Distinguishing prostatic from colorectal adenocarcinoma on biopsy samples: the role of morphology and immunohistochemistry

Identifying important microbial and genomic biomarkers for differentiating right- versus left-sided colorectal cancer using random forest models

BACKGROUND

Colorectal cancer (CRC) is a heterogeneous disease, with subtypes that have different clinical behaviours and subsequent prognoses. There is a growing body of evidence suggesting that right-sided colorectal cancer (RCC) and left-sided colorectal cancer (LCC) also differ in treatment success and patient outcomes. Biomarkers that differentiate between RCC and LCC are not well-established. Here, we apply random forest (RF) machine learning methods to identify genomic or microbial biomarkers that differentiate RCC and LCC.

METHODS

RNA-seq expression data for 58,677 coding and non-coding human genes and count data for 28,557 human unmapped reads were obtained from 308 patient CRC tumour samples. We created three RF models for datasets of human genes-only, microbes-only, and genes-and-microbes combined. We used a permutation test to identify features of significant importance. Finally, we used differential expression (DE) and paired Wilcoxon-rank sum tests to associate features with a particular side.

RESULTS

RF model accuracy scores were 90%, 70%, and 87% with area under curve (AUC) of 0.9, 0.76, and 0.89 for the human genomic, microbial, and combined feature sets, respectively. 15 features were identified as significant in the model of genes-only, 54 microbes in the model of microbes-only, and 28 genes and 18 microbes in the model with genes-and-microbes combined. PRAC1 expression was the most important feature for differentiating RCC and LCC in the genes-only model, with HOXB13, SPAG16, HOXC4, and RNLS also playing a role. Ruminococcus gnavus and Clostridium acetireducens were the most important in the microbial-only model. MYOM3, HOXC4, Coprococcus eutactus, PRAC1, lncRNA AC012531.25, Ruminococcus gnavus, RNLS, HOXC6, SPAG16 and Fusobacterium nucleatum were most important in the combined model.

CONCLUSIONS

Many of the identified genes and microbes among all models have previously established associations with CRC. However, the ability of RF models to account for inter-feature relationships within the underlying decision trees may yield a more sensitive and biologically interconnected set of genomic and microbial biomarkers.

Ascending colon cecal junction carcinoma with prostate metastasis: A case report and literature review

RATIONALE

Colon carcinoma is the most common type of cancer, and a leading cause of cancer-related death. Clinically, the most common sites of metastases from colon carcinoma are the liver, lungs, peritoneum, and lymph nodes, while the incidence of metastases to the prostate is low. There are few relevant studies on colon carcinoma, most of them being case reports.

PATIENT CONCERNS

A 76-year-old man treated with radical resection of right colon carcinoma due to primary poorly differentiated adenocarcinoma of the cecum. Postoperative pathological examination suggested that he had cancer at the junction of the ascending colon and the cecum. He had received adjuvant chemotherapy after surgery. One year later, he received transurethral plasma resection of the prostate due to urinary system discomfort. Postoperative pathological immunohistochemistry suggested prostate metastasis of colorectal carcinoma, and he received individualized treatment, but this produced no clear survival benefit.

DIAGNOSES

Ascending colon cecal junction carcinoma with prostate metastasis.

INTERVENTIONS

Radical resection, chemotherapy, anti-androgen therapy, surgery to relieve primary lesion obstruction symptoms, and local radiotherapy of the prostate.

OUTCOMES

At present, clinical cases of colon carcinoma with prostate metastasis are rare. By sharing a rare case of ascending colon cecal junction carcinoma with prostate metastasis and reviewing the relevant literature, this paper explores and optimizes the clinical treatment of colon carcinoma with prostate metastasis.

Prostate gland metastasis as a late relapse of rectal adenocarcinoma

We present a case report of a 49 year old patient with a known history of rectal adenocarcinoma treated with extended abdominal perineal resection. After five the patient was diagnosed with metastases to the prostate gland. This case stands out not only due to the infrequency of an onset of a colorectal tumor in the prostatic gland but also the late onset of the tumor. In these cases the differential diagnosis between a metastatic tumor and a primary urologic tumor is difficult due to similar morphology and histology, making the CDX-2 immunohistochemical maker expression an important tool to define the histopathology of the tumor.

