M Varma

Diagnostic utility of immunohistochemistry in morphologically difficult prostate cancer: review of current literature

Immunohistochemistry is widely used to distinguish prostate cancer from benign mimics and to establish the prostatic origin of poorly differentiated carcinoma. We critically review the recent advances in prostate cancer immunohistochemistry, including the introduction of newer basal cell markers such as p63 and the discovery of the overexpression of α‐methylacyl coenzyme A racemase (AMACR) in prostate cancer. The description of newer urothelial markers to aid the distinction of prostate cancer from urothelial carcinoma is also presented together with refinements in the quality control of PSA and PSAP immunostaining. Although AMACR is a useful immunohistochemical marker for prostate cancer, it has significant limitations. These limitations are discussed and the need for interpreting AMACR immunoreactivity in the appropriate morphological context and in conjunction with basal call markers is emphasized. We also describe the utility of an immunohistochemical panel composed of PSA, PSAP and high molecular weight cytokeratin for distinguishing poorly differentiated prostate cancer from high‐grade urothelial carcinoma. A morphological differential diagnosis based selection of immunohistochemical markers is highlighted as a novel approach in the diagnosis of prostate cancer in routine surgical pathology practice.

High molecular weight cytokeratin antibody (clone 34βE12): a sensitive marker for differentiation of high‐grade invasive urothelial carcinoma from prostate cancer

Aims:  There is no well‐established positive immunomarker for urothelial carcinoma. We evaluated the diagnostic utility of high molecular weight cytokeratin (HMWCK) antibody clone 34βE12 in differentiating high‐grade invasive urothelial carcinoma from prostate cancer.

Technical variations in prostatic immunohistochemistry: need for standardisation and stringent quality assurance in PSA and PSAP immunostaining

Aims: To assess variations in prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) immunohistochemistry with particular reference to the antibody type (monoclonal or polyclonal) and the tissues used for optimising immunostaining conditions and as external positive controls. Methods: A questionnaire was sent to all laboratories registered with the UK National External Quality Assurance Scheme for immunohistochemistry enquiring about the immunohistochemical methods routinely used for the diagnosis of prostate cancer. Results: Responses were received from 220 (68%) laboratories. All UK respondents routinely performed PSA immunostaining but PSAP immunostaining was available in only 57% of these laboratories. Monoclonal anti-PSA, polyclonal anti-PSA, monoclonal anti-PSAP, and polyclonal anti-PSAP were used by 40%, 60%, 29%, and 27% of UK respondents, respectively. Benign prostate tissue was most commonly used to determine optimal antibody dilutions and as external quality control for PSA/PSAP, with only 6% and 3% of respondents, respectively, including high grade prostate cancer in the tissues used for these purposes. Conclusions: The wide variation in the methods used highlights the need for standardisation and more stringent quality assurance of the immunohistochemical staining techniques used for PSA and PSAP. The widespread use of benign prostate tissue to determine optimal antibody dilutions and as an external positive control for PSA and PSAP immunostaining is of particular concern because this approach may result in a method that is not sufficiently sensitive to detect the reduced PSA and PSAP expression associated with high grade prostate cancer.

Prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) immunoreactivity in benign seminal vesicle\ejaculatory duct epithelium: a potential pitfall in the diagnosis of prostate cancer in needle biopsy specimens.

