Interobserver Variability of Ki-67 Measurement in Breast Cancer

BACKGROUND: As measurement of Ki-67 proliferation index is an important part of breast cancer diagnostics, we conducted a multicenter study to examine the degree of concordance in Ki-67 counting and to find factors that lead to its variability. METHODS: Thirty observers from thirty different institutions reviewed Ki-67-stained slides of 20 different breast cancers on whole sections and tissue microarray (TMA) by online system. Ten of the 20 breast cancers had hot spots of Ki-67 expression. Each observer scored Ki-67 in two different ways: direct counting (average vs. hot spot method) and categorical estimation. Intraclass correlation coefficient (ICC) of Ki-67 index was calculated for comparative analysis. RESULTS: For direct counting, ICC of TMA was slightly higher than that of whole sections using average method (0.895 vs 0.858). The ICC of tumors with hot spots was lower than that of tumors without (0.736 vs 0.874). In tumors with hot spots, observers took an additional counting from the hot spot; the ICC of whole sections using hot spot method was still lower than that of TMA (0.737 vs 0.895). In categorical estimation, Ki-67 index showed a wide distribution in some cases. Nevertheless, in tumors with hot spots, the range of distribution in Ki-67 categories was decreased with hot spot method and in TMA platform. CONCLUSIONS: Interobserver variability of Ki-67 index for direct counting and categorical estimation was relatively high. Tumors with hot spots showed greater interobserver variability as opposed to those without, and restricting the measurement area yielded lower interobserver variability.

Lymphangiogenesis in Breast Cancer Correlates with Matrix Stiffness on Shear-Wave Elastography

PURPOSE: To correlate tumor stiffness and lymphangiogenesis in breast cancer and to find its clinical implications. MATERIALS AND METHODS: A total of 140 breast cancer patients were evaluated. Tumor stiffness was quantitatively measured by shear-wave elastography in preoperative ultrasound examination, calculated as mean elasticity value (kPa). Slides of resected breast cancer specimens were reviewed for most fibrotic area associated with tumor. D2-40 immunohistochemical staining was applied for fibrotic areas to detect the lymphatic spaces. Microlymphatic density, tumor stiffness, and clinicopathologic data were analyzed. RESULTS: Higher elasticity value was associated with invasive size of tumor, microlymphatic density, histologic grade 3, absence of extensive intraductal component, presence of axillary lymph node metastasis, and Ki-67 labeling index (LI) in univariate regression analysis, and associated with Ki-67 LI and axillary lymph node metastasis in multivariate regression analysis. Microlymphatic density was associated histologic grade 3, mean elasticity value, and Ki-67 LI in univariate regression analysis. In multivariate regression analysis, microlymphatic density was correlated with mean elasticity value. CONCLUSION: In breast cancer, tumor stiffness correlates with lymphangiogenesis and poor prognostic factors.

Pathologic Evaluation of Breast Cancer after Neoadjuvant Therapy

Breast cancer, one of the most common cancers in women, has various treatment modalities. Neoadjuvant therapy (NAT) has been used in many clinical trials because it is easy to evaluate the treatment response to therapeutic agents in a short time period; consequently, NAT is currently a standard treatment modality for large-sized and locally advanced breast cancers, and its use in early-stage breast cancer is becoming more common. Thus, chances to encounter breast tissue from patients treated with NAT is increasing. However, systems for handling and evaluating such specimens have not been established. Several evaluation systems emphasize a multidisciplinary approach to increase the accuracy of breast cancer assessment. Thus, detailed and systematic evaluation of clinical, radiologic, and pathologic findings is important. In this review, we compare the major problems of each evaluation system and discuss important points for handling and evaluating NAT-treated breast specimens.

