHG) in renal carcinomas has been rarely emphasized in the literature. We studied the frequency of these globules in numerous renal carcinomas, including granular cell, mixed clear cell/granular cell, papillary renal cell, and chromophobe renal cell carcinoma, as well as oncocytomas. GHG are eosinophilic bodies in the hematoxylin-eosin stained sections with a size ranging from 1 to 30 micrometer and strongly positive with the periodic acid-Schiff (PAS) histochemical stain. Ultrastructurally, they are seen as amorphous secretion inside of the cisternae of the rough endoplasmic reticulum. GHG were found in 49 of 64 cases of granular cell and mixed clear cell/granular cell renal carcinomas and in 5 of 33 papillary renal cell carcinomas. No GHG were found in 22 cases of chromophobe cell carcinomas and 26 renal oncocytomas. Our findings suggests that GHG are a characteristic feature of granular cell carcinomas, mixed clear cell/granular cell renal carcinomas, and in a small minority of papillary renal cell carcinomas. In addition, it suggests that the presence of GHG in a renal cell tumor may be of aid for excluding a diagnosis of chromophobe cell carcinoma or oncocytoma.

Oncocytic carcinoma (malignant oncocytoma) of the breast

Three cases of oncocytic carcinoma of the breast observed in two women and one man are reported. One tumor was in situ and two were invasive. All three tumors were composed mostly of cells with "low-grade" nuclei and abundant granular eosinophilic cytoplasm. More than 70% of the neoplastic population in each case was immunoreactive with an antimitochondrion antibody. The presence of numerous mitochondria also was demonstrated at the ultrastructural level. Apocrine cells and oncocytes share similar morphologic features at the hematoxylin-eosin level; however, there are some differences that allow a confident distinction between these two cell types. Mitochondria in apocrine cells usually are in a perinuclear location and are not so numerous and diffusely dispersed as in oncocytes. In addition, apocrine cells display features of active secretory elements: prominent microvilli, well-developed Golgi complex, and electron dense secretory granules polarized toward the luminal pole; all these features were lacking in the three cases described. The cells constituting the present cases were not positive at the immunohistochemical and molecular levels for GCDFP-15/PIP mRNA, which are typical markers of apocrine differentiation. We suspect that mammary oncocytoma is a more common tumor than the meager number of reported cases suggests.

Usefulness of computer-aided karyometric examination in preoperative differentiation of Hürthle cell lesions

We have previously reported that there is a significant difference in the mean size of thyrocyte nuclei among patients with nodular goiter, follicular adenoma, and follicular carcinoma. In the present study, we have examined karyometric parameters of Hürthle cells in smears collected from 41 patients with Hürthle cells adenomas, Hürthle cells carcinomas, nodular goiter, and lymphocytic thyroiditis. The karyometric evaluation was performed with the image analysis computer system-Karyometry Manager 1.2. We measured the mean volume, the mean intersection area, and the mean perimeter of 100 nuclei in each routine smear. We found that the sizes of Hürthle cell nuclei could be arranged in the ascending order from the nodular goiter, through lymphocytic thyroiditis to Hürthle cell neoplasms, but those differences did not reach a border of statistical significance.

Diagnostic significance of mitochondria in four types of renal epithelial neoplasms: an ultrastructural study of 60 tumors

Mitochondrial morphology was studied in 60 renal epithelial neoplasms, including clear cell, papillary, chromophobe cell, and oncocytomas, to see if there are significant differences among the various subtypes. Mitochondria from the nephron tubular system obtained from 36 patients with glomerular diseases served as controls. Significant differences were found in mitochondrial ultrastructure in each of the subtypes of renal epithelial tumors. Novel observations were the presence of tubulovesicular cristae in many of the mitochondria found in chromophobe cell renal carcinomas and the discovery of a possible new oncocytic variant of this entity with mitochondria with pseudotubulovesicular and lamellar cristae similar to those of renal oncocytomas. This latter finding may be of prognostic significance, since renal oncocytomas are benign, while chromophobe cell neoplasms may behave in a malignant fashion.

