Immunoreactivity For Epithelial Membrane Antigen Research Articles

RELA fusion-positive ependymoma accompanied by extensive desmoplasia: a case report

We report a case of 33-year-old Japanese male who presented with a headache and visual disturbances. Magnetic resonance imaging revealed a large tumor in the left frontal lobe, measuring 7cm in diameter, which was diagnosed as supratentorial anaplastic ependymoma accompanied by extensive desmoplasia. The patient underwent a gross total resection. Histologically, the tumor cells had oval or short, spindle-shaped nuclei, and proliferating cells in perivascular pseudorosettes with anucleate zones and mitotic figures. Desmoplasia with abundant collagen fibers among the tumor cells was detected at numerous sites, and perinuclear dot- or ring-like immunoreactivity for epithelial membrane antigen was identified. Five years and six months after the initial procedure, a small recurrent tumor was identified at the removal site. The patient underwent a second total resection. The histology of the resected tumor showed decreased collagen production and more apparent anaplastic features as compared to those of the initial tumor. In addition to the histological findings, molecular examinations revealed ependymoma, RELA fusion positive. Although not commonly observed, this case suggests that desmoplasia could be associated with ependymomas, including RELA fusion-positive variant. Moreover, our findings indicate that high-grade ependymoma requires careful, long-term follow-up even if gross total resection is performed.

Plexiform Schwannoma of the Oral Cavity: Report of Eight Cases and a Review of the Literature.

Plexiform schwannoma represents an unusual schwannoma variant, characterized by multinodular growth grossly and/or microscopically. A review of the English-language literature reveals only 28 previously reported cases involving the oral cavity, and herein we present 8 additional cases. Among these 36 patients, the average age at diagnosis was 28 years (range 5 to 62 years), with a female-to-male ratio of 1.4:1. The most frequently involved sites were the tongue (n = 13) and lip (n = 11). Lesion duration prior to presentation averaged 5.3 years (range, 6 weeks to 26 years). The average lesion size was 2.1 cm (range, 0.3 to 16 cm). The typical clinical presentation was a painless mass, although infrequent findings included pain/discomfort, paresthesia, difficulty chewing, and limited buccal mobility. All cases clinically appeared as a solitary mass or localized cluster of tumor nodules, with the exception of one patient who had neurofibromatosis 2 (NF2) and exhibited two distinct nodules on the tongue and buccal mucosa. In addition, extraoral neural neoplasms were evident in four patients, including three with NF2. Typical microscopic findings included multiple well-circumscribed tumor nodules, each surrounded by a perineurium-derived capsule with immunoreactivity for epithelial membrane antigen. The nodules contained characteristically bland and diffusely S-100-positive spindle cells arranged in Antoni A and B patterns; however, modest nuclear pleomorphism was evident in three cases. Most patients (n = 23) were treated by excision or enucleation and curettage, and three patients experienced recurrence. Unlike plexiform neurofibromas, plexiform schwannomas exhibit only a weak association with neurofibromatosis and have no known malignant potential.

1535 A Rare Case of Rectosigmoid Mucosal Schwann Cell Hamartoma

INTRODUCTION: Colorectal polyps of mesenchymal origin are rare. Mucosal Schwann cell hamartomas have a pure proliferation of Schwann cells in the lamina propria and show immunoreactivity to S-100 protein. To our knowledge, only 11 cases have been reported in the literature since it was first described in 2009. CASE DESCRIPTION/METHODS: We present a case of a 50-year-old African-American female who presented to us for routine screening colonoscopy. Her past medical history was only significant for a prolactinoma for which she was on cabergoline. The patient had no personal or family history of neural lesions or inherited syndromes such as NF1, Cowden syndrome or MEN 2B. The colonoscopy revealed a 2 mm polyp in the cecum and a 3 mm sized rectosigmoid polyp which were resected and sent to pathology. The cecal polyp showed a tubular adenoma. The pathology report for the rectosigmoid polyp was consistent with spindle-shaped lesional cells with immunohistochemical staining strongly positive for S-100. They did not have immunoreactivity for epithelial membrane antigen (EMA). Hence, supporting the diagnosis for Schwann cell hamartoma. The patient was made aware of pathology findings and reassured. DISCUSSION: Mucosal Schwann Cell Hamartoma is a rare and benign lesion that forms in the colon. It usually arises in older adults. The specific risk factors of Mucosal Schwann Cell Hamartoma are unknown. Most patients are asymptomatic however rectal schwannoma may cause symptoms such as obstruction, bleeding, and tenesmus. They are often found incidentally in the distal colon during a colonoscopy. These tumors are poorly circumscribed, with short fascicles of uniform spindle cells replacing the colonic lamina propria, especially the superficial lamina propria, and separating and entrapping the crypts. These tumors involve the mucosa but never the submucosa. Although the histological differential diagnosis of a mucosal Schwann-cell hamartoma can include a gastrointestinal stromal tumor (GIST), neurofibroma, mucosal neuroma, ganglioneuroma, or mucosal schwannoma, a mucosal Schwann-cell hamartoma is composed of single Schwann cells without other cells, such as axons or fibroblasts, and is uniformly stained for S-100. These cells do not have immunoreactivity for c-Kit, CD34, glial fibrillary acidic protein, epithelial membrane antigen (EMA), smooth muscle actin, or neurofilament protein (NFP). Due to the benign nature of Mucosal Schwann Cell Hamartoma, they do not generally require any treatment.

AN UNUSUAL BUMP ON THE HEAD: INTRAEXTRACRANIAL MENINGIOMA PRESENTING INCIDENTALLY

An 82–year–old gentleman presented to hospital following a fall. The patient had no recollection of the fall, and was found conscious sometime later on the floor by the neighbours. At...

Prominent EMA ‘dots’ in tumour‐induced Bergmann gliosis

To describe an unusual pattern of epithelial membrane antigen (EMA) immunoreactivity in highly proliferative human Bergmann glia. An immunohistochemical study was performed of postmortem cerebellar tissue from 18 adult patients with cerebellar damage of various aetiologies and 15 biopsies of diverse adult and paediatric cerebellar tumours. We observed marked proliferation of Bergmann glia with unusual prominent dot-like cytoplasmic EMA immunoreactivity in a case with extensive leptomeningeal sarcomatosis. Similar staining was not observed in association with other types of cerebellar pathology, except for other neoplastic conditions, such as leptomeningeal carcinomatosis, adult medulloblastoma, and pilocytic astrocytoma in children. At an ultrastructural level, the index case showed prominent endoplasmic reticulum with some intermediate filaments and lipofuscin granules, but no structures related to cilia or microvilli were observed. We consider that prominent EMA dots in Bergmann glia might represent excessive activation induced by an overlying leptomeningeal tumour that stimulates the expression of early developmental antigens. This observation suggests modulation of the glial phenotype when exposed to a neoplastic microenvironment that, in turn, might influence the regenerative potential of Bergmann glia.

Sclerosing Polycystic Adenosis of Salivary Glands: A Review with Some Emphasis on Intraductal Epithelial Proliferations

Sclerosing polycystic adenosis (SPA) is a rare condition of salivary glands. The most common site is the parotid gland (80 % of cases). SPA shows no gender predilection and occurs over a wide age spectrum (9-84 years). SPA is mostly unifocal, but may rarely be multifocal. Histologically, SPA are sharply circumscribed mostly unencapsulated lesions composed of acinar and ductal components with variable cytomorphological characteristics, including foamy, vacuolated, apocrine, mucous, clear/ballooned, squamous, columnar and oncocyte-like cells. Characteristic for SPA is the presence of large acinar cells with abundant eosinophilic cytoplasmic granules. The stroma is densely collagenized, frequently harbouring a variably intense chronic inflammatory infiltrate and may contain fat. Rarely the stroma is myxoid. Some degree of intraductal epithelial proliferations have been reported in at least 50 % of cases. The proportion of cases with epithelial proliferations that fulfill criteria for high-grade ductal carcinoma in-situ is <10 %. Immunohistochemically, both ductal and acinar cells are positive for broad spectrum cytokeratins. There is variable immunoreactivity for epithelial membrane antigen and S-100 protein. CEA, p53 and HER2 is reportedly negative. Gross cystic disease fluid protein-15 is strongly expressed in the acinar component. There is consistent but variable expression of estrogen and progesterone receptors. The proliferative index (Ki-67) is low (1-2 %) in the benign (acinar and ductal) components. Using HUMARA methodology (non-random inactivation of X-chromosomes), six cases with atypical epithelial proliferations have been shown to be clonal processes. Recurrences have been reported in up to 19 % of cases.

Superficial Acral Fibromyxoma on the Second Toe

Superficial Acral Fibromyxoma on the Second Toe

Bilateral cerebellar epithelioid hemangioblastoma with possible ependymal differentiation in a patient with von Hippel–Lindau disease

There are controversies regarding the histogenesis of stromal cells of hemangioblastoma, and no hypothesis has conclusively been proven. We report a case of unusual hemangioblastoma in a middle-aged man with von Hippel-Lindau disease. Neuroimaging revealed multifocal gadolinium-enhancing masses were located within both sides of the cerebellar hemisphere. Histologically, only small areas showing the typical morphology of hemangioblastoma were recognized in masses. Most areas of masses were composed of cohesive epithelioid tumor cells with abundant cytoplasm and distinct boundaries. Epithelioid tumor cells were arranged around blood vessels, exhibiting perivascular anuclear zone structures like ependymoma. The epithelioid tumor cells were diffusely positive for vimentin, CD99, neuron-specific enolase, GFAP and focally positive for epithelial membrane antigen (EMA) and D2-40 in a dot-like pattern. Variable-sized lipid droplets and glycogen particles were noted in the cytoplasm of epithelioid tumor cells under an electron microscope. A diagnosis of epithelioid cellular hemangioblastoma with possible ependymal differentiation (WHO grade I) was made. To our knowledge, only a few cases of hemangioblastoma show epithelioid appearance or EMA immunoreactivity. The present case indicates that the stromal cells of hemangioblastoma might originate from primitive neuroectodermal cells, and they have the capacity to show a distinctive sign of glial or ependymal differentiation.

A Soft Tissue Perineurioma and a Hybrid Tumor of Perineurioma and Schwannoma

Perineuriomas are composed of differentiated perineurial cells. Perineuriomas have been recently recognized by the immunoreactivity for epithelial membrane antigen (EMA). Microscopically, perineuriomas show proliferation of spindle cells with wavy nuclei and delicate elongated bipolar cytoplasmic processes. The tumor cells are usually negative for the S-100 protein. Ultrastructurally, perineurial cells reveal slender, nontapered processes containing pinocytic vesicles and discontinuous basal lamina. Interestingly, hybrid tumors of benign peripheral nerve sheath tumor (PNST) have been recently reported by using immunohistochemical and ultrastructural investigations. Herein, we report a case of soft tissue perineurioma arising in the skin of a 56-year-old female; another case of a hybrid tumor of perineurioma and schwannoma in the posterior mediastinum occurred in a 53-year-old male, which is the first case of the hybrid PNST tumor reported in Korea.

Lymphoplasmacyte‐rich meningioma: A convexity mass with regional enhancement in the adjacent brain parenchyma

Lymphoplasmacyte-rich meningioma (LPM) is a rare, benign variant of meningioma, characterized by massive inflammatory cell infiltration and a variable proportion of meningothelial tumorous elements. Here we report the clinicopathological features of an LPM located at the right frontal convexity in a 37-year-old woman. The patient had suffered an initial generalized tonic-clonic seizure when she was 32 weeks pregnant. The lesion exhibited low intensity on T1-weighted MRI and high intensity on T2-weighted images, with surrounding parenchymal edema. The mass exhibited gadolinium enhancement with dural tail signs. Moreover, multiple foci of linear enhancement spreading through the sulci and into the nearby brain parenchyma were evident. At 1 month after parturition, en bloc removal of the mass, the attached dura mater and adjacent brain tissue was performed. Histologically, the mass located in the subdural space was composed of a mixture of B- and T-lymphocytes and plasma cells. Within the mass, multiple small lobules of meningothelial cells showing immunoreactivity for epithelial membrane antigen and vimentin were observed. The inflammatory cells had also infiltrated the subarachnoid and Virchow-Robin spaces, and the dura mater. The cerebral cortex showed ischemic changes, but no tumor cell invasion. On the basis of these histological features, the lesion appeared to be LPM with an inconspicuous meningothelial component and extensive inflammatory infiltration. This case appears to provide useful information on the pathogenesis of this variant.

