1/6. Giant renal oncocytoma.We report the largest renal oncocytoma excised at the initial presentation and the second largest renal oncocytoma in published reports. Despite a tendency for renal oncocytomas to be relatively small and asymptomatic compared with renal cell carcinomas, these lesions cannot be reliably differentiated preoperatively. The variable nature of presentation and overlap of radiographic characteristics between these lesions complicates their clinical differentiation. The present case illustrates the difficulty in the preoperative diagnosis of even very large, enhancing renal masses and reinforces the inclusion of renal oncocytoma in the differential diagnosis of these lesions.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/6. Incidentally detected giant oncocytoma arising in retroperitoneal heterotopic adrenal tissue.A nonfunctional retroperitoneal oncocytoma incidentally discovered in a 40-year-old woman is described. The tumor, which was 17 cm in largest dimension, was completely separated from the kidneys and adrenal glands and consisted of nests of polygonal cells with large, granular, eosinophilic cytoplasm. Significant nuclear atypia, necrosis, and mitosis were absent. Ultrastructural analysis confirmed the oncocytic nature of the neoplastic cells. Since neoplastic cells were not immunoreactive for chromogranin and did not contain dense-core secretory granules, the diagnosis of oncocytic paraganglioma was excluded. cells immunoreactive for 3beta-hydroxysteroid dehydrogenase, the enzyme catalyzing the conversions of pregnenolone to progesterone and dehydroepiandrosterone to androstenedione, were identified in the tumor, thus strongly indicating adrenocortical tissue origin. Multiple nests of 3beta-hydroxysteroid dehydrogenase-positive cells were detected in the loose retroperitoneal connective tissue. These findings strongly support the origin of the tumor from heterotopic retroperitoneal rests of the adrenal gland. To our knowledge, only 1 similar case has been described in the literature to date.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/6. 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.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
4/6. Oncocytic carcinoma of the parotid gland.BACKGROUND: Oncocytic carcinoma is a rare tumor of major salivary glands. Despite being described 5 decades ago, not much is known about these rare tumors. Histochemical or electron microscopic confirmation of the oncocytic nature of the tumor cell is needed for differential diagnosis. The main treatment modality is surgery with or without adjuvant radiotherapy. Malignant oncocytomas have the potential risk of developing distant metastases and demand long term follow-up after therapy. CASE REPORT: A 58-year old man presented with a recurrent mass in the left parotid gland with a prior diagnosis of monomorphic adenoma in the same localization which had been treated by tumor excision in July 2002. Left superficial parotidectomy followed by radiotherapy into tumor bed and upper neck were carried out in September 2004. To date, he has had no evidence of recurrence for 14 months. CONCLUSION: For an accurate approach in the management of patients, oncocytic adenocarcinoma should be considered in the differential diagnosis of lesions of the parotid gland, most of which are benign.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
5/6. Renal oncocytoma. A rare entity in poland.Renal oncocytoma represents a special category of renal tumours and accounts for 3-5% of renal neoplasms. Usually they are incidental findings. Most reports have demonstrated their benign nature but a few cases of high-grade oncocytomas were reported to have metastasized. In poland, between 1971 and 1991, 7 patients (4 women, 3 men) underwent radical nephrectomy for oncocytoma. The author describes here one case of rare oncocytoma malignum.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
6/6. Adrenocortical oncocytoma: case report and review of the literature.Only 9 oncocytic neoplasms of true adrenal origin have been described to date. It therefore seemed of interest to study the histochemical and ultrastructural features of a non-functioning monolateral adrenocortical oncocytoma which was incidentally detected by ultrasonography and magnetic resonance imaging in a 28-year-old woman. The tumor was round, well encapsulated and weighed 73 g. It consisted of islets of eosinophilic cells, and did not display any sign of necrosis. The proliferation rate (as evaluated by mitotic index and percentage of MIB-1 Ki67 positive cells) was low, and atypic mitoses were absent; some rare cells with nuclear atypias were observed and the capsule was focally invaded by oncocytes. Immunocytochemistry did not show expression of vimentin or cytokeratin. The oncocytes had an abundant cytoplasm packed with mitochondria containing plate-like cristae. Smooth endoplasmic reticulum was virtually absent, while rough endoplasmic reticulum cisternae and free ribosomes were abundant. Although the classic histological approach clearly indicates the benign nature of the tumor, the immunocytochemical and ultrastructural features of oncocytes may suggest their potential for malignant behavior.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |