CD10: A Review

CD10 (neprilysin) expression: a potential adjunct in the distinction of hibernoma from morphologic mimics

Although the morphologic diagnosis of hibernoma is usually straightforward, some hibernomas have atypical morphologic features, mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLs). In addition, the multivacuolated brown fat cells may be mistaken for lipoblasts by pathologists, especially those without significant soft tissue tumor exposure. Thus, we continue to receive in consultation cases of hibernoma sent for MDM2 fluorescence in situ hybridization testing to exclude ALT/WDL. Testing hibernomas for MDM2 amplification, however, adds cost and delays the final diagnosis. Recently, we have noted expression of neprilysin (CD10, CALLA), a zinc-dependent metalloproteinase involved in the inactivation of various peptide hormones, in brown fat cells, and wished to explore the potential utility of this widely available, inexpensive ancillary test in the differential diagnosis of hibernoma. Formalin-fixed, paraffin-embedded tissue sections from well-characterized cases of hibernoma (n = 48), brown fat (n = 21), ALTs/WDLs (n = 17), pleomorphic liposarcomas (PLPSs) (n = 6), lipomas (n = 5), and fat necrosis (n = 5) were immunostained for CD10, using a commercially available antibody and routine laboratory protocols. CD10 expression was evaluated in both adipocytes and in surrounding stromal cells. The hibernomas occurred in 28 men and 20 women, ranging from 11 to 76 years of age and involved the extremities (n = 25), pelvis (n = 7), abdomen/pelvis/retroperitoneum (n = 7), head and neck region (n = 6), back (n = 2), and chest (n = 1). All showed diffuse, strong CD10 expression in multivacuolated brown fat cells and in the majority of adjacent univacuolated fat cells. Brown adipose tissue from various anatomic structures showed an identical pattern of immunoreactivity. In contrast, CD10 expression was present in the adipocytes of only 3 of 17 (18%) ALTs/WDLs and was absent in lipomas and fat necrosis. Lipoblasts expressed CD10 in 3 PLPSs. Expression of CD10 by surrounding fibroblastic stromal cells was more widespread, present in 13 hibernomas, 10 ALTs/WDLs, 1 instance of fat necrosis, 6 PLPSs, and 4 examples of brown fat. We conclude that immunohistochemistry for CD10 may represent a useful, rapid and inexpensive ancillary test in the differential diagnosis of hibernoma from potential morphologic mimics, especially when morphologic features favor hibernoma. CD10 expression in adipocytes, however, should be rigorously distinguished from fibroblastic stromal cell CD10 expression, a nonspecific finding.

Clinicopathological and molecular markers associated with prognosis and treatment effectiveness of endometrial stromal sarcoma: a retrospective study in China

Purpose

To evaluate the clinicopathological and immunophenotypic characteristics of endometrial stromal sarcoma (ESS) in China.

Methods and materials

Seventy-two consecutive ESS cases treated between 1995 and 2009 were retrospectively reviewed.

Results

Sixty-three patients received surgical treatment. Forty-one patients underwent pelvic lymphadenectomy. In paraffin-embedded specimens, expression of the following molecular markers was detected: CD10 (27/36), vimentin (37/38), HHF35 (3/32), S-100 (0/25), desmin (2/29), CD117 (0/23), CD34 (2/24), alpha-inhibin (0/17), CK (1/34), CD99 (4/9), smooth muscle actin (5/25), EMA (0/7), estrogen receptor (13/16) and progesterone receptor (13/16). CD10 and vimentin were expressed more frequently in these specimens. Tumor classification, CD10 and surgical procedures were significantly associated with disease-free survival (DFS). Surgical procedures were significantly associated with overall survival (OS). Tumor stage (P = 0.024) and surgical procedure (P = 0.042) were found to be significant independent prognostic factors for DFS. No complete or partial response was observed among patients who received radiotherapy or chemotherapy.

Conclusions

Our results indicate that total hysterectomy with bilateral salpingo-oophorectomy followed by pelvic lymphadenectomy is associated with an improved treatment outcome. CD10-negative expression may contribute to the malignant characteristics and recurrence associated with ESS.

Use of CD10 as a marker of canine mammary myoepithelial cells

CD10 is an important cell marker in the diagnosis of acute lymphoblastic leukaemia and of breast myoepithelial (ME) cells in humans. The objective of this study was to assess the value of CD10 as a marker of canine ME cells using immunohistochemistry on routinely processed normal, dysplastic and neoplastic mammary tissue. Five different CD10 positive cell types were identified on the basis of cell morphology, pattern of immunoreactivity, and on the co-expression of additional cell lineage-specific markers. Type 1 cells were typical fusiform cells with a ME cell phenotype (calponin- and cytokeratin [CK] 14-positive, CK8/18-negative). Type 2 cells were typical or atypical polyhedral cells with a luminal epithelial (LE) cell phenotype (calponin- and CK14-negative, CK8/18-positive). Type 3 cells had a type 1 phenotype with variable morphology, and type 4 were atypical neoplastic cells with a mixed ME/LE phenotype. Type 5 cells were typical fusiform cells with a stromal phenotype. Type 1 cells were considered normal ME cells and were found in all sample types; type 2 cells were considered normal or neoplastic LE cells and were also found in all sample types; types 3 and 4 cells were restricted to tumour samples and to malignant tumours, respectively, and type 5 cells were found in all sample types, although predominantly in neoplastic tissue. The findings indicate that the CD10 antigen is a sensitive (although not specific) marker of canine ME cells in normal, dysplastic and neoplastic mammary tissue. Differences in the distribution and staining intensity of CD10-positive cells suggest a number of potential roles for this protein in the pathogenesis of canine mammary neoplasia.

The utility of immunohistochemistry for the identification of hematopoietic and lymphoid cells in normal tissues and interpretation of proliferative and inflammatory lesions of mice and rats

Expression of antigens in cells and tissues can be readily studied immunohistochemically with the use of antibodies. A panel of antibodies to cell-specific markers can be used to diagnose lesions, including tumors, in the hematopoietic and lymphoid systems. This review discusses the use of readily available antibodies and procedures to identify antigens expressed in normal tissues and in proliferative and inflammatory lesions in formalin-fixed, paraffin-embedded (FFPE) murine specimens.

Clinicopathologic analysis of peripheral T-cell lymphoma, follicular variant, and comparison with angioimmunoblastic T-cell lymphoma: Bcl-6 expression might affect progression between these disorders

We examined clinicopathologic findings in 17 cases of peripheral T-cell lymphoma, follicular variant (f-PTCL), and compared these findings with angioimmunoblastic T-cell lymphoma (AITL) to determine whether they were identical to the spectrum of changes seen in AITL and how each of the findings in f-PTCL were related to the characteristics of AITL. Almost all f-PTCL cases showed pathologic characteristics of AITL and immunohistochemical positivities in lymphoma cells for CD4, CD10, Bcl-6, PD-1, and CXCL13. Except for pathologic characteristics, clinicopathologic findings in f-PTCL had few significant differences from AITL. The positive rate for Bcl-6 expression in neoplastic cells was significantly associated with the frequency of polymorphic infiltrates, vascular proliferation, B-immunoblasts, clear cells, Epstein-Barr virus-positive lymphocytes, hepatosplenomegaly, and skin rash. Our study confirmed the continuity between f-PTCL and AITL. Moreover, Bcl-6 expression in f-PTCL was statistically associated with the characteristics of AITL.