Metastatic prostate cancer mimicking a rectal cancer: a case report

The most common presenting symptoms of prostate cancer, a common cancer in males worldwide, are lower urinary tract symptoms. In rare cases, however, urinary symptoms may not be apparent, and patients can present with gastrointestinal symptoms instead. Even rarer is the involvement of non-regional lymph nodes such as the cervical nodes. Here, we report a case of a 50-year-old male who initially presented with constipation and an enlarging left lateral neck mass. Further work-up revealed metastatic prostatic adenocarcinoma and the patient dramatically responded to chemotherapy, androgen deprivation therapy and bone support therapy. This case highlights the importance of considering a prostate malignancy in a male patient presenting with gastrointestinal symptoms and a neck mass even in the absence of lower urinary tract symptoms. Serum prostate specific antigen, pathologic findings and immunohistochemistry staining are important to guide the clinician in making the correct diagnosis and treatment.

Metastatic Prostate Cancer Presenting as a Rectal Polyp: A Rare Occurrence

The prostate is anatomically located anterior to the rectum. Due to this proximity, locally advanced tumors of the prostate can invade the rectal tissue; likewise, colorectal cancers can invade the prostate gland; This presents mainly as an invasive mass with an identifiable primary and is rarely an isolated lesion. Prostate cancer rarely affects the gastrointestinal tract. Few cases of prostate cancer metastatic to the gastrointestinal tract have been reported in patients with a known prostate cancer history. Initial diagnosis of prostate cancer diagnosed from a colonic polyp is rare. We report a case of metastatic prostate cancer first diagnosed from a rectal polyp. Our patient is a 76-year-old man who initially presented with fatigue and 20 pounds weight loss in five months. The patient never had a colonoscopy before the presentation. A colonoscopy was done, which showed multiple colonic polyps and a pathology report of metastatic prostate cancer from a 12 mm rectal polyp.

Diagnostic utility of immunohistochemical marker prostein for evaluation of primary and metastatic prostatic carcinomas

Context

The diagnosis of prostatic adenocarcinoma on histopathology depends on architectural and cytomorphological features supported by immunohistochemistry (IHC). Though all the prostate markers show excellent specificity, the sensitivity and percentage positivity vary.

Aims

In this study, we aim to study the expression of prostein in normal, benign, and malignant (primary and metastatic) lesions with particular emphasis on its utility in the differential diagnosis of poorly differentiated and metastatic prostatic adenocarcinoma along with a standard panel of IHC markers.

Settings and Design

This was both a prospective and retrospective as well as descriptive and observational study.

Subjects and Methods

All samples from patients with clinically suspected carcinoma prostate from both primary and metastatic sites from June 2015 to May 2016 were included in the study. Samples with difficulty in diagnosis on hematoxylin and eosin staining were subjected to a panel of IHC markers along with prostein.

Statistical Analysis Used

Receiver operating curve analysis and Chi-square test.

Results

Prostein showed a 100% sensitivity and specificity to identify normal prostatic epithelium, benign and premalignant lesions, and prostatic adenocarcinoma. Prostein showed a specificity of 100% in differentiating prostatic carcinoma from poorly differentiated urothelial carcinoma and in differentiating metastatic prostatic carcinoma from adenocarcinoma of nonprostatic origin.

Conclusions

Prostein is a new and promising prostate-specific marker that showed slightly more sensitivity and specificity than prostate-specific antigen. Thus, adding prostein to the IHC panel will greatly improve the detection of poorly differentiated primary and metastatic lesions of the prostate.

Expression of CDX2 in metastatic prostate cancer

The intestinal marker CDX2 has recently been found to stain a small percentage of primary prostate adenocarcinomas, but little is known of its expression in metastatic prostate cancers. We present a case of metastatic prostate adenocarcinoma that stained for CDX2 and highlight the confusion this may create when evaluating a carcinoma of unknown primary.

Prostate cancer solitary metastasis to anal canal: case report and review of literature

BACKGROUND

Here we present the first cases of prostate cancer solitary metastasis to anal canal.

CASE PRESENTATION

A 67-year-old male patient underwent radical prostatectomy with ilio-obturator lymphonodectomy in 2016 due to poorly differentiated ductal adenocarcinoma (Gleason 4 + 5(40%) = 9) pT3bN0. Two months later increasing PSA rate was noted and the patient started adjuvant intermittent androgen deprivation therapy combined with radiotherapy. Year after patient was admitted to the hospital complaining of dyschezia, pain in anal canal, and bloody stool. Digital rectal examination revealed an anal fissure with ulceration. A biopsy from ulcerated area showed poorly differentiated ductal adenocarcinoma of the prostate. Because there was no evidence of distant metastases on abdominal computed tomography (CT) scan and pelvic magnetic nuclear resonance imaging (MRI) and the only metastasis was in anal canal patient underwent laparoscopic abdominoperineal resection (APR). Postoperative course was uneventful and patient was discharged at postoperative day 7.