Current Issues and Clinical Evidence in Tumor-Infiltrating Lymphocytes in Breast Cancer

With the advance in personalized therapeutic strategies in patients with breast cancer, there is an increasing need for biomarker-guided therapy. Although the immunogenicity of breast cancer has not been strongly considered in research or practice, tumor-infiltrating lymphocytes (TILs) are emerging as biomarkers mediating tumor response to treatments. Earlier studies have provided evidence that the level of TILs has prognostic value and the potential for predictive value, particularly in triple-negative and human epidermal growth factor receptor 2-positive breast cancer. Moreover, the level of TILs has been associated with treatment outcome in patients undergoing neoadjuvant chemotherapy. To date, no standardized methodology for measuring TILs has been established. In this article, we review current issues and clinical evidence for the use of TILs in breast cancer.

Expression of Sarcosine Metabolism-Related Proteins in Invasive Lobular Carcinoma: Comparison to Invasive Ductal Carcinoma

PURPOSE: The aims of this study were to compare the expression of sarcosine metabolism-related proteins between invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) and to determine the implications of these results. MATERIALS AND METHODS: Tissue microarrays were constructed, containing 30 samples from normal breast tissue, 114 samples from patients with ILC, and 692 samples from patients with IDC. Immunohistochemical staining was performed to examine the expression of sarcosine metabolism-related proteins [glycine N-methyltransferase, sarcosine dehydrogenase, and l-pipecolic acid oxidase (PIPOX)]. RESULTS: The sarcosine metabolic phenotype differed between ILC and IDC (plow sarcosine type (30.4%)>high sarcosine type (5.0%)>intermediate type (2.9%). However, in ILC, the sarcosine metabolic phenotype was distributed as low sarcosine type (61.4%)>null type (32.5%)>intermediate type (5.3%)>high sarcosine type (0.9%). PIPOX showed higher expression in ILC than in IDC (p<0.001) and correlated with androgen receptor (AR) positivity (p=0.001) in ILC. CONCLUSION: Expression of sarcosine metabolism-related proteins differed between ILC and IDC. Low sarcosine type was the majority sarcosine metabolic phenotype of ILC. PIPOX expression was predominant in ILC and correlated with AR positivity.

The Role and Regulatory Mechanism of 14-3-3 Sigma in Human Breast Cancer / 한국유방암학회지

PURPOSE: 14-3-3 sigma (sigma) is considered to be an important tumor suppressor and decreased expression of the same has been reported in many malignant tumors by hypermethylation at its promoter or ubiquitin-mediated proteolysis by estrogen-responsive ring finger protein (Efp). In this study, we investigated the significance of 14-3-3 sigma expression in human breast cancer and its regulatory mechanism. METHODS: Efp was silenced using small interfering RNA (siRNA) in the MCF-7 breast cancer cell line in order to examine its influence on the level of 14-3-3 sigma protein. The methylation status of the 14-3-3 sigma promoter was also evaluated by methylation-specific polymerase chain reaction (PCR). The expression of Efp and 14-3-3 sigma in 220 human breast carcinoma tissues was assessed by immunohistochemistry. Other clinicopathological parameters were also evaluated. RESULTS: Silencing Efp in the MCF-7 breast cancer cell line resulted in increased expression of 14-3-3 sigma. The Efp-positive human breast cancers were more frequently 14-3-3 sigma-negative (60.5% vs. 39.5%). Hypermethylation of 14-3-3 sigma was common (64.9%) and had an inverse association with 14-3-3 sigma positivity (p=0.072). Positive 14-3-3 sigma expression was significantly correlated with poor prognosis: disease-free survival (p=0.008) and disease-specific survival (p=0.009). CONCLUSION: Our data suggests that in human breast cancer, the regulation of 14-3-3 sigma may involve two mechanisms: ubiquitin-mediated proteolysis by Efp and downregulation by hypermethylation. However, the inactivation of 14-3-3 sigma is probably achieved mainly by hypermethylation. Interestingly, 14-3-3 sigma turned out to be a very significant poor prognostic indicator, which is in contrast to its previously known function as a tumor suppressor, suggesting a different role of 14-3-3 sigma in breast cancer.