CD10 immunohistochemistry stains enteric mucosa, but negative staining is unreliable in the setting of active enteritis

Ileal pouch-anal anastomosis is the definitive therapy for ulcerative colitis that is refractory to medical treatment or that has developed neoplasia. Patients with this procedure are routinely followed using directed endoscopic biopsies to monitor for dysplasia in the rectal cuff, residual/recurrent ulcerative colitis, and nonspecific acute inflammation of the ileal pouch (pouchitis), which have different clinical management and outcomes. Thus, accurate localization of mucosal biopsies is crucial to a definitive histological diagnosis, but is complicated by overlapping clinical presentations of pouchitis and ulcerative colitis, post-surgical and inflammatory changes to the mucosa, and altered endoscopic anatomy, resulting in difficulty determining whether a mucosal biopsy is ileal or rectal in origin for both the endoscopist and the pathologist. We explored the utility of CD10 immunohistochemistry to aid diagnosis in this clinical setting by highlighting the enteric mucosa, based on previous studies showing its utility in brush border staining and in the diagnosis of microvillous inclusion disease. We found uniformly positive CD10 immunostaining in normal enteric mucosa, but variable loss of expression in the setting of active enteritis. Specifically, CD10 staining was lost in up to 10% of the mucosa in 1/12 ileostomies and 4/13 enteric anastomoses, in 10-80% of the mucosa in 9/10 cases of Crohn's ileitis, in 10-60% of the mucosa in 7/16 ileal pouches, and in 20-90% of the mucosa in 6/8 cases of backwash ileitis, usually in the presence of active inflammation. There was no CD10 expression by normal or diseased colonic mucosa. Therefore, while CD10 immunostaining identifies normal enteric mucosa with 100% specificity, negative staining does not definitively exclude small intestinal mucosa in the setting of active enteritis, a common condition in ileal pouch mucosa.

Prolymphocytoid transformation of follicular lymphoma with coexpression of CD5 and CD10

Histologic transformation of follicular lymphoma is usually to a diffuse large B-cell lymphoma. We present a rare example of a histologic transformation of follicular lymphoma manifested by prolymphocytoid morphology and an unusual immunophenotype characterized by coexpression of CD5 and CD10. The transformed prolymphocytoid lymphoma was positive for CD5 and CD10 antigens by both flow cytometry and immunohistochemistry. The case also expressed bcl-2 and bcl-6 proteins, and exhibited t(14;18), consistent with derivation from a pre-existing follicular lymphoma. Polymerase chain reaction analysis of the immunoglobulin kappa light chain genes derived from the follicular lymphoma and prolymphocytoid lymphoma showed identical rearranged bands, suggesting clonal identity of the two neoplasms. The basis for coexpression of CD5 and CD10 remains unclear. Because the preceding low-grade follicular lymphoma was positive only for CD10 and did not express CD5, CD5 expression appears to be an acquired phenomenon accompanying the process of histologic transformation in this particular case. Prolymphocytoid transformation, similar to other histologic forms of transformation of follicular lymphoma, appears to accompany clinical progression of disease.

B-cell differentiation immunophenotypes in classical Hodgkin lymphomas

The bcl6/CD10/MUM1/CD138 B-cell differentiation immunophenotypes were analysed in 101 cases of classical Hodgkin lymphomas (cHL) aiming to elucidate their histogenesis. Three major bcl6/CD10/MUM1/CD138 immunophenotypes were distinguished on the basis of the immunohistochemical positivity of Hodgkin and Reed-Sternberg (H/RS) cells: (a) the late germinal center (GC)/early post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138-); 59/101 cases (59%), (b) the post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138+); 24/101 cases (24%) and (c) the indeterminate immunophenotype (bcl6+/CD10-/MUM1+/CD138-: 14 cases and bcl6+/CD10-/MUM1+/CD138+: four cases); 18/101 cases (18%). The above findings indicate that H/RS cells in most cHL display bcl6/CD10/MUM1/CD138 immunophenotypes consistent with late GC/early post-GC or post-GC B-cell differentiation. In addition, H/RS cells in a small fraction of cHL display indeterminate bcl6/CD10/MUM1/CD138 immunophenotypic profiles which are characterized by simultaneous expression of GC, late GC/early post-GC and post-GC B-cell differentiation proteins. These immunophenotypic profiles do not correspond to the differentiation immunophenotypes of normal B-cells and their identification in a part of cHL suggests that the differentiation process of H/RS cells is not complete in a fraction of these cells and/or is still ongoing at the time of observation.

Best practices in contemporary diagnostic immunohistochemistry: panel approach to hematolymphoid proliferations

CONTEXT

The complexities of diagnostic hematopathology in the modern era are well known, and even in this molecular era, immunophenotypic studies, together with routine histopathology, remain a critical component in the evaluation of many lymphoid proliferations. With numerous antibodies that can be used on routinely fixed, paraffin-embedded tissue sections, immunohistochemistry has become increasingly valuable. It then becomes a challenge knowing the best approach to the selection of antibodies to use and how to interpret them.

OBJECTIVE

To present a pragmatic immunohistochemical approach to the evaluation of lymphoid proliferations that stresses the utility of 2 limited panels to deal with the most commonly encountered lymphomas.

DATA SOURCES

English-language literature published between 1990 and 2008.

CONCLUSIONS

A relatively limited panel of immunohistochemical stains may be used to diagnose and subclassify many of the more common lymphomas, although some cases will require additional stains and others fewer, depending on the case complexity. Immunohistochemical stains must always be interpreted in the context of the histopathologic and other ancillary studies.

Renal cell carcinoma marker reliably discriminates central nervous system haemangioblastoma from brain metastases of renal cell carcinoma

AIMS

The distinction between central nervous system (CNS) metastases of clear cell renal cell carcinoma (RCC) and CNS haemangioblastoma still poses a challenge to the pathologist. Since both entities occur in von Hippel-Lindau disease, this aggravates the issue. The antibody renal cell carcinoma marker (RCC-ma) has been suggested to identify primary RCCs specifically, but its value for diagnosing metastases of RCC is controversial. The aim was to assess two distinct clones of the RCC-ma for their potential to: (i) identify primary RCCs and (ii) differentiate between CNS metastases of clear cell RCC and CNS haemangioblastomas.

METHODS AND RESULTS

Using tissue microarrays, 77% (n = 363; PN-15) and 66% (n = 355; 66.4C2) of clear cell RCCs, and 93% (PN-15) and 74% (66.4C2) of papillary RCCs (n = 46) were immunopositive for RCC-ma, whereas none of the investigated chromophobe RCCs (n = 22) or any of the oncocytomas (n = 15) showed immunoreactivity. Importantly, 50.9% of CNS metastases of clear cell RCCs (n = 55) exhibited RCC-ma expression, whereas all CNS haemangioblastomas (71) were negative.

CONCLUSIONS

Both RCC-ma clones, despite some variation in their sensitivity to detect clear cell and papillary RCCs, are of value in differentiating subtypes of primary RCC and are excellent markers for discriminating clear cell lesions in the brain.

CD10 expression in tumour and stromal cells of bladder carcinoma: an association with bilharziasis

CD10 is a cell surface zinc metalloprotease expressed in a variety of normal cell types, including lymphoid precursor cells, germinal centre B lymphocytes and some epithelial cells. The aim of this study was to assess the prognostic value of CD10 in bladder carcinoma. The expression of CD10 was immunohistochemically assessed in 49 cases of primary bladder carcinoma in comparison with 10 non-neoplastic normal bladder mucosa specimens. 27 cases (55%) were tumour CD10(+) and tumour CD10 positivity was significantly correlated with advanced stage, larger tumor size, and shorter mean survival time. Extensive tumoral staining assessed by H score further documented the positive correlation of CD10 with worse prognostic factors in the whole group and its subdivisions (SCC and TCC), in addition to its significant association with bilharziasis in SCC. Only CD10-tumour positivity in the whole group proved to be an independent prognostic factor for overall survival by multivariate analysis. No significant value of stromal CD10 expression in the investigated bladder carcinoma cases was found. This study points to the prognostic value of neoplastic CD10 expression in bladder carcinoma and its possible importance in facilitating tumour invasion and metastasis. Bilharziasis could have a role in upregulation of CD10 expression in SCC.

CD10 Expression in Cutaneous Adnexal Neoplasms and a Potential Role for Differentiating Cutaneous Metastatic Renal Cell Carcinoma

Context.—Recent investigations have demonstrated the utility of CD10 as a marker for renal cell carcinoma (RCC). Cutaneous metastases occur in up to 11% of patients with RCC and may be the presenting sign of widespread disease. The differential diagnosis in histopathologic evaluation of these cases includes cutaneous adnexal neoplasms, and describing the expression of CD10 in these tumors may be helpful in delineating the differential diagnosis.