CONCLUSIONS

Our presented case is the first to describe prostate cancer solitary metastasis to anal canal and we always have to be aware of possible rare disease while assessing the patient with rectal bleeding. Biopsy most of the time is the only and the most reliable test to differentiate between the diseases.

Mucinous and secondary tumors of the prostate

Primary mucinous tumors and secondary tumors involving the prostate gland are relatively uncommon, however they have important diagnostic, therapeutic, and prognostic implications. The primary mucinous tumors of the prostate include mucinous (colloid) adenocarcinoma of the prostate, prostatic adenocarcinoma with mucinous features, and mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate). Mucinous adenocarcinoma of the prostate is defined as a primary prostatic acinar tumor characterized by the presence of at least 25% of the tumor composed of glands with extraluminal mucin. This diagnosis can only be made in radical prostatectomy specimens. Recent studies have shown that these tumors have a similar or in some cases better prognosis than conventional prostatic adenocarcinoma treated by radical prostatectomy. The preferred terminology for tumors that are composed of <25% extraluminal mucinous component in radical prostatectomy specimens is 'prostatic adenocarcinoma with mucinous features.' All cases of prostatic adenocarcinoma with extraluminal mucinous components in prostate needle core biopsies or transurethral resection of the prostate specimens are also referred to as 'prostatic adenocarcinoma with mucinous features.' Mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate) as the name implies, does not arise from prostatic acini or ducts, and is a distinct entity that arises from the prostatic urethra usually from urethritis glandularis or glandular metaplasia with malignant transformation, and is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. This tumor is aggressive and has a relatively poor prognosis. The most common secondary tumors that arise from adjacent organs and spread (direct extension or metastasis) to the prostate gland, include urothelial carcinoma of the bladder and colorectal adenocarcinoma. Other secondary tumors that may involve the prostate include metastatic epithelial tumors from several other sites, malignant melanoma and soft tissue tumors.

Efficacy of Immunohistochemical Staining in Differentiating a Squamous Cell Carcinoma in Poorly Differentiated Rectal Cancer: Two Case Reports

A rectal carcinoma, including primary an adenosquamous and a squamous cell carcinoma (SCC), is a very rare disease, accounting for 0.025% to 0.20% of all large-bowel malignant tumors. Because SCCs have a higher mortality than adenosquamous carcinomas, determining whether the primary rectal cancer exhibits an adenomatous component or a squamous component is important. While differentiating between these 2 components, especially in poorly differentiated rectal cancer, is difficult, specific immunohistochemical stains enable accurate diagnoses. Here, we report the use of immunohistochemical stains to distinguish between the adenomatous and the squamous components in 2 patients with low rectal cancer, a 58-year-old man and a 73-year-old woman, who were initially diagnosed using the histopathologic results for a poorly differentiated carcinoma. These data suggest that using these immunohistochemical stains will help to accurately diagnose the type of rectal cancer, especially for poorly differentiated carcinomas, and will provide important information to determine the proper treatment for the patient.

Rediscovering Secondary Tumors of the Prostate in the Molecular Era

Metastatic involvement of the prostate from noncontiguous solid tumors is a rare event occurring by means of vascular dissemination. The reported cases of biopsy and surgical samples with metastatic involvement have increased; however, a comprehensive understanding of secondary tumors of the prostate is currently missing. Metastases to the prostate carry a dismal prognosis and may pose serious diagnostic challenges to both clinicians and pathologists, with crucial therapeutic implications. Secondary tumors of the prostate spread more frequently from the digestive tract, the lung, and the kidney. The integration of clinicoradiologic data with appropriate pathologic and immunohistochemical analyses is essential for the identification and the characterization of secondary tumors of the prostate, whereas molecular analyses could provide additional and complementary information, enabling precise diagnosis and appropriate clinical management. Patients with solitary metastases could benefit from prostatic resection and adjuvant therapy, whereas in cases of disseminated diseases, symptom control may be obtained with palliative procedures. The purpose of this review was to assess the current state of knowledge of secondary tumors involving the prostate gland and to discuss short-term future perspectives, while providing a practical approach to these uncommon conditions for pathologists and oncologists.

