AAMJ, Vol.2, N. 2, April, 2004

Transcription

1 AAMJ, Vol.2, N. 2, April, 2004 DIAGNOSTIC VALUE OF CYTOKERATIN 5/6 COMPARED TO KERATIN 903 IN THE DIFFERENTIATION OF BENIGN FROM MALIGNANT GLANDS IN PROSTATIC LESIONS Sabah A. Fadel Department of Pathology, Assiut University Hospital SUMMARY Aims: Compare immunohistochemical expression of anti-basal cell antibodies K903 and CK 5/6 in benign and malignant prostatic glands, and determine their value in differentiation between benign and malignant glands. Methods and results: This study included 50 cases of prostatic lesions, 40 of them were benign prostatic hyperplasia and 10 cases were well differentiated adenocarcinoma. All cases were formalin fixed, paraffin embedded tissues. Immunostaining was done to all cases by K903, and CK5/6. All slides were evaluated using a semiquantitative analysis of staining: <25%, 25-50%, 50-75%, > 75% and > 95% of benign glands. Cases that showed no staining were restained to ensure no false negative. 38 of 40 cases (95%) showed staining in > 95% of benign glands with CK5/6 in contrast K903 staining was seen in <50% of benign glands in 7 of 40 (17.5%), 50-75% in 13 of 40 (32.5%), > 75% in 14 of 40 (35%), no cases showed > 95% staining for K903. In 6 of 40 (15%) K903 failed to stain any gland even after repeated staining. The pattern of staining was focal for K903 compared to continuous, uninterrupted fashion for CK5/6. Atrophic glands in the slides showed the same pattern of staining. Neither K903 nor CK5/6 stained malignant glands. Using a cut-off > 75% staining in benign glands the sensitivity of CK 5/6 and K903 was 97.5% and 35% respectively. Conclusions: CK 5/6 compared to K903 is considered excellent and sensitive marker for the differentiation between benign and malignant prostatic glands and can be used for the diagnosis specially in cases where suspicious glands are in question. INTRODUCTION Transurethral resection and needle biopsies specimens are now widely used for the diagnosis of different prostatic lesions. Pathologists are under increasing pressure to make a definitive diagnosis from these very small specimens. Often the only focus suspicious of carcinoma is a few small atypical glands. It is in these instances that pathologists need a specific marker to differentiate benign from malignant prostatic glands. The presence of a basal cell layer in prostatic glands is necessary for the glands to be called benign (1). From the basal cell specific antibodies are Keratin 903 (K 903) and 119

2 Sabah A. Fadel cytokeratin 5/6 (CK 5/6). K 903 antibodies (Clone 34 BEI 2) recognize a broad spectrum of high molecular weight keratins, including the 66, 51 and 49- KDa moieties (3,4). Recently, commercially available antibodies to cytokeratins 5 and 6 (CK 5/6) are large, closely related polypeptides that are found in complex epithelium (2). Their use lie in the identification of benign glands by positive staining. Thus, these stains are used to rule in the glands in question as benign. This study was done to compare immunohistochemical expression of K903 and CK 5/6 in benign and malignant prostatic lesions, and to evaluate their use to differentiate between benign and malignant glands. MATERIAL AND METHODS This study included 50 cases of prostatic lesions, there were 40 cases of benign prostatic hyperplasia (BPH), 6 of them showed atrophic glands, and 10 cases of well differentiated prostatic adenocarcinoma. The specimens were obtained by transurethral resection and by needle biopsies. The material was collected from the archives of the Pathology Department, Faculty of Medicine, Assiut University Hospital. All specimens were formalin-fixed and paraffinembedded. Cases were selected by reviewing the corresponding haematoxylin and eosin (H &E) stained slides. Sections containing cancer were selected to be well differentiated adenocarcinoma. Immunohistochemistry Immunohistochemical staining was performed using labelled streptavidin-biotin peroxidase technique (LSAB). Briefly, after being deparaffinized in xylene and rehydrated in ethanol, the sections were immersed in citrate buffer (0.01M, ph 6.5) and heated in a microwave oven for 10 minutes to retrieve antigen. The sections were incubated with the primary monoclonal antibody. Using antibodies to K903 (Enzo Diagnostics, New York, USA) and CK 5/6 (Roche Biomed/Boehringer-Mannheim, Indianapolis, USA); dilution 1:150 following the procedure indicated by Abrahams et al., (5). Immunohistochemical assessment In each case, the percentage of benign glands that stained for both markers was evaluated in a semiquantitive fashion using the following scale: <25%, 25-50%, 50-75%, >75% and >95%, lack of staining in clearly benign glands, as well as focal staining was noted. A final tabulation of percentage of glands stained in each case was made. 120

