Organ-preserving surgery in renal cell carcinoma: tumor enucleation versus partial kidney resection

Organ-preserving surgery is attempted in cases of small renal cell carcinoma, especially when such tumors occur bilaterally or in an anatomical or functional solitary kidney. It is still a matter of debate how much of the peritumoral renal tissue has to be removed for optimal cure rates. Enucleation of the neoplasm as well as partial nephrectomy have been advocated. The relation of renal cell carcinomas to their pseudocapsule and to the adjacent renal parenchyma was examined using microangiographic and histopathologic techniques. In a number of cases in our series a total or partial enucleation ex situ permitted an investigation of the enucleate and tumor bed. The pseudocapsule of all tumors was invaded by neoplastic cells and the surrounding renal parenchyma was often infiltrated by the carcinoma, even around some of the smallest tumors. Comparison of tumor vascularization with the histologic features led to the suggestion of a more aggressive behavior of renal cell carcinomas once they have exceeded a certain size. Thus, in contrast to larger carcinomas, tumors with a diameter of less than 6 cm most often show a radial vascular pattern and lack central necrosis. These parameters can be evaluated by noninvasive investigative techniques. Smaller tumors appear amenable to conservative surgical treatment; however, in view of our histopathologic findings, a sufficiently wide margin of adjacent renal parenchyma should always be removed with the tumor.     

Technik der Thymuschirurgie

The group of thymic tumors includes thymomas, thymic carcinomas and neuroendocrine thymic tumors (NETT). They are rare tumor entities but represent the majority of malignant tumors of the anterior mediastinum in adult patients. The biological behavior is characterized by slow tissue infiltration and locoregional tumor spread. Complete surgical resection is the foundation of the treatment of thymic tumors. Early tumor stages can be addressed by minimally invasive surgical procedures. In 30?% of patients the tumors already infiltrate additional mediastinal structures, the lungs or the chest wall warranting extended surgical approaches. This review article summarizes the operative approaches available for thoracic surgeons. Knowledge of the available surgical techniques in thymic surgery can be transferred to other mediastinal tumors.     

Myoepithelial Tumors of Bone

Myoepithelial tumors (METs) of bone (BMETs) are a rare but distinct tumor entity. METs that are cytologically benign are termed myoepitheliomas; METs with malignant histologic features are called myoepithelial carcinomas. BMETs have a wide age range, may involve any part of the skeleton, and have a variable spindle cell and epithelioid morphology. Bone tumors to be considered in the differential diagnosis are discussed. Additional techniques are indispensable to correctly diagnose BMETs. By immunohistochemistry, BMETs often express cytokeratins and/or EMA together with S100, GFAP, or calponin. Half of BMETs harbor EWSR1 (or rare FUS) gene rearrangements with different gene partners.     

Mucinous tumors of the ovary: a clinicopathologic analysis of 75 borderline tumors (of intestinal type) and carcinomas.

With the exception of benign cystadenomas, mucinous ovarian tumors are rare and heterogeneous neoplasms. They have been classified as either borderline tumors or carcinomas for almost 30 years. Subsequently, the borderline tumors have been subclassified into endocervical-like and intestinal types. The diagnostic criteria for distinguishing borderline tumors of the intestinal type from mucinous carcinomas have varied, making difficult the interpretation of prognostic information. More recently, a further subdivision of the former tumors into forms with only epithelial atypia and variants with focal intraepithelial carcinoma has been proposed. Consequently, in this study of 41 mucinous borderline tumors of intestinal type and 34 mucinous carcinomas, the former were also subdivided into 30 cases with mild to moderate atypia only and 11 with areas of intraepithelial carcinoma. All 30 purely borderline tumors were stage I tumors, and all 15 with follow-up information (including one case with microinvasion) were clinically benign. All 11 mucinous borderline tumors that had foci of intraepithelial carcinoma were also stage I neoplasms, and none of the eight patients with follow-up data (including one with microinvasive carcinoma) recurred. Thirty-four invasive carcinomas were subclassified into 15 expansile and 19 infiltrative subtypes. All 15 carcinomas with only expansile invasion were stage I; none of the 11 with follow-up data recurred. Three of nine patients with stage I infiltrative carcinomas with follow-up information had a fatal recurrence. Eight of the remaining 10 infiltrative carcinomas had extended beyond the ovary at the time of diagnosis (stages II and III); of the six patients with follow-up data, four died of tumor and two were alive with disease. In stage I carcinomas nuclear grade and tumor rupture correlated with unfavorable prognosis, but less than infiltrative invasion. However, all three fatal tumors were infiltrative carcinomas that had ruptured, and two contained grade 3 malignant nuclei. Combination of infiltrative invasion, high nuclear grade, and tumor rupture is a strong predictor of recurrence for stage I mucinous ovarian tumors. Among the 19 infiltrative tumors, 13 contained foci of anaplastic carcinoma. Of the seven patients with stage I tumors and follow-up data, only one patient whose tumor had ruptured intraoperatively had a fatal recurrence. The presence of anaplastic components in stage Ia (intact) carcinomas did not have an adverse effect in their outcome, even when the undifferentiated carcinomatous elements appeared in the form of mural nodules.     