Positive Expression of Insulin-Like Growth Factor-1 Receptor Is Associated with a Positive Hormone Receptor Status and a Favorable Prognosis in Breast Cancer / 한국유방암학회지

PURPOSE: Insulin-like growth factor 1 receptor (IGF-1R) is commonly expressed in primary breast cancers. Understanding the role of IGF-1R signaling in the different subtypes of breast cancer is important because each subtype has a different outcome and requires different treatment modalities. However, the precise biological significance of IGF-1R expression in cancer cells is still unclear. In this study, we examined the expression of IGF-1R in the different molecular subtypes of breast cancer. The effects of IGF-1R expression on the survival rates and outcomes of breast cancer were also examined. METHODS: IGF-1R expression was evaluated immunohistochemically in tissue microarray blocks constructed from 1,198 invasive breast cancer samples collected from six medical institutions. IGF-1R expression was interpreted according to the human epidermal growth factor receptor 2 (HER2)/neu immunohistochemistry scoring system. Scores of 2+ and 3+ were considered positive. RESULTS: Positive IGF-1R expression was observed in 65.4% of invasive breast cancer samples. IGF-1R expression was detected in all cancer subtypes (luminal A, 84.4%; luminal B, 75.9%; HER2, 21.2%; triple-negative, 46.6%) and was found to be associated with a positive hormone receptor status and the absence of HER2 amplification (p<0.001). Positive IGF-1R expression was significantly associated with high survival rates (p=0.014). However, a multivariate analysis revealed that the expression levels of IGF-1R did not achieve statistical significance. In the triple-negative cancer subtype, IGF-1R expression was found to be associated with a lower disease-free survival rate (p=0.031). CONCLUSION: Positive IGF-1R expression is associated with a favorable prognosis in breast cancer. IGF-1R is frequently expressed in the luminal A/B subtypes of breast cancer, and its expression is related to the hormone receptor status.

Expression of Glycolysis-Related Proteins in Solid Papillary Carcinoma of the Breast According to Basement Membrane Status

PURPOSE: The aim of this study was to investigate the differences of expression in glycolysis-related proteins such as Glut-1, carbonic anhydrase (CA) IX, and monocarboxylate transporter (MCT) 4 according to the myoepithelial cell (MEC) and basement membrane (BM) status in solid papillary carcinoma (SPC) of the breast. MATERIALS AND METHODS: Immunohistochemical evaluation of Glut-1, CAIX, and MCT4, as well as p63 and type IV collagen, were performed on 23 SPC cases. RESULTS: Six and nine cases of SPC showed the presence and absence of myoepithelial cells, respectively, and eight cases belonged to the borderline status (p63-positive MEC on some areas of the outer tumor surface but not in others). BM was partially or completely absent in 14 cases and present in nine cases. SPC lacking BM more frequently showed high expression of CAIX than SPC with BM (p=0.037). CONCLUSION: In SPC of the breast, a strong expression of CAIX seems to be associated with an increasing degree of loss of BM, which can be interpreted as BM degradation due to the induction of extracellular acidity with increasing expression of CAIX.

The Expression of Glut-1, CAIX, and MCT4 in Mucinous Carcinoma / 한국유방암학회지

PURPOSE: The aim of this study was to assess the expression of metabolism-related proteins including glucose transporter 1 (Glut-1), carbonic anhydrase IX (CAIX) and monocarboxylate transporter 4 (MCT4) in breast mucinous carcinoma and to evaluate the implications of the results. METHODS: Immunohistochemical staining for Glut-1, CAIX, and MCT4 was performed on tissue sections from 59 cases of mucinous carcinoma to evaluate the association between the expression of metabolism-related proteins and clinicopathologic factors. Mucinous carcinoma was subclassified into type A and type B according to histopathological characteristics. RESULTS: Of the 59 patients, 35 patients (59.3%) were type A mucinous carcinoma and 24 patients (40.7%) were type B mucinous carcinoma. Stromal expression of MCT4 was significantly associated with a high histologic grade (p=0.022) and type B mucinous carcinoma (p=0.016). There were significant positive correlations between the expression of Glut-1, CAIX and tumoral expression of MCT4 (p<0.05). CONCLUSION: We assessed the expression of metabolism-related proteins including Glut-1, CAIX, and MCT4 in breast mucinous carcinoma and found that the stromal expression of MCT4 was higher in type B mucinous carcinoma than in type A, which reflected a difference in the tumor microenvironment.