Tall cell variant of papillary thyroid carcinoma: cytologic features and differential diagnostic considerations

The cytologic features of the tall cell variant (TCV) of papillary thyroid carcinoma may be confused with those of other thyroid neoplasms with different prognoses and treatment modalities. Elucidation of the cytomorphology of this variant would be useful in planning treatment for this fairly aggressive variant of papillary carcinoma. The cytologic features of 20 cases of TCV were compared with those of 23 cases of the usual variant (UV) of papillary thyroid carcinoma and of 10 Hürthle-cell neoplasms (HCN). After a set of features was defined, the efficacy of employing it to distinguish TCV from UV and HCN was assessed by three cytopathologists (J.D.T., I.R., and M.O.), was independently examined 15 unknown cases selected by the first author. Aspirates of TCV showed some specific cytologic features which included large cell size with abundant granular cytoplasm and variably sized nuclei with granular chromatin. The cells were sometimes columnar, but more often were polygonal, and prominent cytoplasmic borders were present in 50% of cases. Intra-nuclear inclusions were more prominent in TCV than in UV. There was some overlap in the cytomorphology of some TCV and UV cases, and variable numbers of cells with UV features were encountered in TCV cases. Employing the cytologic features of TCV listed above, three cytopathologists examined the unknown cases, which included 7 cases of TCV, 4 cases of UV, and 4 cases of HCN. TCV was recognized as such by all three cytopathologists in 6 of 7 cases, and all UV and HCN were correctly typed by all three examiners. The cytologic features of TCV are sufficiently distinctive to enable separation from HCN and most cases of UV. Although the diagnosis of TCV may be rendered employing fine-needle aspiration biopsy, material, this diagnosis should be limited, in our opinion, to specimens which contain at least 30% of cells with typical TCV features.

Immunocytochemical study of pituitary oncocytic adenomas

Using immunocytochemistry we have analyzed 8 pituitary oncocytomas, 14 null cell adenomas, and 2 oncocytomas of the parotid gland (Warthin's tumor). The proportions of adenoma cells that are positive for mitochondrial protein (MP), cytochrome oxidase (COX), and manganese-superoxide dismutase (Mn-SOD) were significantly higher in pituitary oncocytomas than in null cell adenomas (MP P < 0.001, COX P < 0.001, Mn-SOD P < 0.05). In pituitary oncocytomas, MP-positive cells were distributed unevenly but in clusters or in islets admixed with some MP-negative cells, and corresponded to COX-positive cells. In contrast, almost all of the oxyphilic epithelial cells of Warthin's tumor were positive for MP, COX, and Mn-SOD. On the other hand, both pituitary tumors displayed similar findings with regard to the proportion of adenoma cells immunoreactive for copper/zinc-SOD and adenohypophysial hormones, the Ki-67 (MIB-1) proliferating cell index, and the mean number of argyrophilic nucleolar organizer regions. It was confirmed that immunocytochemical identification of MP and COX is useful for distinguishing pituitary oncocytomas from null cell adenomas. Although it remains to be determined whether oncocytomas originate from oncocytic changes of tumor cells or from neoplastic transformation of oncocytic cells, it appears that tumorigenesis of pituitary oncocytomas differs from that of Warthin's tumor.

Oncocytic meningioma

Six cases of meningioma showing oncocytic changes are described. The lesions were composed mostly of sheets, nests, and cords of large polygonal cells with finely granular eosinophilic cytoplasm rich in mitochondria. Neoplastic cells showed nuclear pleomorphism with prominent nucleoli. Necrosis and high mitotic rate were present in the majority of cases. Oncocytic differentiation was demonstrated by conventional histology, immunocytochemistry, electron microscopy, and Western-blot analysis. Oncocytic meningiomas showed an aggressive behavior; recurrences were observed in three cases, and invasion of brain cortex was evident in other two cases.

Hyaline globules in renal cell carcinomas and oncocytomas

Hyaline globules (extracellular collections of amorphous material) are identified in 10 of 59 renal cell carcinomas (RCC) and in 2 of 9 oncocytomas. Immunohistochemical characterization of these PAS-positive structures revealed the presence of basement membrane material in most cases. Collagen type IV and laminin were the predominant constituents, whereas fibronectin was detected only occasionally. Electron microscopic examination of the globules showed concentric multilayered accumulations of basement membrane material. No such structures were recognized in 8 renal pelvic transitional cell carcinomas nor in 2 metanephric adenomas. RCC associated hyaline globules were always negative for alpha1-antitrypsin (AAT), alpha-fetoprotein (AFP), amyloid A, cytokeratin, vimentin, or lysozyme. These features differ from those of the hyaline globules previously described in other malignant neoplasms, notably AAT-positive hyaline globules in ovarian tumors, and AFP-positive globules in yolk sac tumors. Identification and immunohistochemical characterization of hyaline globules in metastases may be helpful in determining the origin of occult primary tumors.