Diagnostic usefulness of EMA, IMP3, and GLUT‐1 for the immunocytochemical distinction of malignant cells from reactive mesothelial cells in effusion cytology using cytospin preparations

To differentiate reactive mesothelial cells (RMs) from metastatic carcinoma and malignant mesothelioma (MM) in effusion cytology is crucial for the cytologic diagnosis and the management of the patients. In the present study, the immunocytochemical staining profile of the epithelial membrane antigen (EMA), the insulin-like growth factor-II mRNA-binding protein 3 (IMP3), and the glucose transporter-1 (GLUT-1) was examined to distinguish RMs from malignant cells. A total of 171 pleural (n = 87) and peritoneal (n = 84) effusion specimens, including 50 benign effusions with RMs, 11 MM effusions, and 110 metastatic malignant effusions, were evaluated for immunocytochemistry. EMA, IMP3, monoclonal GLUT-1, and polyclonal GLUT-1 immunoreactivity were observed in 26.0%, 6.0%, 20.0%, and 18.0% of RMs, respectively. In contrast to RMs, the immunoreactivity in MM was 100%, 36.4%, 100%, and 90.9%; adenocarcinoma (AC) was 100%, 80.8%, 81.7%, and 72.1%; squamous-cell carcinoma was 83.3%, 83.3%, 83.3%, and 66.7%. EMA, IMP3, mGLUT-1, and pGLUT-1 expressions were observed in 98.4%, 65.6%, 88.5%, and 75.4% in the pleural effusion with malignant cells, and 100%, 88.3%, 78.3%, and 71.7% in ascites containing malignant cells, respectively. The findings of the present study indicate that the immunocytochemical staining for EMA, IMP3, and GLUT-1 is a useful diagnostic tool for distinguishing effusions containing malignant cells from those that contain benign cells, and in particular, we suggest that the combination of mGLUT-1 and EMA, and IMP3 and EMA are extremely useful in pleural effusion and in ascites, respectively.

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.

Expression of podoplanin and calretinin in meningioma: an immunohistochemical study

Meningioma is derived from arachnoid cells covering the surface of the brain and spinal cord, and it has characteristics shared by mesothelioma arising from the pleura and peritoneum in that it takes an epithelioid appearance despite its mesenchymal origin. We examined the immunohistochemical expression of podoplanin and calretinin, both of which are well-known markers of mesothelioma, in 24 surgical cases of meningioma of various types. In most cases, a linear immunoreactivity for podoplanin was found along the cell surface of most neoplastic cells. An intracytoplasmic, finely granular, or diffuse immunoreactivity was also noted in some cells. These findings corresponded well to immunoreactivity for epithelial membrane antigen (EMA), but immunoreactivity for podoplanin was more crisp or sharply delineated and clear compared with that for EMA. These findings indicate that podoplanin can be used as an immunohistochemical marker that is equivalent to EMA in the differential diagnosis of meningioma. However, most meningiomas did not contain calretinin-immunoreactive cells, a finding that differs from the diffuse immunoreactivity seen in mesothelioma.

Tanycytic ependymoma of the spinal cord with anaplastic cytological features

In a 43-year-old man, an intramedullary spinal cord tumor spreading from the level of the T2 to T5 vertebrae was subtotally resected. The tumor predominantly consisted of a fascicular proliferation of spindle cells having bland nuclei and bipolar, long cytoplasmic processes, and a few perivascular pseudo-rosettes were found. Although there were no true ependymal rosettes, intracytoplasmic dot-like immunoreactivity for epithelial membrane antigen (EMA) was found in a few cells. In some areas, a dense and diffuse proliferation of anaplastic, short-spindled cells having hyperchromatic nuclei and scant cytoplasm was noted, and the Ki-67 labeling index was remarkably higher (18.2%) in these areas. Neither microvascular proliferation nor necrosis was observed. In the boundary region, these two areas showed gradual transition from one to the other. The patient has remained free from recurrence for 10 months postoperatively. This is the first documentation of tanycytic ependymoma in which tumor cells showed anaplastic cytological features.