Primary Mucinous Cystadenocarcinoma of the Breast: Cytologic Finding and Expression of MUC5 Are Different from Mucinous Carcinoma

Mucinous cystadenocarcinoma (MCA) in the breast is a rare neoplasm. There have been 13 cases of primary breast MCA reported. The MCA presents as a large, partially cystic mass in postmenopausal woman with a good prognosis. The microscopic findings resemble those of ovarian, pancreatic, or appendiceal MCA. The aspiration findings showed mucin-containing cell clusters in the background of mucin and necrotic material. The cell clusters had intracytoplasmic mucin displacing atypical nuclei to the periphery. Histologically, the tumor revealed an abundant mucin pool with small floating clusters of mucin-containing tumor cells. There were also small cysts lined by a single layer of tall columnar mucinous cells, resembling those of the uterine endocervix. The cancer cells were positive for mucin (MUC) 5 and negative for MUC2 and MUC6. This mucin profile is different from ordinary mucinous carcinoma and may be a unique characteristic of breast MCA.

The Clinicopathologic Features of Molecular Apocrine Breast Cancer

BACKGROUND: To elucidate the clinicopathologic features and their implications on the immunohistochemistry in cases of molecular apocrine breast cancer (MABC). METHODS: Immunohistochemical (IHC) staining for estrogen receptor (ER), human epidermal growth factor receptor 2 (HER-2), cytokeratin (CK) 5/6, epidermal growth factor receptor (EGFR), androgen receptor (AR), gamma-glutamyltrasferase 1 (GGT1) and Ki-67 was performed on tissue microarray breast cancer samples from 204 patients. Phenotypes of breast cancer were divided based on the IHC status of ER, AR and GGT1 into the following: luminal type, ER positive and AR and/or GGT1 positive; basal type, ER, AR, and GGT1 negative; non-basal type, ER positive and AR and GGT1 negative; and MABC type, ER negative and AR and/or GGT1 positive. RESULTS: In our series of patients (n=204), there were 26 cases of MABC. Besides, there were 18, 60, and 100 cases of luminal type, basal type and non-basal type, respectively. The MABC demonstrated apocrine histology and a higher prevalence of HER-2 positivity than other phenotypes. With the basal type, the MABC manifested a more frequent expression of CK5/6 and EGFR and a higher Ki-67 index than other phenotypes (p<0.001). There were no significant differences in patient prognosis between the phenotypes of breast cancer. CONCLUSIONS: MABC are distinguishable from other phenotypes based on the apocrine histology and a higher expression rate of HER-2.

Immunophenotypes of Glycogen Rich Clear Cell Carcinoma

PURPOSE: Glycogen rich clear cell carcinoma (GRCC) of the breast is a rare subtype of invasive ductal carcinoma and involves a poor prognosis. In the literature, less than 150 cases have been reported. Many researchers have attempted to characterize GRCC according to electron microscope, flow cytometry, or clinical data. However, an organized study of the immunophenotype of GRCC has yet to be reported. MATERIALS AND METHODS: Here, we present three cases of GRCC and their immunohistochemical profiles. RESULTS: Histologically, all three cases contained periodic acid stain (PAS) positive and d-PAS labile granules in their clear cytoplasm. Case I showed positivity for only estrogen receptor (ER) and c-erbB2. Case II exhibited positivity for progesterone receptor and negativity for ER and c-erbB2. Case III presented with triple negative invasive carcinoma. The expression pattern of E-cadherin was concordant with epidermal growth factor receptor and c-kit, but discordant with ki-67. Among these three cases, p53-positive cases exhibited a low proliferative index (ki-67: 15%), while p53-negative cases showed a high proliferative index (ki-67: 50-60%). CONCLUSION: In conclusion, the immunophenotype of GRCC is not uniform, but is similar to that of conventional ductal carcinoma.