Early undifferentiated pancreatic carcinoma with osteoclastlike giant cells: direct evidence for ductal evolution

Undifferentiated (anaplastic) carcinomas of the pancreas are rare. To a variable degree, they may contain osteoclastlike giant cells and are then sometimes referred to as osteoclastlike giant cell tumors. The histogenesis of these tumors has been discussed with great controversy. Thus, as a result from numerous histomorphologic, immunohistochemical, ultrastructural, and molecular examinations, frequently performed as single case studies, it has been concluded that undifferentiated carcinomas and osteoclastlike giant cell tumors of the pancreas originate from epithelial cells, mesenchymal cells, undifferentiated precursor cells, or stem cells. However, to date, early stage tumors have not been described, most likely because of the fact that at the time of diagnosis the tumors have commonly reached advanced stages with large tumor size. In this report, we present the case of an undifferentiated pancreatic carcinoma with osteoclastlike giant cells, which was incidentally detected at a very early stage in a pancreatitis specimen. Our histomorphologic and immunohistochemical findings not only provide evidence for a ductal origin, but for the first time document initial steps in the evolution of these tumors. Therefore, we suggest that the tumor should be considered as an anaplastic variant of pancreatic ductal adenocarcinoma.     

Triple-Negative Breast Carcinoma

Triple-negative breast carcinomas (TNBCs) comprise approximately 15% to 20% of breast cancers. Accurate assessment of tumor estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) status is an essential part of classifying tumors into this group. As a group, these tumors are associated with poor clinical outcomes and have been shown to exhibit an increased propensity for hematogenous metastasis to the brain and lungs. Many TNBCs, particularly ductal, not otherwise specified (NOS), and metaplastic carcinomas, show an overlapping characteristic gene expression pattern when evaluated by cDNA microarrays. This group has been termed basal-like because of the similarity with normal breast basal/myoepithelial cells including basal cytokeratin expression and lack of hormone receptor and HER2 expression. The array data have been used to develop multiple immunohistochemical surrogates to identify basal-like tumors in formalin-fixed, paraffin-embedded tissues, most employing basal cytokeratins and epidermal growth factor receptor. Currently, there is no international consensus on biomarkers used to identify tumors as basal-like, and the routine use of the term basal-like in surgical pathology reports is premature. Tumor morphologic features associated with triple-negative status include Nottingham grade 3 with high mitotic rate, pushing border of invasion, geographic tumor necrosis, solid/sheet-like growth pattern, lymphocytic infiltrate, and large central acellular zone. Most breast cancers arising in patients who have a germ-line BRCA1 mutation show similar histologic features and a triple-negative phenotype. Not all TNBCs are associated with an unfavorable prognosis, drawing attention to the heterogeneity of this tumor group and the continued need to link tumor morphology and grade with triple-negative status. This article focuses on histopathology, molecular characterization, carcinogenesis, clinical behavior, and treatment of these tumors.     

Neuroendocrine carcinomas of the colon. Ultrastructural and biochemical evidence of their secretory function.

Four cases of malignant colonic tumors diagnosed by light microscopy as "small cell undifferentiated carcinomas" were shown by electron microscopy to have neurosecretory-type granules. Biochemical analysis of tumor tissue extracts disclosed the presence of considerable levels of VMA and catecholamines in all tumors; 5-HIAA was present in one tumor. Clinically, there had been no signs or symptoms attributable to those or related substances. Similar observations have been reported in a variety of neuroendocrine neoplasms; for example, the demonstration of neurosecretory-type granules and determination of amine or peptide materials in tumor tissue or body fluids may not be necessarily reflected in clinical hormonal syndromes or obvious metabolic abnormalities. Our structural and biochemical observations indicate that, regardless of clinically evident hormonal activity or lack thereof, some small cell "undifferentiated" colonic cancers derive from APUD elements, and therefore they should be classified within the group of neuroendocrine carcinomas. The evident secretory capabilities of these carcinomas suggest obvious diagnostic possibilities and could conceivably lead to a reappraisal of current therapy.     