Morphologic Updates in Prostate Pathology

In the past several years, modifications have been made to the original Gleason system with resultant therapeutic and prognostic implications. Several morphologic variants of prostatic adenocarcinoma have also been described. Prostate pathology has also evolved over the years with the discovery and utility of new immunohistochemical stains. The topics discussed in this update include the Gleason grading system, prognostic grade grouping, variants of prostatic adenocarcinoma, and the application of immunohistochemistry to prostate pathology.

Genetic variants at 1q32.1, 10q11.2 and 19q13.41 are associated with prostate-specific antigen for prostate cancer screening in two Korean population-based cohort studies

Prostate-specific antigen (PSA) levels are affected by non-cancerous conditions such as benign prostatic hyperplasia, inflammations, and inherited factors. To search for genetic variants associated with PSA levels, we conducted a genome-wide association study (GWAS) using a two-stage design. A total of 554 men from the Korean Cancer Prevention Study-II were used as a discovery stage and 1575 men collected by the Korean Genome Epidemiology Study were used as a replication stage. Analysis by Genome-wide Human single-nucleotide polymorphism (SNP) array 5.0 was performed by using DNAs derived from venous blood. We analyzed the association between genetic variants and PSA levels using multivariate linear regression models, including age as a covariate. We detected 12 genome-wide significant signals on chromosome 1q32.1, 10q11.2, and 19q13.41 between PSA levels and SNPs. The top SNP associated with log PSA levels was rs2153904 in SLC45A3 (p values, 5.24×10(-9) to 2.00×10(-6)). We also investigated GWAS using 754 subjects from KCPS-II cohort whether our genome-wide significant loci were associated with a risk of prostate cancer (PCa) (200 PCa cases and 554 controls). Three of the SNPs on 10q11.2, rs7077830, rs2611489, and rs4631830, were associated with a risk of PCa. However, two loci, 1q32.1 and 19q13, were not significantly associated with a PCa risk. We suggest that our results for some but not all PCa risk SNPs to be associated with PSA levels could be used as an evidence for the advance of individual PCa screening strategies, such as applying a personalized cutoff value for PSA.

Biopsy sampling and histopathological markers for diagnosis of prostate cancer

Prostate cancer is one of the most common malignant tumors and a leading cause of cancer-related morbidity and mortality. Irrespective of the method that allows for risk stratification of prostate cancer suspects, diagnosis relies on tissue sampling through prostate biopsy and subsequent histopathological evaluation. This provides critical information about disease aggressiveness, which is required for adequate patient management. Prostate biopsy methods have significantly evolved over the years, including the definition of indications, sampling schemes and use of imaging techniques (ultrasound and MRI) that allow for more accurate tissue sampling. In response to the challenges emerging from more precise collection of minute prostate tissue samples for analysis, histopathological assessment should include not only the observation of routinely stained sections, but also, and increasingly so, a series of ancillary techniques, especially immunohistochemistry, which increment the accuracy of prostate cancer diagnosis and may provide relevant information to guide patient management.

Factors associated with the survival of prostate cancer patients with rectal involvement

BACKGROUND

Prostate cancer patients with rectal involvement are rare, and the factors associated with the survival of these patients are yet to be elucidated.

PATIENTS AND METHODS

We collected data on patients who were admitted to our hospital for prostate cancer in the last thirteen years and of those in studies in the literature. The associations of clinical characteristics with survival were evaluated using Cox regression models.

RESULTS

This study included 94 patients (5 admitted to our hospital and 89 from studies in the literature) of prostate cancer with rectal involvement. 11 patients in the group of synchronous rectal involvement at first cancer diagnosis (n = 58) and 23 patients in the group of metachronous diagnosis of rectal involvement (n = 29) died at the latest follow up. The estimated overall survival rate (% ± SE) at 1, 3, and 5 years were 68.3 ± 5.3%, 54.4 ± 7.2%, and 38.1 ± 11.1%, respectively. In the Cox univariate analysis, Asian prostate cancer (p = 0.001) was associated with better survival, while rectal bleeding (p = 0.043), metachronous presentation of development of rectal involvement (p = 0.000), prior hormonal therapy (p = 0.000) and extrarectal metastases (p = 0.054) were associated with poor survival. In multivariate analysis, prior hormone therapy (HR = 14.540, p = 0.000) and rectal bleeding (HR = 2.195, p = 0.041) retained independent poor prognostic values. There were 13 patients survived for more than 3 years, the longest survival time was 96 months. Total pelvic extenteration (TPE) combined with hormonal therapy in 12 hormone-untreated prostate cancer give us six of thirteen long-term survivors for more than 3 years in this series.