3 AAMJ, Vol.2, N. 2, April, 2004 RESULTS Our study included 40 cases of benign prostatic hyperplasia and 10 cases of well differentiated prostatic adenocarcinoma. K cases (15%), of benign prostatic hyperplasia k903 failed to stain any gland and repeated staining yielded similar results. In contrast, corresponding CK 5/6 stained slides from these cases showed positive staining of the benign glands. K903 staining of basal cells was observed in <50% of benign glands in 7 cases (17.5%), 13 cases (32.5%) showed staining in 50-75% of the benign glands, 14 cases (35%) showed >75% staining in benign glands and no cases showed >95% staining of benign glands. The staining pattern was noted to be focal in all cases (Fig 1). K903 was also focal in atrophic glands (Fig.2). Using a cut-off of >75% staining of benign glands, the sensitivity of K903 was 35%. All cases of prostatic adenocarcinoma were negative for K903. CK 5/6 CK 5/6 stained the basal cell in >95% of benign glands in 38 of the 40 cases (95%), one case (2.5%) showed >75% staining of benign glands and one case (2.5%) showed 50-75% staining of benign glands. The staining pattern was continuous in the basal cells of benign glands (Fig. 3). CK 5/6 was also showing continuous staining in atrophic glands (Fig. 4). Using a similar cut-off of >75% of benign glands staining, CK 5/6 had a sensitivity of 97.5%. All cases of prostatic adenocarcinoma were negative for CK 5/6. The results of both K903 and CK 5/6 staining are summarized in table (1). Table (1) : Summary of results of immunoreactivity for K903 and CK 5/6 Immunostain Percentage of benign glands staining 0% <50% 50-75% >75% >95% Keratin 903 N=40 6/40 7/40 13/40 14/40 0/40 (%) (15) (17.5) (32.5) (35) (0) Cytokeratin 5/6 N =40 0/40 0/40 1/40 1/40 38/40 (%) (0) (0) (2.5) (2. 5) (95) 121

4 Sabah A. Fadel Fig.(1) K903 immunostaining of benign prostatic hyperplasia showing focal staining of basal cell layer (X 100). Fig.(2) K903 immunostaining of atrophic gland showing focal staining of basal cell layer. (X200). Fig.(3) CK5/6 immunostaining of benign prostatic hyperplasia showing continuous staining of basal cell layer (X 100). Fig.(4) CK5/6 immunostaining of atrophic gland showing continuous staining of basal cell layer (X 200). 122

5 AAMJ, Vol.2, N. 2, April, 2004 DISCUSSION The presence of a basal cell layer in prostate glands is necessary for the glands to be called benign (1). Some authors have proposed that there may be a progressive loss of the basal cells in prostatic intraepithelial neoplasia (high grade PIN) (6). Occasionally, particularly in needle biopsies, a small focus of atypical glands is present in which basal cells are inconspicuous and a diagnosis of adenocarinoma is considered. In these cases the diagnostic utility of monoclonal antibodies to high molecular weight cytokeratins as markers of basal cells had been well established (7-9). Positive staining in an atypical focus proves that the glands in question are not carcinomatous, while absence of staining supports a diagnosis of adenocarcinoma in suspicious cases. The use of high molecular weight anti-keratin antibodies has been shown to decrease the number of equivocal diagnosis, thereby enhancing the sensitivity of the prostatic needle biopsy (10, 11 ). With regard to K903 antibodies, a number of authors have reported that the sensitivity of this marker is suboptimal (6, 11, 9). Hedrick and Epstein (4) studied the sensitivity of K903, and they found a discontinuous pattern of staining, which they defined as large areas of a gland devoid of staining interspersed with areas with clearly staining basal cells. A similar finding was reported by Wojno and Epstein (9) and Abrahams et al., (5). This was particularly problematic when dealing with small lesions or small amount of tissues. In this study 40 benign prostatic lesions, K903 stained the majority (>50%) of benign glands in 27 cases (67.5%). However, k903 stained (<50%) of benign glands in 7 cases (17.5%). There is complete absence of staining in 6 (15%) of these cases. The overall sensitivity of K903 in this study is much lower than that reported by Wojno and Epstein (9) and Abrahams et al., (5). This can be attributed to the different fixative used and to the different methods as they used frozen sections in their study. Several explanations was reported to clarify the patchy staining of benign glands by K903, Goldstein et al., (12) reported that attenuation of the basal cell layer occurs normally toward the periphery of some prostatic lobular and duct autpouchings, but Headrih and Epstein (4) and Varma et al., (13) reported that this may results from the fixation process, as they found that increased length of formalin fixation adversely affect basal cell immunoreacivity using antibodies to K903. With regard to CK 5/6 antibodies which are basal cell-specific, they have been most extensively studied in the lung (14-16 ), where they have been shown to stain only the basal cells of bronchial epithelium in normal lung. Immunoreactivity for CK 5/6 has been reported in squamous carcinomas of the lung, transitional cell carcinoma metastatic to lung and large cell undifferentiated carcinoma, while pulmonary adenocarcinomas generally are negative for the marker (15). CK 5/6 has been most widely used in the 123