Desmosomal plaque proteins are preserved in all grades of breast cancer. An immunohistochemical study utilizing monoclonal antibodies to desmoplakin

Using a monoclonal antibody specific for desmoplakin, we evaluated 52 breast carcinomas, 25 normal tissues, 10 benign breast lesions, and 14 nonepithelial tumors. Carcinomas were classified as ductal or lobular, and they were graded histologically according to degree of malignancy and differentiation. Nonepithelial tumors were negative for desmoplakin. All carcinomas stained positively. Desmosomal staining occurred along epithelial cell borders as discrete, punctate granules. Staining intensity was similar in infiltrating carcinomas, in situ carcinomas, benign breast lesions, and normal breast epithelium. Our study demonstrates that most infiltrating breast carcinomas retain abundant desmoplakin, regardless of tumor grade, degree of differentiation, or tumor type (duct or lobular). Although altered desmosomal structure may be important, our findings suggest that loss of desmosomes is not necessary for tumor invasion or metastasis. Desmosomes have a characteristic staining pattern that is easy to interpret, and monoclonal antibodies to desmoplakin may prove useful as markers for distinguishing undifferentiated carcinomas from nonepithelial cancers.     

Secondary and metastatic tumors of the orbit

We have presented three cases of metastatic tumor to the orbit. The first case illustrated metastatic tumor that originated from a cutaneous basosquamous cell carcinoma. This lesion, first reported by MacCormac as being morphologically intermediate between basal and squamous cell carcinoma, has become a topic of some controversy. Conley reported these tumors to represent 1% of basal cell carcinomas. Several authors have reported a higher incidence of recurrence with these lesions, as compared with the ordinary basal cell tumors. Recurrence of basal cell carcinomas are reported as approximately 10%, but are four times greater in the basosquamous cell tumors. The incidence of metastasis with the basosquamous cell tumors has been reported in between 37% and 51% of cases. The second case represented involvement of the orbit by direct extension of a facial squamous cell carcinoma. As illustrated by this case, these tumors can be very aggressive and should be treated with respect. The third case showed the metastatic potential of the nephroblastoma with metastatic tumor that involved the eye, orbit, and maxilla. Diagnostic techniques available in evaluation of these tumors include CT scan, magnetic resonance (MR) imaging, ultrasound, open biopsy, and fine-needle aspiration. Li et al., in an article that compared MR imaging, CT scan, and ultrasound concluded that MR imaging, with the use of the 0.15 T resistive magnet, offered no distinct advantage over the combination of CT and ultrasound in evaluation of patients with orbital tumors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Technical aspects and surgical strategy for removal of corticotroph pituitary adenoma

The development of transsphenoidal microsurgery and the refinement of endocrinological and radiological diagnostic procedures have afforded therapeutic options appropriate for each individual case in patients with pituitary-dependent hypercortisolism. Compared with other secreting pituitary tumors, the corticotroph adenoma seems to be the most biologically active tumor. Clinical evidence of hypercortisolism mainly occurs at an early stage of tumor growth when the tumor is very small, below the detection threshold of modern imaging techniques. While the treatment of large tumors remains difficult due to the non-discrete boundary lines of the tumor and extension or invasion, surgical removal of very tiny tumors requires reliable preoperative or peroperative identification in order to achieve total tumor resection for clinical remission and pituitary preservation to prevent hypopituitarism. We reviewed all the current surgical techniques or clever surgical procedures used to achieve both goals with the lowest complication rate. We report here the state-of-the-art of surgical management of corticotroph pituitary adenoma focusing on preoperative radiological and biological data required for performing guided intrasellar surgical exploration and reliable tumor identification. Different technical aspects of the nasosphenoidal approaches are reported as well as the modified transdiaphragmatic or transtubercular transcisternal approaches to tumors in a suprasellar localization or lying along the pituitary stalk. The advantages of minimally invasive surgical techniques such as intrasellar endoscopic surgery are discussed. Adapted surgical techniques for second transnasal surgery indicated for recurrent tumors are described. Guidelines are given for peroperative tumor identification with macroscopic assessment or histological control with frozen section biopsies. Different techniques for tumor removal are discussed from selective microadenomectomy to enlarged pituitary resection and total hypophysectomy. Methods for preoperative guidance of total tumor removal are proposed including histological or biological assessment of normal adjacent pituitary tissue. the strategy of surgical intrasellar exploration and tumor resection is outlined using a set of algorithms. The first is devoted to positive preoperative documentation of the tumor. The second is proposed for the surgical scenario where there is no preoperative MRI evidence of the tumor. Special strategies are discussed for ectopic adenoma or multiple tumors. Revision surgical management after surgical failure or tumor recurrence is described. Special guidelines for surgical treatment of large clinically silent corticotroph macroadenomas are given with emphasis on the high risk of recurrence in comparison with other silent pituitary tumors such as gonadotroph or immunonegative adenomas.     