Objective.—To determine CD10 expression in a variety of adnexal lesions and to determine the diagnostic utility of CD10 in an immunohistochemical panel differentiating metastatic cutaneous renal cell carcinoma from cutaneous adnexal neoplasms.

Design.—We studied 57 primary adnexal neoplasms of eccrine (n = 31), apocrine (n = 16), and sebaceous (n = 10) differentiation as well as normal skin (n = 3) and RCC metastatic to the skin (n = 4). A CD10 monoclonal antibody was applied to formalin-fixed, paraffin-embedded tissue. Specimens were randomized and categorized as immunopositive or immunonegative by a pathologist with expertise in immunohistochemistry who was blinded to the diagnoses.

Results.—Two (6.5%) of 31 eccrine, 1 (6%) of 16 apocrine, and 4 (40%) of 10 sebaceous neoplasms demonstrated CD10 immunopositivity. Four (100%) of 4 RCC were CD10 immunopositive. CD10 expression was significant for eccrine and apocrine neoplasms (P < .001) compared to metastatic RCC, but not for sebaceous neoplasms (P = .08).

Conclusion.—Based on these results, CD10 is a useful additional immunostain for the discrimination of RCC metastatic to the skin and cutaneous adnexal neoplasms with eccrine and apocrine differentiation, but not with sebaceous differentiation.

[Expression of CD10 and renal cell carcinoma marker in clear cell renal cell carcinoma: analysis on tissue arrays]

OBJECTIVES

CD10 and renal cell carcinoma (RCC) marker antibodies react against proteins of the epithelium of the renal proximal tubule, being expressed by renal cell carcinomas. The frequence and pattern of expression of both markers are analysed in a series of clear cell renal cell carcinomas.

METHOD

Two tissue arrays were used, which were composed of cylinders obtained with a 16G needle from 40 paraffin blocks that corresponded to clear cell renal cell carcinomas. The labeled streptavidin-biotin technique was performed (LSAB2, Dako) using CD10 and RCC monoclonal antibodies (Novocastra), testing different antigen retrieval methods for RCC. Immunoreactivity was evaluated as + (isolated cells or focal staining); ++ (moderate) and +++ (extense).

RESULTS

Thirty cases (75%) were positive for CD10: 12 +; 5 ++ and 13 +++. The best antigen retrieval method for RCC was a double enzyme digestion (trypsin + protease). Twenty cases (50%) were positive for RCC: 7 +; 5 ++ and 8 +++. Four cases out of the 20 immunoreactive for RCC were negative for CD10. The 16 remaining cases also expressed CD10.

CONCLUSIONS

CD10 and RCC are often expressed by clear cell renal cell carcinomas, and they may be useful markers to suggest a renal origin of carcinomas. RCC is less sensitive than CD10. Staining for both of them is usually focal, and thus sensitivity of these techniques decreases when small samples are investigated, such as tissue arrays. The antigen retrieval method is essential for RCC immunohistochemical detection, obtaining the best results with the use of proteolytic enzymes.

Programmed death-1 (PD-1) is a marker of germinal center-associated T cells and angioimmunoblastic T-cell lymphoma

Programmed death-1 (PD-1), a member of the CD28 costimulatory receptor family, is expressed by germinal center-associated T cells in reactive lymphoid tissue. In a study of a wide range of lymphoproliferative disorders, neoplastic T cells in 23 cases of angioimmunoblastic lymphoma were immunoreactive for PD-1, but other subtypes of T cell and B cell non-Hodgkin lymphoma, as well as classic Hodgkin lymphoma, did not express PD-1. The pattern of PD-1 immunostaining of neoplastic cells in angioimmunoblastic lymphoma was similar to that reported for CD10, a recently described marker of neoplastic T cells in angioimmunoblastic lymphoma. Tumor-associated follicular dendritic cells in cases of angioimmunoblastic lymphoma were found to express PD-L1, the PD-1 ligand. In addition, PD-1-positive reactive T cells formed rosettes around neoplastic L&H cells in 14 cases of nodular lymphocyte predominant Hodgkin lymphoma studied. These findings, along with data from previous studies, suggest that angioimmunoblastic lymphoma is a neoplasm of germinal center-associated T cells and that there is an association of germinal center-associated T cells and neoplastic cells in nodular lymphocyte predominant Hodgkin lymphoma. PD-1 is a useful new marker for angioimmunoblastic lymphoma and lends further support to a model of T-cell lymphomagenesis in which specific subtypes of T cells may undergo neoplastic transformation and result in specific, distinct histologic, immunophenotypic, and clinical subtypes of T-cell neoplasia.

CD10 Expression in Urothelial Bladder Carcinomas: A Pilot Study

OBJECTIVES

The aims of this study were to investigate the expression of CD10 in normal bladder tissue and urothelial bladder carcinomas and to clarify its association with histopathological variables.

MATERIALS AND METHODS

A total of 79 urothelial bladder carcinomas were selected from routine archival material. All cases were reevaluated histopathologically and graded according to the World Health Organization (WHO) 1973, WHO/ISUP 1998, and WHO 1999 systems. The TNM system was used for their pathological staging. CD10 immunohistochemical staining was performed in selected slides.

RESULTS

Tumoral cases consisted of 74 men (93.7%) and 5 women (6.3%). According to the pathological stage, 25 (31.6%), 33 (41.8%), and 21 (26.6%) cases had pTa, pT1, and pT2-3 carcinomas, respectively. 34 of 79 (43%) urothelial carcinomas and only 1 of 11 (9.1%) nontumoral cases showed positive CD10 immunostaining. It was a cytoplasmic diffuse or granular immunostaining pattern both in nontumoral and tumoral urothelia. There was no statistically significant difference between tumoral and nontumoral cases with respect to CD10 reactivity (p = 0.051), but there was a trend toward significance. In urothelial tumors, there was a significant inverse correlation between pathological stages and CD10 immunoreactivity (p = 0.036, r = -0,237). There was also a statistically significant difference between pTa and pT2-3 urothelial tumors in relation to the CD10 expression (p = 0.034). No association was detected between CD10 expression and grades according to all systems used (p > 0.05).

CONCLUSIONS

According to our findings, the CD10 expression in noninvasive carcinomas showed a higher level than that in invasive carcinomas, and it is inversely correlated with the pathological stage. CD10 may play an important role in the progression of urothelial bladder carcinomas, and downregulation probably facilitates invasion, especially muscle invasion.

Human pancreatic mucinous cystadenoma is characterized by distinct mucin, cytokeratin and CD10 expression compared with intraductal papillary-mucinous adenoma

AIMS

To examine cytokeratin, epithelial glycoprotein (mucin) and glycoprotein CD10 expression in benign mucinous cystdenomas (MCAs) in comparison with intraductal papillary mucinous adenomas (IPMAs).

METHODS AND RESULTS

Thirty MCAs of the pancreas were analysed for immunohistochemical expression of cytokeratin (CK) 7, CK20, MUC1, MUC2, MUC5AC and CD10 and were compared with 16 IPMAs. CK7 was expressed in all neoplasms. CK20 was significantly more frequent in MCAs compared with IPMAs (56.66% versus 18.75%, P = 0.027). MUC1 was more frequent in MCAs (40% versus 12.5%, P = 0.0915), whereas MUC5AC was significantly less frequent in MCAs (33.33% versus 100%). MUC2 was expressed in goblet cells of seven MCAs. In MCAs, CD10 was observed both in epithelial cells and in the ovarian-type stromal cells (24/30). Epithelial expression of CD10 was significantly lower in IPMAs (66.66% versus 6.25%, p = 0.0001).

CONCLUSIONS

MCA is characterized by a significantly greater frequency of expression of CK20 and CD10 when compared with IPMA, which preferentially expresses MUC5AC.

Immunohistochemical Diagnosis of Epithelioid Mesothelioma: An Update

Objective.—Several new immunohistochemical markers that can assist in the diagnosis of mesotheliomas have been recognized recently. This article reviews the current information available on these markers and also provides a practical approach to the immunohistochemical diagnosis of epithelioid mesotheliomas.

Data Sources.—Current literature concerning immunohistochemical markers for epithelioid mesotheliomas was collected and reviewed.