Sebaceous Epithelial-Myoepithelial Carcinoma of the Salivary Gland: Clinicopathologic and Immunohistochemical Analysis of 6 Cases of a New Histologic Variant

Epithelial-myoepithelial carcinoma (EMC) of the salivary glands is an uncommon, low-grade malignant tumor. A recent report demonstrates sebaceous differentiation in this tumor even though its significance has never been documented as a precise histologic variant. Six cases of EMC exhibiting sebaceous differentiation (sebaceous EMC) of the parotid gland were analyzed for their clinicopathologic features and immunohistochemical characteristics. In addition, primary salivary sebaceous carcinomas were also examined for comparison. In our series, the incidence of sebaceous EMC was 0.2% among 3012 cases of parotid gland tumors and 14.3% of all EMC cases. The 6 patients comprised 2 men and 4 women, age ranging from 77 to 93 years (mean, 83.7 y). Neither cervical lymph node nor distant organ metastases were found in any cases of sebaceous EMC and no patients died of disease, though local recurrences developed in 1 patient. Conversely, cervical lymph node metastasis was detected in 2 of 3 patients with sebaceous carcinoma, 1 of whom died of disease at 12 months. Histologically, all 6 tumors had an area of sebaceous differentiation admixed with features of bilayered ductal structures typical of EMC. A component of sebaceous differentiation was distributed diffusely in 4 tumors and focally in 2. Cytologic atypia of sebaceous EMCs was lesser than that of sebaceous carcinomas. Immunohistochemically, putative myoepithelial markers such as alpha-smooth muscle actin, calponin, p63, cytokeratin 14, S-100 protein, and vimentin were highly expressed in sebaceous EMC. However, the expression of the latter 4 markers was also observed in primary sebaceous carcinomas, whereas these tumors were all negative for alpha-smooth muscle actin and calponin. Positive immunoreactivity for epithelial membrane antigen, adipophilin, and perilipin confirmed sebaceous differentiation in EMC. These results indicate that sebaceous EMC is a low-grade malignancy, similar to conventional EMC. Our data also suggest that immunohistochemical examination of specific myoepithelial markers is helpful in distinguishing sebaceous EMC from sebaceous carcinoma, which may occasionally be associated with an aggressive clinical course.

Cytokeratin and Epithelial Membrane Antigen Expression in Angiosarcomas: An Immunohistochemical Study of 33 Cases

Expression of epithelial cell markers can occur in mesenchymal tumors and has been reported in angiosarcomas with variable frequency. In these situations, establishing the diagnosis becomes problematic. To determine the expression of cytokeratin and epithelial membrane antigen in angiosarcoma. To address this issue, 33 well-documented cases of angiosarcomas were retrieved from the archival material of Shands Hospital at the University of Florida, Gainesville, and Jackson Memorial Hospital at the University of Miami, Miami, Florida. These cases were all reviewed and studied using a cytokeratin cocktail (CAM 5.2 and AE1/AE3) and epithelial membrane antigen using standard immunohistochemical techniques. All 33 cases had available material for cytokeratin analysis; however, only 20 cases had enough material for epithelial membrane antigen staining. In the 33 cases studied, the age range of the patients was 2 to 88 years (mean, 63 years). There were 23 (70%) men and 10 (30%) women. One (3%) of 33 was cytokeratin-immunoreactive and 2 (10%) of 20 were epithelial membrane antigen-immunoreactive. Cytokeratin and epithelial membrane antigen immunoreactivity in angiosarcomas is infrequent but may be encountered. Interpretation of such expression should be done with caution and in conjunction with the characteristic clinical and morphologic features of the tumor as well as the expression of endothelial cell antigens.

Immunohistochemical profile and chromosomal imbalances in papillary tumours of the pineal region