6 Sabah A. Fadel distinction of epithelioid mesothelioma of the pleura from metastatic adenocarcinomas (14,15 ). Ordonez (15) reported that all 40 cases of epithlioid mesothelioma were positive whereas all 30 cases of pulmonary adenocarcinoma were negative. In addition, a variety of extrapulmonary adenocarcinoma were evaluated and all were negative for CK 5/6, including 8 cases of prostatic adenocarcinoma. Also Goldstein (17) reported that all cases of prostatic adenocarcinoma were negative for CK 5/6. The results of this study show that in 95% of the cases >95% of benign glands expressed intense staining in a continuous, uninterrupted fashion, in the two remaining cases one showed staining of >75% of benign glands and the other showed staining of >50% of benign glands and also in continuous, uninterrupted fashion. On the other hand there was a complete absence of staining in all adenocarcinoma. These results are go on with that, reported by Abrahams et al., (18). So CK 5/6 appears to be an excellent marker of prostatic basal cells, as well as a reliable discriminator between benign and malignant prostatic glands. Another important point is that CK 5/6 gives a good results in formalin-fixed tissues in comparison with K903, which is sensitive to both formalin fixation and length of fixation (13). In conclusion: CK 5/6 in comparison to K903 is considered an excellent and sensitive marker for the differentiation between benign and malignant prostatic glands and can be used for the diagnosis specially in cases where suspicious glands are in question. REFERENCES 1) Brawer MK., Peeld DM., Stamey TA and Bostwick DG (1985 ): Keratin immunoreactivity in the benign and neoplastic human prostate. Cancer Res. 45; ) Moll R., Frank WW., Schuller DI., Gelger B and Krepler R., (1982 ): The catalog of human cytokeratins: patterns of expression in normal epithelia, tumors and cultured cells. Cell 31; ) Gowm AM., and Vogel AM., (1984 ): Monoclonol antibodies to human intermediate filament proteins. Distribution of filament proteins in normal human tissues. Am. J. Pathol. 114; ) Hedrick L and Epstein JI (1989 ): Use of keratin 903 as an adjunct in the diagnosis of prostate carcinoma. Am J. Surg. Pathol. 13; ) Abrahams NA., Ormsby AH., and Brainard J., (2002 ): Validation of cytokeratin 5/6 as an effective substitute for keratin 903 in the differentiation of benign from malignant glands in prostate needle biopsies. Histopathology 44;