Study Selection.—Literature emphasizing immunohistochemical diagnosis of epithelioid mesotheliomas was selected.

Data Extraction.—Data deemed helpful to the general surgical pathologist for the diagnosis of epithelioid mesothelioma were included in this review.

Data Synthesis.—Markers identified as potentially useful in the diagnosis of epithelioid mesothelioma include positive markers (namely, calretinin, keratin 5/6, D2-40, podoplanin, mesothelin, and Wilms tumor 1 protein [WT1]) and negative markers (namely, carcinoembryonic antigen, MOC-31, B72.3, and Ber-EP4). Thyroid transcription factor 1 (TTF-1) can assist in determining the lung origin of a carcinoma, and renal cell carcinoma marker (RCC Ma) may help establish its renal origin.

Conclusions.—D2-40 and podoplanin are the 2 most recently recognized markers that have been found to be useful in the diagnosis of epithelioid mesotheliomas. Since D2-40 and podoplanin appear to be highly sensitive and specific for epithelioid mesotheliomas, either may be considered for inclusion in the battery of antibodies currently recommended for distinguishing epithelioid mesotheliomas from metastatic carcinomas. However, it should be kept in mind that their utility has not yet been fully determined in routine diagnostic work.

The t(14;18) in Diffuse Large B-Cell Lymphoma

The clinical and biologic relevance of the t(14;18) and features of germinal center (GC) differentiation in diffuse large B-cell lymphoma (DLBCL) remain controversial. The authors examined the association of t(14;18) with GC-associated markers and clinical features in 44 de novo DLBCLs (22 nodal and 22 primary extranodal). CD10, bcl-2, and bcl-6 were expressed in 50%, 62%, and 54% of cases respectively. There were no significant differences in expression of these markers between nodal and extranodal cases. Coexpression of CD10 and bcl-6 was seen in 12 of 41 cases, and was more frequent in nodal than extranodal DLBCL (9 of 21 vs. 3 of 20; P = 0.05). A CD10+/bcl-6+ phenotype was not significantly associated with bcl-2 expression, stage, complete remission rate, or survival. The t(14;18) was found in 7 of 44 (16%) cases (6 nodal, 1 extranodal; P = 0.09). It was associated with a CD10+/bcl-6+ phenotype (5 of 7 vs. 7 of 27; P = 0.015) and a trend toward more frequent bcl-6 expression (6 of 7 vs. 15 of 34; P = 0.09), but no association with bcl-2 expression, CD10, clinical stage, complete remission, or survival. Among nodal or high-stage (III-IV) DLBCL, cases with the t(14;18) showed a trend toward decreased survival (P = 0.12).

Immunoreactivity of CD10 and inhibin alpha in differentiating hemangioblastoma of central nervous system from metastatic clear cell renal cell carcinoma

The differential diagnosis between hemangioblastoma of the central nervous system and metastatic clear cell renal cell carcinoma can be problematic, because they may share striking morphologic similarities. Since CD10 is expressed in clear cell renal cell carcinoma, while inhibin alpha is expressed in hemangioblastoma, we used CD10 and inhibin alpha (inhibin A) to study their possible use in the distinction of these two entities. A total of 22 cases of cerebellar hemangioblastoma, five cases of metastatic clear cell renal cell carcinoma to the central nervous system, and 16 primary cases of clear cell renal cell carcinoma were studied with immunohistochemical staining of both CD10 and inhibin A. All 22 cases of hemangioblastoma were immunonegative for CD10 in the stromal cells. In contrast, all five cases of metastatic clear cell renal cell carcinoma and 16 cases of primary clear cell renal cell carcinoma showed positive CD10 membranous staining. In all, 20 cases of hemangioblastoma (20/22, 91%) expressed inhibin A in the stromal cells. Two cases of primary clear cell renal cell carcinoma (2/16, 13%) and three cases of metastatic clear cell renal cell carcinoma (3/5, 60%) showed immunopositivity for inhibin A. In conclusion, in addition to the immunostaining of inhibin A, CD10 is a superior marker for distinguishing between a hemangioblastoma and a metastatic clear cell renal cell carcinoma.

PU.1 protein expression has a positive linear association with protein expression of germinal centre B cell genes includingBCL-6, CD10, CD20 andCD22: identification of PU.1 putative binding sites in theBCL-6 promotor

The transcription factor PU.1 has been shown to be crucial for the early stages of B cell development but its function at later stages of B cell development is less well known. We observed previously that PU.1 is expressed uniformly throughout the mature pre-plasma cell B cell population, the only exception being a subpopulation of germinal centre (GC) cells which showed exceptionally high expression of PU.1. This suggested that PU.1 may also have a role in GC B cell biology. To test this hypothesis and to screen for possible genes regulated by PU.1, we first evaluated semi-quantitatively the possible co-expression of PU.1 with proteins known to be upregulated or downregulated during GC B cell development. Normal lymphoid tissues and 255 B cell non-Hodgkin lymphomas of putative GC B cell origin were evaluated. PU.1 expression was positively associated with CD10 (p < 0.0001), CD20 (p = 0.043), CD22 (p = 0.005), CD79a (p = 0.024) and Bcl-6 (p < 0.0001) and negatively associated with cytoplasmic immunoglobulin light-chain expression (p = 0.036) in diffuse large B cell lymphoma. Identical or nearly identical associations were found in follicular lymphoma. Since CD20 is known to be partly regulated by PU.1 and putative PU.1-binding sites have been described in the regulatory regions of the CD22, CD79a and CD10 genes, we looked for putative PU.1 binding sites in the BCL6 promotor. Four such putative PU.1 binding sites were identified. Further analysis by gel-shift electromobility essay showed that PU.1 protein binds to three of the four putative binding sites in the BCL6 promotor. PU.1 and Bcl-6 were also found to be upregulated in centroblasts in the normal GC, but jointly downregulated in a subpopulation of centrocytes. Our findings support the contention that PU.1 may also have an important role in GC B cell development.

CD10 is a diagnostic and prognostic marker in renal malignancies

AIMS

To determine the diagnostic and prognostic value of CD10 immunoreactivity in renal cell carcinomas (RCCs) and transitional cell carcinomas (TCCs).

METHODS AND RESULTS

CD10 expression was investigated in primary (n = 180) and metastatic (n = 58) RCCs and upper urinary tract TCCs (n = 53) using a tissue microarray technique. One hundred and fifty-four of 172 (90%) evaluable primary and 48/56 (86%) evaluable metastatic RCCs expressed CD10. Extensive immunoreactivity (positivity of >50% cancer cells) decreased with rising tumour grade in conventional RCCs [G1/G2 72/81 (89%), G3/G4 33/48 (69%); P = 0.009]. Chromophobe RCCs showed a significantly lower overall and extensive immunoreactivity compared with conventional tumours (P < 0.001). In papillary RCCs immunoreactivity of more than 10% of cancer cells for CD10 was seen more often in type 2 (7/8, 88%) compared with type 1 (5/12, 42%; P =0.054) tumours. In conventional RCCs, pure apical membranous staining was associated with low tumour stage (P = 0.003), low grade (P = 0.004) and improved prognosis on univariate analysis (P = 0.031). TCCs were less frequently stained (51%). Extensive staining, however, was associated with high-stage tumours (P = 0.024), high-grade (P = 0.073) tumours, and was associated with shorter disease-free survival in univariate analysis (P = 0.003).

CONCLUSIONS

CD10 proved to be an additional marker for renal malignancies with predominantly diagnostic potential.

CD10 expression in the female genital tract: does it have useful diagnostic applications?

In the female genital tract, CD10 was initially found to be expressed in endometrial stromal tumors of the uterus as well as in mesonephric remnants and related lesions and was thought to be helpful in distinguishing these tumors from their mimics. However, new studies have shown CD10 to be expressed in a wide range of tumors of the female genital tract, making this antibody of limited diagnostic value. This review discusses diagnostic applications of CD10 in the female genital tract, with emphasis on CD10 use in mesenchymal tumors of the uterus and in the differential diagnosis of mesonephric versus non-mesonephric carcinomas, where CD10 positivity alone may be misleading in the final classification of a tumor. CD10 may be useful in establishing the diagnosis of endometriosis (with the exception of the cervix), distinguishing metastatic renal clear cell carcinoma from a primary ovarian clear cell carcinoma, and distinguishing mesonephric hyperplasia from other benign glandular proliferations of the cervix.