Immunocytochemical and immunoelectron microscopical analysis of BCL2 expression in thyroid oxyphilic tumors

In both human lymphoma and carcinoma, BCL2 expression contributes to the neoplastic development by preventing normal turnover due to programmed cell death. In thyroid carcinoma it was shown that BCL2 expression is related to cell differentiation and appears to be associated with a less aggressive behavior. Using immunogold electron microscopy labeling techniques on ultrathin frozen sections, the authors undertook an analysis of bcl-2 protein localization in 7 cases of thyroid tumor with (4 cases) or without (3 cases) oncocytic differentiation, which displayed histopathological features, corresponding to different degree of aggressiveness. All thyroid tumors and a lymphoblastoid cell line overexpressing BCL2 showed a preferential labeling of mitochondrial circumference, while the 4 cases with oncocytic differentiation displayed a bcl-2 protein location, not only on the circumference but also on the cristae of a consistent number of mitochondria. These results may indicate a bcl-2 protein interaction with intramitochondrial constituents related to the neoplastic transformation in oncocytic tumor.

Oncocytomas of the submandibular gland. A series of 22 cases and a review of the literature

BACKGROUND

Oncocytomas are benign salivary gland neoplasms that represent approximately 1.5% of all salivary gland tumors. Oncocytomas of the submandibular gland, however, are decidedly uncommon.

METHODS

Twenty-two cases of submandibular gland oncocytomas from the files of the Oral and Otolaryngic Tumor Registries of the Armed Forces Institute of Pathology were reviewed, and analysis of the histologic criteria, histochemical and immunohistochemical reactions, and ultrastructural and clinical follow-up data was performed.

RESULTS

The patients included 11 females and 11 males, age 21-88 years, with a mean age at presentation of 58.7 years. Clinically, the tumors were generally asymptomatic masses in the submandibular gland that increased in size over a period ranging from several weeks to 20 years and were occasionally associated with pain (n = 9). The tumors ranged in greatest dimension from 0.7 to 7 cm and were circumscribed to encapsulated. Histologically, the tumors were characterized by large epithelial cells with eosinophilic, granular cytoplasm. The cytoplasm stained positively with stains used to demonstrate mitochondria (phosphotungstic acid-hematoxylin, Novelli, Cresylecht violet V, and Kluver-Barrera Luxol fast blue stains). Immunohistochemical reactions demonstrated an epithelial origin (keratin and epithelial membrane antigen), whereas markers for myoepithelial derivation (S-100 protein, actin, and glial fibrillary acidic protein) were not identified. At the time this study was conducted, all patients with submandibular oncocytomas were either alive without evidence of disease or had died without evidence of recurrent disease, with surgical resection the only treatment.

CONCLUSIONS

Submandibular gland oncocytomas are rare, benign tumors. The tumor cells are filled with mitochondria, which are easily demonstrated by histochemical reactions. Complete surgical resection is adequate therapy.

The t(1;12)(p36;q13) in a renal oncocytoma

A new chromosome rearrangement, t(1;12)(p36;q13), is added to the cytogenetic changes found in renal oncocytomas. The breakpoint in 12q is cytogenetically different from those of the MAR region, and molecularly HMGIC located in 12q15 on the basis of 3' RACE experiments does not seem to be directly involved.

Oxyphil cell adenoma (oncocytoma) of the lacrimal caruncle: a case report

The onset of oncocytic neoplasms in the ocular area is exceptional. A rare case of oxyphil cell adenoma of the lacrimal caruncle in an 81-year-old woman is presented. The anatomo-clinical profile of this benign small tumor is drawn up: a slowly growing tumor, generally occurring in the caruncle of elderly women, which is characterized by a uniform population of epithelial cells with eosinophilic finely-granular cytoplasm containing large numbers of mitochondria. The histogenetic problem of this tumor is briefly discussed.

Renal oncocytoma. Pathological evaluation and clinical implications

Renal oncocytoma is a benign tumour of renal tubular origin; oncocytes are transformed epithelial cells rich in mitochondria, probably representing senescent degenerative cellular changes. Most of renal oncocytomas usually follow a benign clinical course and partial nephrectomy or enucleation has been advocated as curative. By immunohistological staining of tissue sections using monoclonal antibodies (DBA, SBA, PNA, UEA, Cytocheratine), we can suppose the histogenetic origin of renal oncocytomas from a region other than the proximal tubular epithelium, and in particular from the collecting duct epithelium. We believe that it is most important to perform flow cytometry to study the chromosomal pattern of the tumour, once intra-operative frozen sections have advanced the suspicion of renal oncocytoma; if oncocytic cells show a diploid pattern, and the tumour mass is well circumscribed and has not an excessive diameter, we favour renal sparing surgery.

Soft tissue oncocytoma

We describe a case of a novel soft tissue neoplasm, composed of a monotonous population of cells. Their cytoplasm was parked with mitochondria, and had no immunohistochemical or ultrastructural evidence of differentiation. The neoplasm, located within the thigh of a 50-year old man, was well-circumscribed but unencapsulated. The patient was clinically free of neoplasm at 1 year follow-up, after complete local excision. We propose the term "soft tissue oncocytoma" for this lesion, because of the similarity of this neoplasm to oncocytomas of other reported sites.