Invasive ductal carcinomas of the breast showing partial reversed cell polarity are associated with lymphatic tumor spread and may represent part of a spectrum of invasive micropapillary carcinoma

Invasive micropapillary carcinomas (IMPC) of the breast are aggressive tumors frequently associated with lymphatic invasion and nodal metastasis even when micropapillary (MP) differentiation is very focal within the tumors. We have noticed that some breast carcinomas showing lymphatic spread but lacking histologic features of IMPC have occasional tumor cell clusters reminiscent of those of IMPC without the characteristic prominent retraction artifact. To study the clinicopathologic significance of such features, we prospectively selected 1323 invasive ductal carcinomas and determined the presence and extent of MP differentiation and retraction artifact in the tumors. One representative tumor block per case was used for immunostaining for epithelial membrane antigen (EMA). Partial reverse cell polarity (PRCP) was defined as prominent linear EMA reactivity on at least part of the periphery of tumor cell clusters usually associated with decreased cytoplasmic staining. The clinicopathologic features of carcinomas with PRCP were compared with IMPC and invasive ductal (no special type) carcinomas without this feature. Of the 1323 cases, 96 (7.3%) and 92 (7.0%) showed MP features and the presence of PRCP, respectively. We found that the presence of both PRCP and MP features were strongly associated with decreased cytoplasmic EMA immunoreactivity and the presence of lymphatic invasion and nodal metastasis, even if such features were present only very focally. Our results suggest that breast carcinomas with PRCP may have the same implication as MP differentiation and these tumors may represent part of a spectrum of IMPC. Complete or partial reversal of cell polarity may play a significant role in lymphatic tumor spread.     

Molecular Pathology: Predictive,Prognostic, and Diagnostic Markers in Salivary Gland Tumors

Although initial attempts at using ancillary studies in salivary gland tumor classification were viewed with skepticism, numerous advances over the past decade have established a role for assessment of molecular alterations in the diagnosis and potential prognosis and treatment of salivary gland tumors. Many monomorphic salivary tumors are now known to harbor defining molecular alterations, usually translocations. Pleomorphic, high-grade carcinomas tend to have complex alterations that are often further limited by inaccuracy of initial classification by morphologic and immunophenotypic features. Next-generation sequencing techniques have great potential in many aspects of salivary gland tumor classification and biomarker discovery.     

Inzidentelle T1b- bis T3-Gallenblasenkarzinome

Background

The immediate radical re-resection (IRR) after simple cholecystectomy in incidental gallbladder carcinoma (IGBC) is debated in the literature. The German S3 guidelines recommend IRR in T2 and more advanced stages. Current literature recommends more extensive surgery even in T1b tumors.

Methods

The German registry database was used for this study.

Results

To date 883 cases of IGBC have been analyzed. In 8 out of 39 patients with a T1a tumor IRR was carried out as well as in 43 out of 109 patients with a T1b tumor. There was a significant survival benefit for re-resected T1b patients. There was also a significant survival benefit for the 215 T2 tumors and the 75 T3 patients with IRR compared to the 441 T2 tumors and 207 T3 tumors without IRR. Comparison of liver resection techniques showed good results for the wedge resection technique in T1b and T2 carcinomas. For T3 carcinomas more radical techniques showed better results. Less than 50?% of T2–3 tumors in the registry have been re-resection.

Conclusions

The IRR should be highly recommended in patients with T1b and more advanced IGBC. The wedge resection technique is an attractive procedure for T1b and T2 IGBC due to the lower invasiveness in spite of oncological adequacy.     