prostate specific acid phosphatase (PSAP) immunoreactivity in benign seminal vesicle/ejaculatory duct epithelium: a potential pitfall in the diagnosis of prostate cancer in needle biopsy specimens Sir: Seminal vesicle ⁄ ejaculatory duct (SVED) epithelium is not uncommonly represented in prostate needle biopsy specimens and occasionally may be difficult to distinguish from prostate cancer. Immunohistochemistry using antibodies to prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) has been recommended to distinguish SVED from prostate cancer in such morphologically equivocal cases. However, focal, generally weak PSA immunoreactivity has been reported in benign seminal vesicles and we have observed similar PSAP positivity in seminal vesicles (unpublished observation). The mechanism of PSA ⁄ PSAP expression in seminal vesicles is uncertain. One explanation could be retrograde movement of PSA into the seminal vesicles with subsequent uptake by the seminal vesicle epithelium. If this hypothesis is correct, a greater degree of PSA ⁄ PSAP immunoreactivity would be expected in the intraprostatic ejaculatory duct compared with the seminal vesicles. Hence, we evaluated the immunohistochemical expression of PSA and PSAP in the intraprostatic portion of the ejaculatory duct. One section of the prostate gland including the intraprostatic portion of the ejaculatory duct and one section of seminal vesicle from each of nine radical prostatectomy specimens were immunostained using monoclonal anti-PSAP (clone PASE ⁄ 4LJ; Dako Corp., Ely, Cambridgeshire, UK; applied at 1 : 200 dilution for 45 min at room temperature) and polyclonal anti-PSA (catalogue number A0562; Dako Corp.; applied at 1 : 3200 dilution for 45 min at room temperature) after microwave pretreatment of the sections (20 min in 10 mmol ⁄ l concentration of EDTA at pH 7.0). Appropriate positive and negative controls were included. Immunohistochemical expression of PSA and PSAP was observed within the intraprostatic ejaculatory duct in all nine cases (Figures 1 and 2). This immunoreactivity was diffuse (>50% cells positive) in eight (89%) of these cases with each antibody. In the remaining case about 30% of the cells of the intraprostatic ejaculatory duct expressed PSA and PSAP. The intensity of staining with both markers ranged from weak to strong, with at least moderate staining intensity in five (56%) and eight (89%) cases for PSA and PSAP, respectively. The immunoreactivity with anti-PSA and anti-PSAP was comparable, although the positivity tended to be more diffuse with the former and more intense with the latter. PSA and PSAP positivity in sections from the corresponding seminal vesicles was generally weaker and more patchy. In view of the possibility of non-specific crossreaction of polyclonal anti-PSA with some other antigen in SVED epithelium, the intraprostatic ejaculatory duct from three representative cases was immunostained with monoclonal anti-PSA. In all three cases Figure 1. Intense diffuse prostate specific antigen immunoreactivity in intraprostatic ejaculatory duct.

Variations in the processing of prostatic needle cores in the UK; what is safe?

Aims: To determine the variation in the processing of prostatic needle cores in the UK and to compare the results with suggested guidelines. Methods: A standard questionnaire was sent to 210 pathology departments enquiring about current practices. Results: One hundred and thirty replies were received, which showed considerable variation in current methods. The number of cores received for each case ranged from three to 21, with the number of cores processed for each cassette varying from one to 10. Sixty per cent of centres used no special embedding techniques, and the number of sections cut for each case varied from two to 128, with a median of 12 sections for each case. Forty two per cent of laboratories did not take spare slides for immunochemistry. Conclusions: There is great variation in the processing of prostatic cores in the UK. In particular, some laboratories process a large number of cores in each cassette and do not use special embedding techniques. At present there are no established guidelines for the processing of these specimens. Enhanced techniques may well increase the sensitivity of the test but would increase the workload and costs to the pathology department. In view of the increasing workload from these specimens, a consensus for their optimum processing is required.

Gleason drift in the NIHR ProtecT study

There is increasing evidence of Gleason score (GS) drift in prostatic core biopsies during the last two decades. The ProtecT study is a randomized controlled study and provides an excellent cohort to study the effect of time, prostate‐specific antigen (PSA) level, perineural invasion, tumour length and age on GS.

Paraganglion of the prostate gland: an uncommon mimic of prostate cancer in needle biopsies

a GIST because of c-kit positivity and the presence of an exon 11 mutation within the c-kit gene. Seminomas, in contrast to GISTs, rarely have exon 11 mutations but often harbour mutations within the exon 17 of c-kit. However, after examination of representative tumour material, histological analysis highlighted the diagnosis of a seminoma, which was also confirmed by immunohistochemistry with antibodies to M2A and sACE. M2A and sACE are markers for neoplastic germ cells of seminomas, and are not expressed in GISTs (unpublished observation). It has to be kept in mind that PLAP, though generally accepted as a reliable marker for intratubular germ cell neoplasia, testicular seminoma and embryonal carcinoma, is occasionally not expressed, especially in metastatic and extragonadal seminomas. We therefore suggest that specificity and sensitivity of PLAP, c-Kit, sACE and M2A as markers for extragonadal seminomas should be reconsidered and compared in more detailed further studies.