Proposal for Creating a Guideline for Cancer Registration of Microinvasive Tumors of the Breast and Ovary (II)

BACKGROUND: Cancer registration in Korea has a longer than 30-years of history, during which time cancer registration has improved and become well-organized. Cancer registries are fundamental for cancer control and multi-center collaborative research. However, there have been discrepancies in assigning behavior codes. Thus, we intend to propose appropriate behavior codes for the International Classification of Disease Oncology, 3rd edition (ICD-O-3) for microinvasive tumors of the ovary and breast not only to improve the quality of the cancer registry but also to prevent conflicts. METHODS: As in series I, two pathology study groups and the Cancer Registration Committee of the Korean Society of Pathologists (KSP) participated. To prepare a questionnaire on provisional behavior code, the relevant subjects were discussed in the workshop, and consensus was obtained by convergence of opinion from members of KSP. RESULTS: Microinvasive tumor of the breast should be designated as a microinvasive carcinoma which was proposed as malignant tumor (/3). Serous borderline tumor with microinvasion of the ovary was proposed as borderline tumor (/1), and mucinous borderline tumor with microinvasion of the ovary as either borderline (/1) or carcinoma (/3) according to the tumor cell nature. CONCLUSIONS: Some issues should be elucidated with the accumulation of more experience and knowledge. Here, however, we present our second proposal.

Proposal for Creating a Guideline for Cancer Registration of Microinvasive Tumors of the Breast and Ovary (II)

BACKGROUND: Cancer registration in Korea has a longer than 30-years of history, during which time cancer registration has improved and become well-organized. Cancer registries are fundamental for cancer control and multi-center collaborative research. However, there have been discrepancies in assigning behavior codes. Thus, we intend to propose appropriate behavior codes for the International Classification of Disease Oncology, 3rd edition (ICD-O-3) for microinvasive tumors of the ovary and breast not only to improve the quality of the cancer registry but also to prevent conflicts. METHODS: As in series I, two pathology study groups and the Cancer Registration Committee of the Korean Society of Pathologists (KSP) participated. To prepare a questionnaire on provisional behavior code, the relevant subjects were discussed in the workshop, and consensus was obtained by convergence of opinion from members of KSP. RESULTS: Microinvasive tumor of the breast should be designated as a microinvasive carcinoma which was proposed as malignant tumor (/3). Serous borderline tumor with microinvasion of the ovary was proposed as borderline tumor (/1), and mucinous borderline tumor with microinvasion of the ovary as either borderline (/1) or carcinoma (/3) according to the tumor cell nature. CONCLUSIONS: Some issues should be elucidated with the accumulation of more experience and knowledge. Here, however, we present our second proposal.

HER2 Status by Standardized Immunohistochemistry and Silver-Enhanced In Situ Hybridization in Korean Breast Cancer / 한국유방암학회지

PURPOSE: Amplification of the human epidermal growth factor receptor 2 (HER2) gene occurs in 18% to 20% of breast cancers, and it is recognized as a prognostic and predictive marker. We investigated the HER2 status in Korean breast cancer by immunohistochemistry (IHC) and silver-enhanced in situ hybridization (SISH), as the first step toward building a nationwide quality assurance program for HER2 testing. METHODS: A total of 1,198 breast carcinoma samples were collected from six institutions and IHC and SISH were performed using tissue microarrays in central laboratories. The results were compared to those of local laboratories. RESULTS: Available data were obtained from 959 samples. Central IHC results were negative, equivocal, and positive for 756 (78.8%; range among institutions, 76.8-81.8%), 37 (3.9%; 1.9-6.2%), and 166 (17.3%; 13.6-20%), respectively. SISH results were negative, equivocal, and positive for 756 (78.8%; 77.4-79.9%), 2 (0.2%; 0-0.7%), and 201 (21%; 20.1-22.2%), respectively. HER2 gene amplification was observed in 4.4%, 19%, and 73.9% of the negative, equivocal and positive groups stratified by local IHC results, respectively. When central SISH was considered to be the gold standard method for measuring HER2 status, the false-negative and false-positive rates of local IHC were 14.4% (29/201) and 7.1% (54/756). The concordance rate between central IHC and SISH was 98.4%. CONCLUSION: Central IHC and SISH markedly decreased the interlaboratory variability of HER2 status and the results of the two were highly concordant. The quality control program for HER2 testing must be focused on decreasing both the false negativity and positivity of IHC in local laboratories.