Mutation and loss of expression of ARID1A in uterine low-grade endometrioid carcinoma

ARID1A is a recently identified tumor suppressor gene that is mutated in approximately 50% of ovarian clear cell and 30% of ovarian endometrioid carcinomas. The mutation is associated with loss of protein expression as assessed by immunohistochemistry. In this study, we evaluated ARID1A immunoreactivity in a wide variety of carcinomas to determine the prevalence of ARID1A inactivation in carcinomas. Mutational analysis of ARID1A was carried out in selected cases. Immunoreactivity was not detected (corresponding to inactivation or mutation of ARID1A) in 36 (3.6%) of 995 tumors. Uterine low-grade endometrioid carcinomas showed a relatively high-frequency loss of ARID1A expression, as 15 (26%) of 58 cases were negative. The other tumor that had a relatively high-frequency loss of ARID1A expression was gastric carcinoma (11%). Mutational analysis showed 10 (40%) of 25 uterine endometrioid carcinomas; none of 12 uterine serous carcinomas and none of 56 ovarian serous and mucinous carcinomas harbored somatic ARID1A mutations. All mutations in endometrioid carcinomas were nonsense or insertion/deletion mutations, and tumors with ARID1A mutations showed complete loss or clonal loss of ARID1A expression. In conclusion, this study is the first large-scale analysis of a wide variety of carcinomas showing that uterine low-grade endometrioid carcinoma is the predominant tumor type harboring ARID1A mutations and frequent loss of ARID1A expression. These findings suggest that the molecular pathogenesis of low-grade uterine endometrioid carcinoma is similar to that of ovarian low-grade endometrioid and clear cell carcinoma, tumors that have previously been shown to have a high-frequency loss of expression and mutation of ARID1A.     

AgNOR staining in benign hyperplasia and carcinoma of the prostate.

We have modified existing techniques for silver staining of nucleolar organizer regions of intact interphase cells by hypotonic swelling and by formic acid treatment to reduce background staining. This allowed the microscopic identification and counting of individual AgNORs in the nucleoli. The method was used on nine adenomatous prostatic samples (including one of normal prostate tissue outside a localized tumor) and on seven prostatic adenocarcinomas. In general, the adenomatous samples displayed fewer AgNORs (mean 13 dots/cell) than did the carcinomas (mean 24 dots/cell). Although no cells with very high AgNOR counts were found in specimens from nonmalignant tumors, two of the adenomatous prostates did have AgNOR profiles that to a large extent overlapped with those of carcinomas. A highly differentiated carcinoma (of which only very small amounts were present in the sample) had low AgNOR counts. The three moderately differentiated carcinomas had more silver-positive material than the nonmalignant prostates but less than the three poorly differentiated carcinomas. The latter tumors also had a substantial proportion of cells with greater than 60 AgNOR counts, something that was never seen in carcinomas with higher differentiation. The data indicate that analysis of silver staining-positive material in intact interphase cells may help distinguish between benign and malignant prostatic tumors and between highly malignant and low malignant carcinomas.     

Ultraviolet carcinogenesis in athymic nude mice

We have investigated the development of skin cancer from exposure to ultraviolet (UV) radiation in C3H- nu/nu nude mice. Nude mice, nude mice reconstituted with thymuses, and nude mouse skin grafted onto normal haired mice had similar tumor incidences and rates of tumor development. All tumors were squamous cell carcinomas and both well-differentiated and poorly differentiated lesions occurred in each of the groups. Transplants of the tumors that developed in nude skin grew preferentially in immunosuppressed mice as compared with normal mice, indicating that tumors from each treatment group were antigenic. These results indicate that the presence or absence of a functioning thymus does not seem to influence UV carcinogenesis.     

Large de novo renal cell carcinoma in a 10-year-old transplanted kidney: successful organ-preserving therapy

BACKGROUND: A recent review of the Cincinnati Transplant Tumor Registry recorded 24 de novo renal cell carcinomas developing in renal allografts. However, late development of these tumors after transplantation is very rare. Only four reports exist regarding conservative surgery on kidney transplant tumors. METHODS: This is a report on a case of a large 6-cm de novo renal cell carcinoma in a 10-year-old transplanted kidney. Optimal therapy by transplant nephrectomy or tumor enucleation was discussed. RESULTS: Partial resections or enucleations of renal cell carcinoma are still less than ideal in carcinomas larger than 3 cm considering the higher risk of local recurrence. But the recipient in this case had done so well and had had such a high quality of life after transplantation that partial nephrectomy as therapy of choice was selected. Now the patient is 2 years tumor free. CONCLUSION: The case report demonstrates that in certain select cases of large tumors, organ-preserving surgery could be an alternative approach in combining complete tumor removal with preservation of graft function.     