Angioimmunoblastic T-Cell Lymphoma With Cutaneous Involvement: A Case Report With Subtle Histologic Changes and Clonal T-Cell Proliferation

Angioimmunoblastic T-cell lymphoma is a nodal peripheral T-cell lymphoma that rarely involves the skin. We describe a 62-year-old Taiwanese man who developed a second relapse of angioimmunoblastic T-cell lymphoma with generalized erythroderma and numerous plaquelike and nodular lesions. Biopsy of the erythematous skin lesion demonstrated mild infiltrate of atypical small lymphocytes, some with clear cytoplasm. The lymphoid infiltrate was located mainly around skin appendages and in the upper dermis without epidermotropism. Immunohistochemically, these atypical lymphocytes expressed CD3. Polymerase chain reaction analysis for T-cell receptor γ-chain gene rearrangement using paraffin section showed the same-sized monoclonal bands in the skin and 2 previous nodal biopsies. We conclude that the histologic features of angioimmunoblastic T-cell lymphoma involving skin may be very subtle, showing only mild lymphoid infiltrate. Awareness of the history of angioimmunoblastic T-cell lymphoma with ancillary studies, including clonality testing for T-cell receptor gene rearrangement, is crucial for reaching an accurate diagnosis.

The diagnostic utility of immunohistochemistry in distinguishing between mesothelioma and renal cell carcinoma: A comparative study

Both mesotheliomas and renal cell carcinomas can present a wide variety of morphological patterns. Because of this, renal cell carcinomas that metastasize to the pleura and lung may be confused with mesotheliomas. The aim of the present study was to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and renal cell carcinoma. A total of 48 mesotheliomas (40 epithelioid, 8 sarcomatoid), and 48 renal cell carcinomas (24 conventional, 12 chromophobe, 8 papillary, 4 sarcomatoid) were investigated for the expression of the following markers: calretinin, mesothelin, cytokeratin 5/6, WT1, thrombomodulin (TM), N-cadherin, CD15 (leu-M1), MOC-31, Ber-EP4, BG-8 (Lewis(y)), CD10, renal cell carcinoma marker (RCC Ma), carcinoembryonic antigen (CEA), and B72.3. All (100%) of the epithelioid mesotheliomas reacted for calretinin, mesothelin, and cytokeratin 5/6; 93% for WT1; 78% for TM; 75% for N-cadherin, 48% for CD10, 15% for Ber-EP4, 8% for MOC-31, 8% for RCC Ma, 5% for BG-8, and none for CEA, B72.3, or CD15. Of the sarcomatoid mesotheliomas, 88% expressed calretinin, 75% N-cadherin, 38% CD10, and 13% each expressed cytokeratin 5/6, WT1, and TM. All of the remaining markers were negative. Among the RCCs, 81% expressed CD10, 75% N-cadherin, 63% CD15, 50% RCC Ma, 50% MOC-31, 42% Ber-EP4, 8% BG-8, and 2% TM. The remaining markers were negative. The results indicate that calretinin, mesothelin, and cytokeratin 5/6 are the best positive mesothelioma markers for differentiating epithelioid mesotheliomas from renal cell carcinomas. The best discriminators among the antibodies considered negative markers for mesothelioma are CD15, MOC-31, and RCC Ma. An accurate differential diagnosis can be reached with the use of any 2 of the 3 recommended positive markers, which should be selected based on availability and on which ones yield the best staining results in a given laboratory. One of the recommended negative markers may be added to the panel if deemed necessary. If confirmation of renal origin is needed, RCC Ma could be useful. Calretinin is the only marker that appears to have any utility in distinguishing between sarcomatoid mesotheliomas and sarcomatoid renal cell carcinomas.

Benign CD10-Positive T Cells in Reactive Lymphoid Proliferations and B-Cell Lymphomas

Recent reports have indicated that the neoplastic T cells of angioimmunoblastic T-cell lymphoma express CD10. It has been suggested that the demonstration of a CD10+ T-cell population may assist in establishing a diagnosis of angioimmunoblastic T-cell lymphoma and in distinguishing angioimmunoblastic T-cell lymphoma from other peripheral T-cell lymphomas. It has been unclear, however, whether this phenotypically unusual T-cell population might be present in other settings as well. In this report, we have retrospectively examined 64 cases of lymph node and solid tissue biopsies for the presence of CD10+ T cells using multicolor flow cytometry. Discrete populations of CD10+ T cells were found in 5 of 28 cases (18%) of reactive lymphoid hyperplasia, 4 of 17 cases (23%) of follicular lymphoma, and 9 of 19 cases (47%) of marginal zone B-cell lymphomas. The CD10+ T cells constituted 1-6% of total cells analyzed and </=14% of the total T-cell population. Using two-color immunohistochemical stains, many of the CD10+ PAX5-negative presumptive T cells were found to be located within germinal centers. These findings indicate that a normal small subset of CD10+ peripheral T cells exists and, at least when present in small numbers, should not be considered an indication of a T-cell neoplasm.

CD10 is helpful in detecting occult or inconspicuous endometrial stromal cells in cases of presumptive endometriosis

BACKGROUND

Previous studies have shown that CD10 is a marker for normal, ectopic, and neoplastic endometrial stromal cells. However, its value in confirming a diagnosis of presumptive endometriosis has not been extensively studied.

OBJECTIVE

To assess the reactivity of CD10 in a series of cases of presumptive endometriosis and to establish the potential usefulness of this antibody in confirming the diagnosis.

DESIGN

We studied hematoxylin-eosin sections and immunoreactivity of CD10 in 20 cases diagnosed as "suspicious for," "suggestive of," or "compatible with" endometriosis as well as in 12 cases of lesions that may be confused with endometriosis (3 endosalpingioses, 3 mesothelial hyperplasias, 3 ovarian follicular cysts, and 3 hemorrhagic corpora lutea).

RESULTS

Routine sections from cases of presumptive endometriosis showed glands lacking a distinct cuff of endometrial stromal cells because of atrophy or because of changes secondary to hemorrhage, inflammation, fibrosis, and/or cystic dilatation. In a few cases, the distinction between endometrial and ovarian stroma could not be assessed with certainty. CD10 immunostaining confirmed the diagnosis in 17 (85%) of the cases, as it strongly stained endometrial stromal cells that were not apparent on hematoxylin-eosin sections. All sections from lesions that may simulate endometriosis were CD10-.

CONCLUSION

CD10 is helpful in detecting occult or inconspicuous ectopic endometrial stromal cells and in distinguishing endometriosis from its potential mimickers. We recommend its use to confirm or exclude the presence of endometrial stromal cells in cases of presumptive endometriosis and in lesions that may be mistaken for this entity.

A panel of immunohistochemical stains assists in the distinction between ovarian and renal clear cell carcinoma

The diagnosis of primary clear cell carcinoma of the ovary or kidney is usually straightforward. However, problems in ascertaining the site of the primary tumor may arise when there is widespread metastatic disease or when clear cell carcinoma is present in both the ovary and kidney. In this study, the value of a panel of antibodies in distinguishing between an ovarian and renal clear cell carcinoma was evaluated. The panel comprised cytokeratin (CK)7 and 20, vimentin, estrogen receptor (ER), CD10, and renal cell carcinoma (RCC) marker. Ovarian clear cell carcinomas (n=14) were positive with CK7 (14/14), vimentin (6/14), ER (2/14), and RCC marker (2/14). All were negative with CD10 and CK20. Renal clear cell carcinomas (n=14) were positive with CD10 (14/14), RCC marker (14/14), vimentin (7/14), CK7 (2/14), and CK20 (1/14). All were negative with ER. This panel allows clear cell carcinomas of the ovary and kidney to be distinguished with a high degree of certainty and is a useful adjunct to histologic examination. Primary ovarian clear cell carcinomas are characterized by CK7 positivity, whereas primary renal neoplasms are characterized by positivity for CD10 and RCC marker and negative staining with CK7.

Critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the stomach and small intestine

Diffuse large B-cell lymphoma (DLBCL) of the gastrointestinal tract is heterogeneous, including mucosa-associated lymphoid tissue (MALT) origin and non-MALT, and they are indistinguishable. MALT lymphoma is a tumor of a post-germinal center (GC) memory B-cell origin, which is negative for Bcl-6 protein expression in low-grade but may become positive in high-grade tumors. Because Bcl-6 expression patterns in lymphoma of GC and non-GC B-cell origins have recently been characterized and CD10 is generally regarded as a specific marker for GC B cells, we critically evaluated gastric and small intestinal DLBCLs to see whether it is possible to identify tumor of GC B-cell origin by immunostaining in archival specimens. High-grade MALT lymphoma (H-ML) of the stomach (n = 20) was defined by the presence of a concomitant lymphoepithelial lesion and/or follicular colonization; and DLBCLs de novo, both gastric (n = 31) and intestinal (n = 21), were defined by the absence of the above features. Immunostaining for Bcl-6 and CD10 was done using formalin-fixed, paraffin-embedded sections and was examined independently by three pathologists. Staining for Bcl-6 was positive (>10% of tumor cells) in 55 of 72 cases. However, two distinct patterns were recognized among those positive: diffusely dense (>75%) and sporadic (<75%). The former was further characterized by a consistency of Bcl-6+ tumor cell density at any given area, resembling the staining pattern of the GC or follicular lymphoma (FL) (GC/FL pattern), whereas the latter was, besides less dense population, by variable density from area to area. The GC/FL pattern was observed in 36% and 38% of gastric and intestinal DLBCLs de novo, respectively, but in none of the gastric H-ML. CD10 was positive in 12 of 71 cases (17%), all coexpressing Bcl-6. CD10+ tumors were more frequent in the intestinal (33%) than in gastric DLBCLs ( approximately 15%). Significantly, CD10 expression was observed in three gastric H-MLs, including one that displayed a distinct lymphoepithelial lesion.

IN CONCLUSION

1). tumors showing a diffusely dense pattern of Bcl-6 expression should be distinguished from those showing a sporadic pattern; for the former most likely represents the tumor of GC B-cell derivation, and the latter non-GC, including MALT lymphoma; 2). tumor of GC B-cell origin thus defined accounted for about one third of gastric as well as intestinal DLBCLs de novo but none of the gastric H-ML; and 3). CD10 expression can be seen in MALT lymphomas and should not be used as the marker for GC B cells.

Detection of germinal center B-cell lymphoma in archival specimens: critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the tonsil

Expression of Bcl-6 and CD10, markers for the tumor of the germinal center (GC) B-cell derivation, has been studied in primary diffuse large B-cell lymphomas (DLBCLs) of the lymph node, gastrointestinal tract, and mediastinum. In these studies, the coexpression rate of CD10 and Bcl-6 was relatively constant at 30% approximately 40%, but the frequency of Bcl-6+ tumors varied from 55% to 100%, raising doubts about the usefulness of Bcl-6 expression in identifying the tumor of GC B-cell derivation. Because the expression of Bcl-6 in tumors of non-GC B-cell origin has recently been reported, we critically evaluated the expression of Bcl-6 and CD10 in primary DLBCLs of the tonsil, a relatively common tumor in Japan and Korea. The cases (n = 51) represented a consecutive series for any recent 2-year period at several teaching hospitals in Korea and Japan. Formalin-fixed, paraffin-embedded specimens were used for immunostaining. Staining for Bcl-6 and CD10 was positive in 44 (86%) and 22 cases (45%), respectively. However, among those positive for Bcl-6 (>10% Bcl-6+ tumor cells), 2 basic patterns were recognized: uniform and nonuniform. The uniform pattern was characterized by a dense population (>75%) and a consistent density in any given area, resembling the staining pattern observed in GC or follicular lymphoma (FL) (the "GC/FL" pattern). In contrast, the nonuniform pattern exhibited a varying density from area to area, as well as a less-dense population (<75%). The uniform pattern was observed in 26 cases (51%). All but 1 (95%) of the CD10+ tumors coexpressed Bcl-6, with most (82%) displaying the uniform pattern. We conclude that tumors showing a uniform pattern of Bcl-6 expression should be distinguished from those showing a nonuniform pattern, because the former most likely represent tumors of GC B-cell derivation and the latter most likely represent tumors of non-GC derivation. GC B-cell lymphoma thus defined accounted for 51% of tonsillar DLBCL, a proportion comparable to that of the nodal DLBCL. CD10 expression correlated with the "GC/FL" pattern, but appeared to be not essential for the identification of GC B-cell lymphoma. This study suggests that a significant proportion of tonsillar DLBCLs in Asia is of GC B-cell origin rather than of mucosa-associated lymphoid tissue origin. This finding may have significance for clinical management of these lymphomas.

Increased expression of the bcl6 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas

There is increasing evidence that bcl6 and CD10 expression may be related to apoptosis and cell cycle progression. Therefore, 79 cases of de novo diffuse large B-cell lymphomas were studied for the expression of bcl6 and CD10 proteins in relation to 1) the apoptotic index; 2) the proliferation-associated proteins Ki67, cyclin A, and cyclin B1; and 3) the expression of the bcl2, p53, Rb, p16, and p27 proteins. Expression of bcl6, CD10, and bcl2 proteins was found in 54/79 (68%), 28/79 (35%), and 47/74 (63%) cases, respectively. The bcl6/CD10 patterns were as follows: bcl6+/CD10+ (26 cases, 32%), bcl6+/CD10- (28 cases, 33%), bcl6-/CD10- (23 cases, 31%), and bcl6-/CD10+ (2 cases, 4%). Significant positive correlations were found between bcl6/Ki67 (r =.328, P =.003), bcl6/cyclin A (r =.265, P =.018), bcl6/apoptotic index (r =.327, P =.010), CD10/Ki67 (r =.296, P =.008), and CD10/apoptotic index (r =.397, P =.001). In addition, high expression of bcl6 showed significant correlation with negative (null/low) bcl2 expression (chi(2) test, P =.002). The above findings indicate that increased expression of the bcl6 and CD10 proteins is associated with increased apoptosis and proliferation in diffuse large B-cell lymphomas. The association between increased bcl6 expression and enhanced apoptosis might be due, at least in part, to the null/low bcl2 expression because previous in vitro data showed that bcl6 overexpression induces apoptosis accompanied by bcl2 and bcl-xl downregulation. Moreover, significant correlation was found between increased apoptotic index and the bcl6+/CD10+ pattern (t test: P =.014, Mann-Whitney test: P =.046). This finding and the positive correlation of the apoptotic index with bcl6 and CD10 expression may be related to previous results showing that the expression of these proteins has favorable effects on the clinical outcome of diffuse large B-cell lymphomas.

CD10 expression in epithelial tissues and tumors of the gynecologic tract: a useful marker in the diagnosis of mesonephric, trophoblastic, and clear cell tumors

We tested 417 cases of formalin-fixed, paraffin-embedded normal or hyperplastic gynecologic tissues as well as neoplasms involving the gynecologic tract with a monoclonal antibody against CD10 (clone 56C6), with special emphasis on epithelial and epithelial-like structures and tumors. CD10 was always expressed in mesonephric remnants (mesonephric remnants of the uterine cervix, epoophoron, rete ovarii) and tumors (mesonephric adenocarcinoma of the uterine cervix, tumors of wolffian origin of the broad ligament and ovary). CD10 was also positive in the syncytiotrophoblast, cytotrophoblast, and intermediate trophoblast of normal gestations, partial and complete moles, choriocarcinoma, and placental site trophoblastic tumors. Finally, CD10 was positive in several metastatic neoplasms to the gynecologic tract (100% in metastatic renal clear cell and intestinal carcinomas and melanomas). In contrast, CD10 was almost invariably negative in müllerian epithelia of the female genital tract and in their corresponding tumors, with the exception of focal expression found in squamous epithelia and tumors with squamous differentiation. Thus, the expression of CD10 may be useful in the establishing the diagnosis of mesonephric and trophoblastic tumors and in the differential diagnosis between gynecologic clear cell carcinoma (always negative) and metastatic clear cell carcinoma of renal origin.