CONCLUSIONS

Our findings suggest that rectal involvement does not necessarily predict a worse outcome when presenting as a previously hormone-untreated disease and that the prognosis was worse when presenting as a hormone relapsed disease. Prior hormone therapy and rectal bleeding were associated independently with a significantly poor overall survival in prostate cancer patients with rectal involvement. TPE combined with hormonal therapy appears to confer better overall survival in hormonally untreated patients.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1604504118106105.

Differentiating rectal carcinoma by an immunohistological analysis of carcinomas of pelvic organs based on the NCBI Literature Survey and the Human Protein Atlas database

The treatments and prognoses of pelvic organ carcinomas differ, depending on whether the primary tumor originated in the rectum, urinary bladder, prostate, ovary, or uterus; therefore, it is essential to diagnose pathologically the primary origin and stages of these tumors. To establish the panels of immunohistochemical markers for differential diagnosis, we reviewed 91 of the NCBI articles on these topics and found that the results correlated closely with those of the public protein database, the Human Protein Atlas. The results revealed the panels of immunohistochemical markers for the differential diagnosis of rectal adenocarcinoma, in which [+] designates positivity in rectal adenocarcinoma and [-] designates negativity in rectal adenocarcinoma: from bladder adenocarcinoma, CDX2[+], VIL1[+], KRT7[-], THBD[-] and UPK3A[-]; from prostate adenocarcinoma, CDX2[+], VIL1[+], CEACAM5[+], KLK3(PSA)[-], ACPP(PAP)[-] and SLC45A3(prostein)[-]; and from ovarian mucinous adenocarcinoma, CEACAM5[+], VIL1[+], CDX2[+], KRT7[-] and MUC5AC[-]. The panels of markers distinguishing ovarian serous adenocarcinoma, cervical carcinoma, and endometrial adenocarcinoma were also represented. Such a comprehensive review on the differential diagnosis of carcinomas of pelvic organs has not been reported before. Thus, much information has been accumulated in public databases to provide an invaluable resource for clinicians and researchers.

Review of small cell carcinomas of the prostate

Small cell carcinoma of the prostate is a rare neoplasm, with only a few series hitherto reported. A little less than half of the cases are associated with conventional acinar adenocarcinoma, which are usually high grade. Although consensus has not been reached, the majority of patients with small cell neuroendocrine carcinoma of the prostate have advanced disease at diagnosis and disproportionally low PSA levels compared to patients with conventional acinar adenocarcinoma. Treatment consists mainly of chemotherapy associated with surgery. Radiation therapy is reserved for selected cases. This study reviews the most up-to-date information on small cell carcinomas of the prostate.

Metastasis of a cecal adenocarcinoma to the prostate five years after a right hemicolectomy: a case report

Introduction

Prostatic metastasis from a primary bowel adenocarcinoma has been only rarely reported in the medical literature. The case reported here is rare in the fact that the primary tumor was from a right-sided bowel adenocarcinoma. It is unusual because initial immunostaining was not fully conclusive, and so a relatively new method of immunostaining, CDX2, was used to ascertain its histopathology.

Case presentation

We describe the case of a 54-year-old Caucasian man who had a right hemicolectomy for a primary cecal adenocarcinoma, which was completely excised. Following the procedure, he received adjuvant chemotherapy. Computed tomography scans showed no evidence of local recurrence or metastatic disease. Then, five years later, he presented to his general practitioner with urinary symptoms. An abnormal prostate was palpated on digital rectal examination. Trans-rectal prostatic biopsies were performed, which showed colorectal metastases within the prostate gland. This was confirmed with CDX2 immunohistochemistry. There was no further evidence of distant metastases on positron emission tomography-computed tomography scans.

Conclusions

This case demonstrates a rare isolated hematogenous spread to the prostate from a primary cecal adenocarcinoma, several years after definitive treatment and excision. This highlights the importance of accurate immunohistochemistry and imaging in planning further management and treatment.

Prostate cancer invading the rectum: a clinicopathological study of 18 cases

AIMS

Prostate cancer may involve the rectum and cause severe perineal pain. The aim of this study was to understand the rectal involvement by prostate cancer and its clinical significance.

METHODS

We evaluated pathological and clinical features of 18 cases of prostate cancer with rectal involvement.