Correlation of Early Systemic Recurrence with In Vitro Adenosine Triphosphate-Based Chemotherapy Response Assay in Stage II and III Breast Cancer Patients Treated with Doxorubicin-Based Chemotherapy / 한국유방암학회지

PURPOSE: An in vitro adenosine triphosphate-based chemotherapy response assay (ATP-CRA) was designed to require only a limited number of cells and shorten test turnaround time with a high success rate. This study investigated the correlation between in vitro doxorubicin sensitivity of tumor cells and early systemic recurrence, defined as recurrence within 2 years after surgery. METHODS: From January 2004 to March 2007, the ATP-CRA for doxorubicin was tested in 128 patients among breast cancer patients treated at Gangnam Severance Hospital, Seoul, Korea. The American Joint Committee on Cancer stages for all patients were II and III. All patients received doxorubicin-based chemotherapy. Selected patients were divided into a chemosensitive group and a non-chemosensitive group, according to a 40% cell death rate as a cut-off value. We analyzed the relationship between chemosensitivity and early systemic recurrence in patients with breast cancer. RESULTS: The mean age of the patients investigated was 44.6-years-old, the mean follow-up period was 39.9 months, and recurrence free survival was 38.6 months. Thirteen recurrences were observed during follow-up. Among 13 patients with a recurrence, eight had a recurrence within 2 years (early recurrence). All of the early recurring patients belonged to the non-sensitive group. Doxorubicin sensitivity results measured by ATP-CRA were related with early recurrence free survival in patients with breast cancer (p=0.030). The mean cell death rate derived from the ATP-CRA for the early recurrence group tended to be lower than that of the non-early recurrence group, but the difference was not statistically significant (p=0.05). CONCLUSION: Doxorubicin sensitivity measured by ATP-CRA was well correlated with in vivo drug responsibility to predict early recurrence against doxorubicin-based adjuvant chemotherapy in patients with breast cancer.

A Multi-institutional Study of Interlaboratory Variance in the Estrogen and Progesterone Receptor Assays / 한국유방암학회지

PURPOSE: The expression of hormone receptors is the most reliable factor for predicting the responsiveness to hormonal therapy. At present, immunohistochemistry (IHC) is considered as a practically reliable method. This study was designed to examine the interlaboratory variance in immunohistochemical assays for estrogen receptor (ER) and progesterone receptor (PR) in Korea. METHODS: The Korean Study Group for Breast Pathology (KSGBP) made a questionnaire to know the current situation in HR assay in Korea. The questionnaire was sent to the members of KSGBP by e-mail, which were included eight questions relating to tissue handling, ER/PR IHC procedure and interpretation method. Forty laboratories replied with the completed questionnaire. RESULTS: All 40 laboratories were using formalin as a fixative. Pretreatment was performed using six different methods including autoclave (25%), microwave (30%) and full autostainer (15%). Primary antibodies for ER were SP1 in 40%, 6F11 in 27.5% and 1D5 in 32.5%. Primary antibodies for PR were more variable (seven clones) than those for ER. Interpretation method used was Allred system in 20%, modified Allred system in 15%, report the % of positive tumor cells in 45%, positive/ negative in 15% and others in 5%. The expression rate of ER was ranged from 45.6% to 93% (mean 63.5%) and the expression rate of PR was ranged from 27% to 90% (mean 59.1%). The differences according to the numbers of breast cancer in each institute, primary antibodies, detection systems and interpretation methods did not influence to the expression rate of ER/PR, statistically (p>0.05). CONCLUSION: In Korea, the interlaboratory variance in ER/PR IHC procedure was too huge to make a standardized method. We suggest the proper quality control program such as ER/PR staining with positive internal and external controls and negative control might be better to aim at getting similar results among the different laboratories rather than trying to standardize the procedure.