The histopathology of papillary tumours of the pineal region (PTPR) closely resembles that of ependymomas and choroid plexus tumours. Therefore, immunohistochemical staining profiles were investigated in a series of 15 PTPR. In addition to cytokeratin, synaptophysin and glial fibrillary acidic protein expression, PTPR were examined for the presence of dot- or ring-like epithelial membrane antigen (EMA) immunoreactivity typically encountered in ependymoma, staining for inwardly rectifying potassium channel Kir7.1 and stanniocalcin-1 (specifically expressed in choroid plexus tumours) as well as microtubule-associated protein-2 (MAP-2). Furthermore, comparative genomic hybridization was performed in five PTPR. Cytokeratin was expressed in all PTPR examined, whereas glial fibrillary acidic protein and synaptophysin staining were absent. Dot- or ring-like EMA immunoreactivity was only observed in 1 out of 15 PTPR. Membranous Kir7.1 and cytoplasmic stanniocalcin-1 staining were present in the minority of PTPR (3/15 and 4/15, respectively). In contrast, MAP-2 immunoreactivity was encountered in 13 out of 15 PTPR, but was significantly less frequently observed in a series of choroid plexus tumours (7/37). PTPR mainly presented with chromosomal losses affecting chromosomes 10 (4/5 cases) and 22q (3/5 cases) as well as gains on chromosomes 4 (4/5 cases), 8 (3/5 cases), 9 (3/5 cases) and 12 (3/5 cases). To conclude, the majority of PTPR can be distinguished from ependymomas and choroid plexus tumours by absent staining for epithelial membrane antigen, Kir7.1 and staniocalcin-1 as well as the presence of distinct MAP-2 immunoreactivity. Antibodies directed against these antigens are thus expected to be valuable markers in the diagnosis of papillary tumours located in the vicinity of the third ventricle.

Desmoplastic Small Round Cell Tumor: A Case Report

Desmoplastic small round cell tumor (DSRCT) is a rare and highly malignant mesenchymal tumor found in the abdominal cavity. It mainly affects young male patients. We report a case of DSRCT that occurred in the abdominal cavity of a 50-year-old man. The tumor was characterized by small round tumor cells with irregular nests in the prominent desmoplastic stroma. The tumor cells showed immunoreactivity for epithelial membrane antigen, desmin, vimentin, and neuron specific enolase.

Pituicytoma incidentally found at autopsy

Pituicytoma is a rare benign neoplasm, occurring in the sellar and suprasellar regions. Reported herein is a case of asymptomatic pituicytoma, discovered at autopsy, in a 54-year-old Japanese woman. This is the first case report of pituicytoma, found incidentally at autopsy (incidentaloma), in which whole-mounted sections are available for histological and immunohistochemical studies. Grossly, the bisected pituitary gland revealed a round, white to light tan, 7 mm-diameter nodule. Microscopically, whole-mounted sections revealed a well-circumscribed nodule with no fibrous capsule, located mainly in the neurohypophysis and partially compressing the adenohypophysis. The tumor was composed primarily of bipolar, occasionally unipolar, cells with syncytial fibrillary cytoplasm, arranged in short curvilinear fascicles and/or storiform patterns. Unusual histological features were seen, which included a few groups of large pleomorphic tumor cells with abundant, glassy, eosinophilic cytoplasm, occasionally associated with multinucleated giant tumor cells, and scattered Herring bodies within the tumor. Immunohistochemically, the tumor showed diffuse strong expression of glial fibrillary acidic protein, S-100 protein, and vimentin. Epithelial membrane antigen immunoreactivity was focally observed, mainly in the large tumor cells. Distinction from other intrasellar tumors (granular cell tumor and pilocytic astrocytoma) is important. Because the immunohistochemical profiles of these tumors are similar, histological findings are crucial for distinction.

Usefulness of epithelial membrane antigen (EMA) to discriminate between perineural invasion and perineural indentation in prostatic carcinoma

Perineural invasion (PNI) is one of the few unequivocal criteria to diagnose adenocarcinoma of the prostate. Distinguishing PNI from perineural indentation (PNIn), however, is sometimes difficult. The aim of this study was to discriminate between PNI and PNIn using EMA immunohistochemistry. We selected representative sections from 87 prostatectomies with prostatic adenocarcinoma. Normal peripheral nerves were continuously encircled with perineurium, which was immunoreactive for EMA. We identified 1319 PNI by carcinomas, 368 PNIn by carcinomas, and 303 PNIn by benign glands. We categorized the EMA immunoreactivity patterns into three classes: samples that displayed discontinuity or complete loss of the perineurium (Type A), samples where there were carcinomas or benign glands in the perineural space or peripheral nerves (Type B) and samples that showed no changes in the perineurium (Type C). For PNI we observed Type A, Type B, and Type C patterns in 55.3%, 24.8% and 19.9% of carcinomas, respectively. The incidence of each of those patterns in PNIn by carcinomas was 32.1%, 14.9% and 53.0%, respectively. Cases of PNIn by benign glands showed Type A or Type C patterns. They did not, however, exhibit Type B patterns. EMA immunostaining will aid the diagnosis of prostatic adenocarcinoma.