RESULTS

All patients presented with intractable perineal pain. Twelve patients received rectal biopsies, which revealed poorly differentiated prostatic adenocarcinoma (n = 6), squamous cell carcinoma (n = 3), angiosarcoma (n = 1), or no tumour (n = 2). All patients received palliative total pelvic exenteration, which demonstrated prostate cancer invading the rectal wall. In these resection specimens, the tumour consisted of poorly differentiated prostatic adenocarcinoma (n = 16), squamous cell carcinoma (n = 1), or angiosarcoma (n = 1). In addition, six cases of prostatic adenocarcinomas also showed focal squamous (n = 3) or high-grade neuroendocrine (n = 3) differentiation. Nine patients died at a mean time of 18 months (range, 2-69 months) after surgery. The remaining nine patients were alive with a mean follow-up time of 15 months (range, 3-34 months), but four patients developed distant metastases.

CONCLUSIONS

Prostate cancer with rectal involvement often develops heterogeneous differentiation and carries a dismal prognosis.

Secondary neoplasms of the urinary system and male genital organs

BACKGROUND AND AIMS

In this review we discuss those secondary tumours involving the urinary system and male genital organs that can pose differential diagnostic difficulties with primary lesions, and highlight morphological and ancillary features that could be helpful in reaching a proper assignment of primary origin.

MATERIALS AND METHODS

Based on MEDLINE database searches all reports of secondary tumours involving the urinary system (kidney and bladder) and male genital organs (prostate, testis and penis) were examined.

RESULTS AND DISCUSSION

Involvement by a secondary tumour occurs either as a metastasis or by direct extension. Among non-genitourinary primary sites, colorectal, pulmonary, skin (melanoma) and breast are the most common contributors. Secondary spread from a genitourinary site primary tumour to another genitourinary organ occurs most frequently between the prostate and urinary bladder, given the intimate topographic proximity of the two. The prognosis is very poor, as the secondary tumour usually occurs in patients with carcinoma in the late stages. Few secondary tumours have distinctive histological and immunohistochemical features, making it difficult to make the appropriate diagnosis. Hence, knowledge of the history and clinical setting are particularly important in these cases.

CONCLUSION

The urinary system and male genital organs are not common sites for secondary tumours. They often go either undiagnosed or misdiagnosed in the clinical follow-up of patients with cancer. Accurate diagnosis is essential because of differing therapeutic approaches compared with a primary neoplasm.

Diagnostic utility of p501s (prostein) in comparison to prostate specific antigen (PSA) for the detection of metastatic prostatic adenocarcinoma

Background

Immunohistochemical detection of prostate specific antigen (PSA) is widely used to identify metastatic prostatic adenocarcinoma. However, PSA may not be expressed in some poorly differentiated prostatic carcinomas and its immunoreactivity has been found in some non-prostatic tissues. P501s (prostein) is a prostate-specific marker that is expressed in the cytoplasm of benign and malignant prostatic glandular cells. It has not been detected in any other normal or malignant tissues. The purpose of this study was to evaluate the expression of P501s in metastatic prostatic adenocarcinoma and compare its expression with PSA.

Methods

Immunohistochemical stains with anti-P501s antibodies were performed on 5-micron sections of tissue microarray (TMA) specimens. The TMA is constructed with normal donor prostates (NDP), prostatic adenocarcinoma (PRCA), non-neoplastic prostatic tissues adjacent to malignant glands (NAT), benign prostatic hyperplasia (BPH), high-grade prostatic neoplasia (PIN), metastatic adenocarcinoma to lymph nodes (MLN), metastatic adenocarcinoma to other sites (MC), and samples of benign testis, colon, adrenal and kidney. The two groups of metastatic lesions were also subjected to stains with antibodies to PSA. A composite score (ranging from 0 to 3) was assigned to score intensity of staining.

Results

Granular staining pattern of p501s was seen in all benign glands (score = 1.77 – 2.1) and malignant acini (score = 1.52) at the apical aspect of cytoplasm, predominantly adjacent to the nuclei. No staining was observed in controls including testis, colon, adrenal and kidney. The MLN group received a score of 1.0, with 10% of cases negative for p501s. The MC cases had a score of 0.64, with 16.7% of case showing loss of p501s expression. Although the metastatic lesions demonstrated similar rate of negative expression with PSA antibody, only 2 MC cases (3.3%) showed simultaneous negative stains for both P501S and PSA.

Conclusion

P501s is an organ specific marker for benign and malignant prostatic epithelial cells. Its characteristic cytoplasmic stain pattern provides an additional valuable immunomarker for detection of metastatic prostatic malignancy, even though the intensity of its expression is reduced, as in the case with PSA. Simultaneous stains with P501S and PSA will greatly improve the detection rate and identify a significant majority of the metastases.