A Multi-institutional Study of Interlaboratory Variance in the Estrogen and Progesterone Receptor Assays / 한국유방암학회지

PURPOSE: The expression of hormone receptors is the most reliable factor for predicting the responsiveness to hormonal therapy. At present, immunohistochemistry (IHC) is considered as a practically reliable method. This study was designed to examine the interlaboratory variance in immunohistochemical assays for estrogen receptor (ER) and progesterone receptor (PR) in Korea. METHODS: The Korean Study Group for Breast Pathology (KSGBP) made a questionnaire to know the current situation in HR assay in Korea. The questionnaire was sent to the members of KSGBP by e-mail, which were included eight questions relating to tissue handling, ER/PR IHC procedure and interpretation method. Forty laboratories replied with the completed questionnaire. RESULTS: All 40 laboratories were using formalin as a fixative. Pretreatment was performed using six different methods including autoclave (25%), microwave (30%) and full autostainer (15%). Primary antibodies for ER were SP1 in 40%, 6F11 in 27.5% and 1D5 in 32.5%. Primary antibodies for PR were more variable (seven clones) than those for ER. Interpretation method used was Allred system in 20%, modified Allred system in 15%, report the % of positive tumor cells in 45%, positive/ negative in 15% and others in 5%. The expression rate of ER was ranged from 45.6% to 93% (mean 63.5%) and the expression rate of PR was ranged from 27% to 90% (mean 59.1%). The differences according to the numbers of breast cancer in each institute, primary antibodies, detection systems and interpretation methods did not influence to the expression rate of ER/PR, statistically (p>0.05). CONCLUSION: In Korea, the interlaboratory variance in ER/PR IHC procedure was too huge to make a standardized method. We suggest the proper quality control program such as ER/PR staining with positive internal and external controls and negative control might be better to aim at getting similar results among the different laboratories rather than trying to standardize the procedure.

Malignant Rhabdoid Tumor of the Kidney Combined with Multicystic Dysplasia in a 5-year-old Child

Multicystic dysplastic kidney (MCDK) is a relatively common developmental anomaly in infants and children and has a good prognosis. In contrast, a malignant rhabdoid tumor of the kidney (MRTK) is one of the most lethal neoplasms of early life. However, the presentation of such a lethal tumor combined with multicystic dysplasia has not been reported to date. In this report, we describe a case of MRTK in a 5-yr-old girl who also had multicystic dysplasia. She was previously diagnosed with MCDK at birth due to a huge palpable mass on the right side of the abdomen. The right kidney was extensively replaced by numerous grossly dilated, variable-sized cysts. Microscopically, the tumor cells show a diffusely infiltrative growth pattern, which revealed large non-cohesive, round-to-polygonal tumor cells with vesicular nuclei. Some tumor cells had eccentric nuclei and large, round, eosinophilic cytoplasmic inclusions. There were metanephrons present, with the central ureteric bud and peripheral branches surrounded by condensing mesenchyma, immature glomeruli, and metaplastic cartilage in the adjacent parenchyma. To our knowledge, this is the first combined case of the two aforementioned diseases and this case may, in fact, suggest a new disease entity.

Erratum: Author's Name Correction / 한국유방암학회지

One of the authors' names was misprinted. The author list should be corrected as follows. Seok Kyoung Choi, Joon Jeong, Seung Ah Lee, Seung Hyun Hwang, Sung Gwe Ahn, Woo Hee Jung1, Hy-De Lee