Mucinous tumors of the ovary: a clinicopathologic study of 196 borderline tumors (of intestinal type) and carcinomas, including an evaluation of 11 cases with 'pseudomyxoma peritonei'

Mucinous ovarian neoplasms other than cystadenomas and adenofibromas have been classified as either borderline tumors or carcinomas for many years. Borderline tumors have been subdivided more recently into endocervical-like (mullerian) and intestinal forms. Such a distinction is rarely made in the mucinous carcinoma category. We did not encounter a pure endocervical-like carcinoma in the present series. Criteria for distinguishing an intestinal-type mucinous borderline tumor from a mucinous carcinoma have been controversial. In this study of 164 mucinous borderline tumors of intestinal type and 32 mucinous carcinomas, the former were further subdivided into 74 cases with epithelial atypia only and 90 with focal intraepithelial carcinoma. Of the 67 stage I tumors in the borderline (with atypia) category, all 49 with follow-up data were clinically benign; in the seven cases that had been designated stage III, the intraoperative appearance was that of "pseudomyxoma peritonei," which was fatal in four cases. Most of these tumors, however, were probably metastatic to the ovary rather than truly primary borderline tumors, although failure to examine the appendix in six cases compromised their interpretation. All 90 mucinous borderline tumors that had foci of intraepithelial carcinoma were recorded as stage I, but two of the 69 patients with follow-up data (3%) had fatal recurrences. Both of these tumors were incompletely staged, however, and one had ruptured intraoperatively. Thirty-two invasive carcinomas were subdivided into 12 expansile and 20 infiltrative subtypes; within the latter category seven tumors were only microinvasive. All 12 carcinomas with only expansile invasion were stage I; none of the 10 with follow-up data recurred. All seven microinvasive infiltrative carcinomas were stage I; none of the five with follow-up data recurred. One of five patients with stage I infiltrative carcinomas that were more than microinvasive and were adequately followed had a fatal recurrence, but staging had been incomplete in that case. Seven of the remaining eight infiltrative carcinomas were higher than stage I: five of the six (83%) with follow-up data persisted or recurred and were fatal. Considering all stages, increasing tumor grade in the carcinoma category correlated with an unfavorable outcome. However, grade did not influence prognosis in stage I carcinomas. Among 13 stage I cases in all categories with either preoperative or intraoperative tumor rupture and follow-up data, one recurred, a tumor in the borderline with intraepithelial carcinoma category. "Pseudomyxoma peritonei" is an ill-defined term and should not be used as a pathologic diagnosis. The presence of mucin in the abdominal cavity requires careful histologic evaluation to characterize it for prognostic purposes. Adequate and sometimes extensive sampling of mucinous ovarian tumors, the appendix and the peritoneum in cases of "pseudomyxoma peritonei" is necessary to achieve an accurate diagnosis and prognosis.     

Pituitary carcinoma: a clinicopathological review

Pituitary carcinomas are rare tumors; less than 100 well-documented cases have been reported to date. Such tumors are aggressive and associated with a high mortality rate. The molecular events leading to the development of pituitary carcinomas are largely unknown. Recent studies have only begun to shed light on the probable mechanisms of tumor initiation and progression. A review of the clinicopathological and molecular genetic characteristics of pituitary carcinomas is presented.     

Renal cell carcinoma vs. renal oncocytoma. Report of a case with overlap features and review of the literature

Although the salient features of renal oncocytomas and renal cell carcinomas have been discussed in the recent literature, renal masses with features of both entities will present diagnostic difficulty, especially when the cells are diffusely eosinophilic on microscopic examination. A case of a firm, tan, rounded mass replacing the lower pole of the kidney is discussed. The final diagnosis of renal cell carcinoma, granular cell type, was made after multiple sections of the tumor were examined, and after electron microscopy was performed. A thorough search by light microscopy should be made for clear cell foci, necrosis, mitotic activity, and vascular or capsular invasion, features generally accepted as pathognomonic for renal cell carcinoma. Cellular and especially nuclear pleomorphism is typically focal or mild in renal oncocytomas. True oncocytic tumors will be packed with mitochondria on electron microscopy; however, granular renal cell carcinomas will contain mitochondria as well as other cellular organelles, lipid, and glycogen. Electron microscopy should be performed on tumors suspected of being oncocytomas because eosinophilia on hematoxylin and eosin stain, as demonstrated by this case, is not a predictable measure of mitochondria content. Immunoperoxidase staining for vimentin in oncocytomas has recently been shown to be negative, and may offer a method of ruling out oncocytoma in vimentin-positive tumors, pending further studies.