Radiotherapy after radical prostatectomy for adenocarcinoma of the prostate: a UK institutional experience and review of published studies

AIMS The role of radiotherapy to the prostate bed after radical prostatectomy is the subject of much debate. We carried out a retrospective analysis of all patients treated with either adjuvant radiotherapy (ART) or salvage radiotherapy (SRT) in a single UK cancer centre and compared outcomes with published studies. MATERIALS AND METHODS All patients receiving radiotherapy at any time after a radical prostatectomy were identified and data collected. Patients were referred for ART because of positive surgical margins. SRT was carried out in patients with a detectable or rising prostate-specific antigen (PSA) postoperatively. Patients received either 55 Gy in 20 fractions or 60-64 Gy in 30-32 fractions. All but eight patients were treated using three-dimensional conformal radiotherapy. Both groups were combined for statistical analysis. Biochemical progression-free survival (BPFS) was calculated and displayed using Kaplan-Meier curves. Cox regression was used for univariate and multivariate analysis. RESULTS In total, 40 patients received postoperative radiotherapy and had a 3-year overall BPFS of 64%. There was no significant difference in 3-year BPFS between ART and SRT (73% vs 61%, P=0.33). Univariate analysis showed that 3-year BPFS was significantly longer if the highest postoperative PSA was<0.5 ng/ml compared with> or =0.5 ng/ml (83% vs 47%, P=0.019), and if the Gleason grade was <7 compared with > or =7 (92% vs 49%, P=0.007). A PSA at diagnosis<10 ng/ml, positive surgical margins, absence of seminal vesicle involvement and neoadjuvant hormones were all associated with a trend towards improved BPFS. Patients with all of these factors had a 3-year BPFS of 91%. Multivariate analysis of the same parameters showed that only Gleason grade remained statistically significant (P=0.019). CONCLUSIONS The results from this series are in line with published studies, and support the evidence that prostate bed radiotherapy may affect biochemical control in a proportion of patients at risk of relapse. It is not clear whether ART in patients at high risk of relapse or SRT on relapse is most effective.

Potential unreliability of normal tissue as positive control in diagnostic immunohistochemistry of poorly differentiated carcinoma.

Judicious use of positive and negative tissue controls is an important part of technical quality assurance in immunohistochemistry. Positive controls may be ‘external’, where known positive tissue is immunostained in parallel with the test slide; or ‘internal’, with known positive tissue ⁄ cells present within the tested tissue section. Internal controls are generally considered superior to external controls, as the control cells have been subjected to identical conditions of fixation and immunostaining as the test cells. We describe two cases to demonstrate that even an apparently goodquality internal control result is not adequate proof of assay sensitivity. High molecular weight cytokeratin (HMWCK) antibody clone 34bE12 is commonly used to help distinguish high-grade urothelial carcinoma from prostatic adenocarcinoma, as it is consistently expressed by urothelial carcinoma, but is negative in prostatic cancer. The two cases described below were both referred to us for consultation with a differential diagnosis of urothelial versus prostatic carcinoma. Tumour cells were judged to be immunonegative for prostatic markers as well as 34bE12 immunostaining

High grade prostatic adenocarcinoma with a partly intraductal growth pattern producing a mimic of urothelial carcinoma in situ

High grade solid variants of prostatic adenocarcinoma and urothelial carcinoma can show overlapping histological features and their differentiation may require careful histological and immunohistochemical evaluation. The presence of surface urothelial carcinoma in situ is considered a helpful clue in support of a diagnosis of urothelial carcinoma. We present a series of three cases in which the high grade prostatic adenocarcinoma mimics urothelial carcinoma in situ, through a partly intraductal growth pattern within the prostatic duct system and partial replacement of the urothelium of the prostatic urethra. This may be a potential diagnostic pitfall, especially if present in small superficial mucosal biopsies, or when represented in samples from the bladder neck or penile urethra. A 70-year-old male subject underwent radical prostatectomy with bilateral iliac lymph node dissection for prostatic adenocarcinoma, following diagnosis on needle core prostatic biopsies performed for an elevated serum prostate specific antigen (PSA) of 40 μg/l. Sections from the prostate gland showed bilateral multifocal Gleason score 4+3=7 prostatic adenocarcinoma of microacinar type, predominantly in the posterior peripheral zones of the gland. Focally there was a higher grade malignant proliferation (figure 1A,B), partly within prostatic ducts and partly invading the stroma. There was necrosis with calcification and the cells generally lacked nucleoli. Some glandular spaces were identified. This intraductal process …