Clinicopathologic reassessment of non-mycosis fungoides primary cutaneous lymphomas during 17 years

BACKGROUND

New classification systems have recently been proposed for primary cutaneous lymphomas (PCLs). The aim of our study was to evaluate the applicability and significance of the new classification systems to the diagnosis and management of non-mycosis fungoides (non-MF) PCL.

METHODS

Immunohistochemical restaining, histological reclassification, and clinical follow-up of all new non-MF PCL cases during 17 consecutive years were performed. The histological reclassification was performed according to the Revised European-American Lymphoma (REAL) classification, except for lymphomatoid papulosis (Lyp), which was included as an indolent lymphoma, according to the European Organization for the Research and Treatment of Cancer (EORTC) classification.

RESULTS

During the period 1983-99, 251 new PCL cases were seen, 213 (85%) of which were MF and Sézary syndrome (eight cases), and 38 (15%) of which were non-MF. Of the latter, 20 (53%) were B-cell lymphomas, including eight (40%) follicle center lymphoma, follicular (FCLF), eight (40%) marginal zone lymphoma (MZL), two (10%) diffuse large cell lymphoma, and two (10%) unclassifiable cases. Most or all of the lesions did not stain for CD10, CD43, and bcl-2 protein, and immunostaining for kappa and lambda immunoglobulin light chain restriction was much more useful diagnostically in MZL. Of the 18 primary non-MF cutaneous T-cell lymphomas, 13 (72%) were Lyp, all of which were type A, four (22%) were CD30+ anaplastic large cell lymphoma, and one (6%) was natural killer (NK)/T-cell lymphoma. Except for the NK/T-cell lymphoma, all the other non-MF PCLs had an indolent course.

CONCLUSIONS

A minority of the routinely diagnosed PCLs are non-MF, equally divided between B- and T-cell lymphomas. The REAL classification is applicable to the majority, although it does not include entities such as Lyp; the clinical correlations are not as obvious because most of the non-MF PCLs tend to have a relatively indolent course.

Fuzzy neural network applied to gene expression profiling for predicting the prognosis of diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the largest category of aggressive lymphomas. Less than 50% of patients can be cured by combination chemotherapy. Microarray technologies have recently shown that the response to chemotherapy reflects the molecular heterogeneity in DLBCL. On the basis of published microarray data, we attempted to develop a long-overdue method for the precise and simple prediction of survival of DLBCL patients. We developed a fuzzy neural network (FNN) model to analyze gene expression profiling data for DLBCL. From data on 5857 genes, this model identified four genes (CD10, AA807551, AA805611 and IRF-4) that could be used to predict prognosis with 93% accuracy. FNNs are powerful tools for extracting significant biological markers affecting prognosis, and are applicable to various kinds of expression profiling data for any malignancy.

Application of tissue microarray technology to the study of non-Hodgkin's and Hodgkin's lymphoma

The immunohistochemical analysis of lymphoid neoplasms has led to refined classification schemes based on the profile of antigen expression and correlation with morphological, cytogenetic, molecular, and clinical features. Tissue microarrays (TMAs) are a powerful tool to rapidly characterize the phenotypic profile of a large number of samples. We show that this technique can be readily applied to the study of lymphoma by examining the expression profile of a series of 193 B-cell non-Hodgkin's lymphomas (NHLs) and 29 Hodgkin's lymphomas (HLs) using immunohistochemistry and in situ hybridization (ISH). The NHL cases were studied for the expression of commonly used markers-including CD3, CD5, CD10, CD20, CD23, CD30, CD43, Bcl-2, and cyclin D1 by immunohistochemical staining of TMAs-and these results were compared with whole sections (WS) of the same cases. We found a high degree of correlation between the results achieved with TMAs or WS (86% to 100% of cases). P53 and MIB-1 staining were studied, and the results were similar to that reported in the literature. HL cases were stained for CD20, CD30, CD15 (LeuM1), and latent membrane protein 1 expression, and ISH was performed using probes for EBER-1 and-2 transcripts. The results from HL cases on TMA sections matched exactly with those of WS. We correlated cytogenetic results with immunohistochemical stains and morphology in cases of mantle cell lymphoma [t(11;14)(q13;q32)] and follicular lymphoma [t(14;18)(q32;q24)]. This extensive expression profile of B-cell NHLs and HL tissues discloses the ability of TMAs to rapidly screen a large series of cases and represents the first report of method validation for this technique in the study of lymphoma.

CD10: a valuable tool for the light microscopic diagnosis of microvillous inclusion disease (familial microvillous atrophy)

Microvillous inclusion disease (MID) is a specific disorder of the intestinal brush border that leads to intractable secretory diarrhea in infants. At present, electron microscopic analysis is required for its definitive diagnosis. However, this technique is not always available or feasible, and the diagnostic microvillous inclusions may not be evident in all specimens. Accordingly, the availability of a panel of histochemical and immunohistochemical stains displaying a specific staining pattern for MID will allow pathologists to reach a definitive diagnosis of this disorder without recourse to electron microscopy. CD10 is a membrane-associated neutral peptidase, shown to have a linear brush-border staining pattern in normal small intestine. We studied the staining pattern of CD10 in small intestinal biopsies from six patients with MID and in 24 control cases (10 normal small intestine, 10 celiac disease, two autoimmune enteropathy, and two allergic enteropathy). All MID cases revealed prominent cytoplasmic CD10 immunoreactivity in surface enterocytes. In contrast, all control cases showed linear brush-border staining. Similar results were obtained with periodic acid-Schiff, polyclonal carcinoembryonic antigen, and alkaline phosphatase, three stains known to show cytoplasmic staining of surface enterocytes in MID. In conclusion, CD10 is a valuable tool for the diagnosis of MID. It may be used as part of a panel that includes other stains with a distinctive staining pattern in MID such as periodic acid-Schiff, polyclonal carcinoembryonic antigen, and alkaline phosphatase. We suggest that the definitive diagnosis of MID can be reached when small bowel biopsies from infants with intractable diarrhea display cytoplasmic staining of surface enterocytes with the above-mentioned stains.

Focal follicular features in tonsillar diffuse large B-cell lymphomas: follicular lymphoma with diffuse areas or follicular colonization

Focal follicular features in diffuse large B-cell lymphomas (DLBCLs) are bound to raise the question of follicular lymphoma (FL) with diffuse areas, because the diagnosis of FL is based on the presence of follicular areas, even though focal. We report 7 cases of primary tonsillar DLBCLs with focal follicular features that presented with morphologic, immunohistochemical, and biological features distinct from those of FL. Histologically, these tumors were characterized by involvement of pericryptal follicles with adjacent dominant diffuse areas. Monomorphous large tumor cells were evenly spaced with abundant, often clear cytoplasm, and blastoid nuclei often with a delicate nuclear membrane. Importantly, residual germinal centers (GCs) were present in the form of either an intrafollicular GC remnant or an isolated GC in the midst of diffuse tumor. An extrafollicular and/or parafollicular growth pattern was also observed. Bcl-6 staining revealed a predominantly sporadic occurrence of Bcl-6(+) cells, comprising <50% of tumor cells, and none displayed diffusely dense collections (>75%) of Bcl-6(+) tumor cells characteristic of the GC or FL. Staining for CD10 was negative in 6 cases. Five of 7 patients were younger than 60, the median age of other patients with primary tonsillar DLBCL. No extratonsillar involvement was seen at 18 months after diagnosis. After chemotherapy or radiotherapy, complete remission was achieved with ease in all patients, but 2 patients who were treated with chemotherapy alone relapsed at 24 and 30 months. In conclusion, tonsillar DLBCL includes a small (10%) but distinct subgroup that warrants distinction from FL with predominant diffuse areas or de novo DLBCL. It appears that the focal follicular features in tonsillar DLBCL likely represent follicular colonization of marginal zone B-cell lymphoma, probably high-grade, if the possibility of FL is excluded.