7 AAMJ, Vol.2, N. 2, April, ) Bostwick DG., and Brawer MK., (1987 ): Prostate intra-epithelial neoplasia and early invasion in prostatic cancer. Cancer 59; ) Dardik M., and Epstein JI., (2000 ): Efficiency of staining prostatic needle biopsies with high molecular weight cytokeratin. Hum. Pathol. 31; ) Brawer MK., Nagle RB., Pitts W., Freiha F., and Gamble ST (1989 ): Keratin immunoreactivity as an aid to the diagnosis of persistent adenocarcinoma in irradiated human prostate. Cancer 63; ) Wojno KJ., and Epstein JI., (1995 ): The utility of basal cell-specific anticytokertin antibody (34 beta EI2) in the diagnosis of prostate cancer. A review of 288 cases. Am. J. Surg. Pathol. 19; ) O Malley FP., Grignon DJ., and Shum DT.,(1990 ): Usefulness of immunoperoxidase staining with high-molecular-weight cytokeratin in the differential diagnosis of small acinar lesions of prostate gland. Virchows Arch Pathol. Anat. Histopathol. 417: ) Shah IA., Schlageter MO., Stinnetlt P., and Lechago J., (1991 ): Cytokeratin immunohistochemistry as a diagnostic tool for distinguishing malignant from benign epithelial lesions of the prostate. Mod. Pathol 4; , 12) Goldstein NS., Underhill J., Roszka J., and Neill JS., (1999 ): Cytokeratin 34 beta pattern assessment and electron microscopic study. Am.J. Clin. Pathol. 112; ) Varma M., Linden MD., and Amin MB., (1999 ): Effect of formalin fixation and epitope retrieval techniques on antibody 34 beta EI2 immunostaining of prostatic tissues. Mod. Pathol. 12: ) Clover J., Oates J., and Edwards C (1997 ): anti-cytokeratin 5/6: a positive marker for epithelioid mesothelioma. Histopathology 31; ) Ordonez NG. (1998 ): Value of cytokeratin 5/6 immunostaining in distinguishing epithelial mesothelioma of the pleura from lung adenocarcinoma. Am. J. Surg. Pathol. 22; ) Cury PM., Butcher DN., Fisher C., Corrin B., and Nicholson AG., (2000 ): Value of the mesothelium associated antibodies thrombomodulin, cytokeratin 5/6, calretinin and CD411 in distinguishing epithelioid pleural mesothelioma from adenocarcinoma metastatic to the pleura. Mod. Pathol. 13; ) Goldstein NS., ((2002 ): Immunophenotypic characterization of 225 prostate adenocarcinomas with intermediate or high Gleason scores. Am. J. clin. Pathol. 3:

8 Sabah A. Fadel 18) Abrahams NA., Bostwick DG., Ormsby AH., Qian J., and Brainard J., (2003 ): Distinguishing atrophy and high-grade prostatic intraepithelial neoplasia from prostatic adenocarcinoma with and without previous adjuvant hormone therapy with the aid of cytokeratin 5/6. Am. J. clin. Pathol. 170 (3): الممخص العربي القيمت التشخيصيت لسيتوكيراتين 6/5 مقارنت بكيراتين 903 فى التفرقت بين الغذد الحميذة من الخبيثت فى آفاث البروستاتا صباح أحمذ فاضل قسم الباثولوجيا بمستشفى اسيوط الجامعي الهدف: مقارنة تعبير األجسام المضادة لمخاليا القاعدية ك 903 وس ك 6/5 فى غدد البروستاتا الحميدة والخبيثة بكيمياء األنسجه المناعيه ولتحديد استخدامهم فى التفرقة بين الغدد الحميدة والخبيثة. الطريقة والنتائج: أحتوى هذا البحث عمى 50 حالة من آفات البروستاتا منهم 40 حالة تضخم بروستاتا حميد وعشر حاالت كارسينوما الغدد جيدة التمييز. كل الحاالت كانت مثبتة فى الفورمالين ومطمورة فى الب ارفين. وعممت الصبغة المناعية لجميع الحاالت ب ك 903 وس ك 6/5 وتم تقييم جميع الحاالت بأستخدام التحميل شبه كمى لمصبغة: > %75 و< %95 فى الغدد الحميدة. %75-50.%50-25 %25 < الحاالت التى لم تظهر بها الصبغة تم إعادة صبغتها لمتأكد من انعدام السمبية الكاذبة. 38 من 40 حاله )%95( أظهرت الصبغة فى > %95 من الغدد الحميدة فى س ك 6/5 عمى العكس صبغة ك 903 ظهرت فى > %50 من الغدد الحميدة فى 7 من )%17.5( 40 %75-50 فى 13 من 40 )%32.5( < %75 فى 14 من )%35( 40 ولم نجد حاالت بها %95 صبغة ب ك 903. وفى 6 من )%15( 40 ك > 903 فشل فى صبغ أى غدة حتى بعد إعادة الصبغة وكان نمط الصبغةمتقطع ل ك مستمر وغير متقطع ل س ك ك 903 وال س ك 903 مقارنة بنمط 6/5. والغدد الضامرة عمى الش ارئح أظهرت نفس نمط الصبغة. ولم يصبغ 6/5 الغدد الخبيثة. وبأستخدام خط فاصل وك 903 كانت %97.5 %35 عمى التوالى. الخالصة: يعتبر س ك < %75 لمغدد الحميدة فحساسية س ك 6/5 6/5 مقارنة ب ك 903 مثالى ومميز حساس لمتفرقة بين غدد البروستاتا الحميدة من الخبيثة. ويمكن أستخدامه لمتشخيص خصوصا فى الحاالت التى بها غدد مريبة وبها شك