Comparison of multiparameter flow cytometry with cluster analysis and immunohistochemistry for the detection of CD10 in diffuse large B-Cell lymphomas

CD10 is a critical antigen for the distinction of follicle-center lymphoma from other B-cell lymphomas composed of small cells in fine-needle aspiration specimens, tissue core biopsies, and bone marrow. In addition, CD10 is expressed in a subset of diffuse large B-cell lymphomas (DLBCLs), where it may be an adverse prognostic indicator. We have previously demonstrated that CD10 expression detected by multiparameter flow cytometry (FC) with cluster analysis is highly sensitive and specific for follicle-center lymphoma in the differential diagnosis of small B-cell lymphomas. In this study, we assessed the utility of paraffin section immunohistochemistry (IHC) for CD10 compared with FC in a cohort of 50 DLBCLs. IHC for CD10 was technically successful in 47 of the 50 (94%) DLBCLs; 3 failed based on lack of internal CD10 reactivity. CD10 was expressed by FC in 20 of 47 DLBCLs (43%); CD10 was positive by IHC in 15 of these (75%). All 27 cases that were CD10(-) by FC were negative by IHC. The level of CD10 expression by FC in the 5 FC(+)/IHC(-) cases ranged from relatively dim to bright. Our results indicate 75% sensitivity and 100% specificity of CD10 expression by IHC compared with multiparameter FC with cluster analysis and a 6% technical failure rate.

Assessment of CD10 in the diagnosis of small B-cell lymphomas: a multiparameter flow cytometric study

We evaluated the usefulness of multiparameter flow cytometry with cluster analysis in the diagnosis of a series of 100 well-characterized small B-cell lymphomas (SBCLs). The histologic diagnoses in the 100 cases were follicular lymphoma (FL) in 58, marginal zone lymphoma (MZL) in 17, small lymphocytic lymphoma in 15, and mantle cell lymphoma (MCL) in 10. Of the 58 FLs, 57 were CD10 positive (98% sensitivity). The 1 negative case was unusual in that it occurred in the small intestine. However; architectural, cytologic, and immunohistochemicalfeatures were diagnostic of FL. Of 42 other SBCLs, 2 were CD10+ (95% specificity); 1 was a CD5+/cyclin D1 + MCL, and the other was an extranodal MZL. We found that assessment of CD10 expression using multiparameter flow cytometry with cluster analysis is highly sensitive and specific for the diagnosis of FL, validating its usefulness in situations in which adequate tissue is not available for definitive histologic diagnosis.

Immunohistochemical markers in the differentiation of thymic and pulmonary neoplasms

AIMS

The histopathological features of some thymic neoplasms overlap with those of pulmonary squamous and large-cell undifferentiated carcinomas, and identification of the primary site may be difficult on routine staining. We have assessed a panel of antibodies that may help to distinguish between neoplasms from these two sites.

METHODS AND RESULTS

Antibodies identifying cytokeratin 7 (CK7), CD5, CD10, CD1a and thyroid transcription factor-1 (TTF-1) were applied to a series of 20 thymic neoplasms (thymic carcinomas, atypical thymomas and thymomas), 10 primary squamous cell carcinomas of the lung and 10 large-cell undifferentiated carcinomas of the lung. Staining for TTF-1 was positive in 3/10 large-cell undifferentiated carcinomas, but negative in all other tumours. CD5 showed strong membranous staining in 3/6 thymic carcinomas and 1/14 thymomas, but only focal staining in 1/20 pulmonary carcinomas. CD1a was consistently positive in thymic lymphocytes in both typical and atypical thymomas, but only focally in 1/6 thymic carcinomas. CD1a stained dendritic cells in 7/20 pulmonary carcinomas, but did not stain lymphocytes. Staining for CK7 and CD10 did not aid in differentiating between a pulmonary or thymic origin of the tumour.

CONCLUSION

Staining for TTF-1, CD5 and CD1a have potential use in distinguishing between pulmonary and thymic neoplasms.

Neoplastic T cells in angioimmunoblastic T-cell lymphoma express CD10

Angioimmunoblastic T-cell lymphoma (AITL) is a systemic disease involving lymph nodes, spleen, and bone marrow. Although the histologic features have been well described, the diagnosis is often challenging, as there are no specific phenotypic or molecular markers available. This study shows that the neoplastic cells of AITL can be identified by aberrant CD10 expression. Archival material from 30 cases of AITL, 10 cases of peripheral T-cell lymphoma unspecified (PTL), and 10 cases of reactive lymphoid hyperplasia were reviewed. Single and double immunostaining for CD3, CD4, CD8, CD20, CD21, CD10, BCL6, Ki67, and LMP-1 in situ hybridization for Epstein-Barr early region and polymerase chain reaction (PCR) for T-cell receptor gamma chain gene and immunoglobulin heavy chain gene were performed. Three overlapping histologic patterns with hyperplastic follicles, depleted follicles, or without follicles were identified in AITL. Of the 30 cases of AITL, 27 contained CD10(+) T cells. No CD10(+) T cells were present in the cases of PTL or reactive hyperplasia. PCR confirmed a monoclonal or oligoclonal T-cell population in 29 of 30 cases of AITL and a monoclonal B-cell population in 6 cases. Analysis of microdissected CD10(+) single cells showed that they belonged to the neoplastic clone. In conclusion CD10 is a phenotypic marker that specifically identifies the tumor cells in 90% of AITL, including the early cases. The presence of these cells distinguishes AITL from other PTLs. This finding provides an objective criterion for accurate and early diagnosis of AITL.

CD10 is a marker for normal and neoplastic endometrial stromal cells

Using the immunohistochemical technique, we investigated the expression of CD10 in normal female genital tissues, chorionic villi and decidua of early gestation, endometriotic lesions, and uterine mesenchymal tumors. The cytoplasm of normal endometrial stromal cells was consistently positive for CD10. During early gestation, decidualized endometrial stromal cells were negative or only focally positive for CD10, whereas nondecidualized stromal cells were diffusely positive. Syncytiotrophoblast was positive for CD10 on the apical surface, whereas chorionic mesenchymal cells were diffusely positive within the cytoplasm. Cytotrophoblast and intermediate trophoblast were negative for CD10. Groups of stromal cells surrounding cervical glands were often positive for CD10. Myometrium, endometrial and cervical glands, cervical squamous epithelia, and tubal epithelia and stroma exhibited no reactivity for CD10. In endometriosis and adenomyosis, ectopic endometrial stromal cells were usually positive for CD10. Endometrial stromal tumors, including undifferentiated uterine sarcomas, mostly showed diffuse immunoreactivity for CD10. Leiomyomas and leiomyosarcomas were negative or focally (< 5% of cells staining) positive (8/12 leiomyomas and 4/8 leiomyosarcomas) for CD10, except for 1 myxoid leiomyosarcoma that showed CD10 staining in the myxoid areas. These data suggest that diffuse CD10 staining is characteristic of normal and neoplastic endometrial stromal cells, unless they are decidualized.

Mesonephric adenocarcinoma of the uterine corpus: CD10 expression as evidence of mesonephric differentiation

Mesonephric (wolffian) neoplasms of the female genital tract are infrequent and found in sites where embryonic remnants of wolffian origin are usually detected, such as the uterine cervix, broad ligament, mesosalpinx, and ovary. Their diagnosis is difficult because of the absence of specific immunohistochemical markers for mesonephric derivatives. We present the first report of adenocarcinoma of mesonephric type arising as a purely myometrial mass without endometrial or cervical involvement in the uterine corpus of a 33-year-old woman. The tumor showed a combination of patterns, with retiform areas, ductal foci, and small tubules with eosinophilic secretion, which merged with solid sheets of cells with a sarcomatoid appearance. Immunohistochemically, neoplastic cells were diffusely positive for cytokeratin 7, epithelial membrane antigen, and CD15 and focally positive for BerEP4 and vimentin. A hitherto unreported feature was the positivity for CD10 in neoplastic cells, which was also present in a large number of control tissues obtained from male mesonephric derivatives and female mesonephric remnants and tumors. Furthermore, CD10 was negative in controls from müllerian epithelia of the female genital tract and in their corresponding tumors. Therefore, the expression of CD10 by mesonephric remnants may be useful in establishing the diagnosis of tumors with mesonephric differentiation.