Paneth cell-like change and small cell carcinoma of the prostate. Two divergent forms of prostatic neuroendocrine differentiation

Three-dimensional ultrastructural and anatomical analysis of prostatic neuroendocrine cells in mice

BACKGROUND

A few studies have examined the ultrastructure of prostatic neuroendocrine cells (NECs), and no study has focused on their ultrastructure in three dimensions. In this study, three-dimensional ultrastructural analysis of mouse prostatic NECs was performed to clarify their anatomical characteristics.

METHODS

Three 13-week-old male C57BL/6 mice were deeply anesthetized, perfused with physiological saline and 2% paraformaldehyde, and then placed in 2.5% glutaraldehyde in 0.1 M cacodylate (pH 7.3) buffer for electron microscopy. After perfusion, the lower urinary tract, which included the bladder, prostate, coagulation gland, seminal vesicle, upper vas deferens, and urethra, was removed, and the specimen was cut into small cubes and subjected to postfixation and en bloc staining. Three-dimensional ultrastructural analysis was performed on NECs, the surrounding cells, tissues, and nerves using focused ion beam/scanning electron microscope tomography.

RESULTS

Twenty-seven serial sections were used in the present study, and 32 mouse prostatic NECs were analyzed. Morphologically, the NECs could be classified into three types: flask, flat, and closed. Closed-shaped NECs were always adjacent to flask-shaped cells. The flask-shaped and flat NECs were in direct contact with the ductal lumen and always had microvilli at their contact points. Many of the NECs had accompanying nerves, some of which terminated on the surface in contact with the NEC.

CONCLUSIONS

Three-dimensional ultrastructural analysis of mouse prostatic NECs was performed. These cells can be classified into three types based on shape. Novel findings include the presence of microvilli at their points of contact with the ductal lumen and the presence of accompanying nerves.

Essential Updates in Grading, Morphotyping, Reporting, and Staging of Prostate Carcinoma for General Surgical Pathologists

CONTEXT.—

Within this decade, several important updates in prostate cancer have been presented through expert international consensus conferences and influential publications of tumor classification and staging.

OBJECTIVE.—

To present key updates in prostate carcinoma.

DATA SOURCES.—

The study comprised a review of literature and our experience from routine and consultation practices.

CONCLUSIONS.—

Grade groups, a compression of the Gleason system into clinically meaningful groups relevant in this era of active surveillance and multidisciplinary care management for prostate cancer, have been introduced. Refinements in the Gleason patterns notably result in the contemporarily defined Gleason score 6 cancers having a virtually indolent behavior. Grading of tertiary and minor higher-grade patterns in radical prostatectomy has been clarified. A new classification for prostatic neuroendocrine tumors has been promulgated, and intraductal, microcystic, and pleomorphic giant cell carcinomas have been officially recognized. Reporting the percentage of Gleason pattern 4 in Gleason score 7 cancers has been recommended, and data on the enhanced risk for worse prognosis of cribriform pattern are emerging. In reporting biopsies for active surveillance criteria-based protocols, we outline approaches in special situations, including variances in sampling or submission. The 8th American Joint Commission on Cancer TNM staging for prostate cancer has eliminated pT2 subcategorization and stresses the importance of nonanatomic factors in stage groupings and outcome prediction. As the clinical and pathology practices for prostate cancer continue to evolve, it is of utmost importance that surgical pathologists become fully aware of the new changes and challenges that impact their evaluation of prostatic specimens.

Mucin-producing tumors and tumor-like lesions involving the prostate: a comprehensive review

Mucin-producing tumors of the prostate include both primary and secondary tumors with mucinous differentiation or features involving the prostate gland. These tumors are relatively rare and have variable prognostic and therapeutic implications. Primary mucinous (colloid) adenocarcinoma of the prostate is defined as prostatic adenocarcinoma with mucinous differentiation involving 25% or more of the entire tumor. Another primary tumor of the prostate that may have mucinous features is primary mucin-producing urothelial-type adenocarcinoma of the prostate (mucinous prostatic urethral adenocarcinoma). Primary mucin-producing urothelial-type adenocarcinoma of the prostate is a distinct entity that typically arises from the prostatic urethra possibly from urethritis glandularis or glandular metaplasia with malignant transformation, and it is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. Signet ring cell tumors of the prostate, though rare, may also have mucinous features. Secondary tumors with mucinous differentiation that may involve the prostate include adenocarcinomas of the urinary bladder and colorectum. Pathologists should also be aware of mucin-producing tumor-like lesions involving the prostate, including mucinous metaplasia, and benign Cowper glands that may mimic malignancy. Herein we present an updated and comprehensive review of the clinicopathologic, immunohistochemical, molecular, and prognostic features of mucinous tumors and tumor-like lesions involving the prostate gland, with emphasis on mucinous prostatic adenocarcinoma and its mimickers, including potential diagnostic pitfalls.

Small cell carcinoma of the prostate after high-dose-rate brachytherapy for low-risk prostatic adenocarcinoma

In the present study, we describe an 80-year-old patient who developed prostatic small cell carcinoma (SCC) following high-dose-rate brachytherapy (HDR-BT) for low-risk prostatic adenocarcinoma. The patient received one implant of Ir-192 and 7 fractions of 6.5 Gy within 3.5 days, for a total prescribed dose of 45.5 Gy. A total of 27 months after HDR-BT, the patient complained of difficulty in urinating. His serum prostate-specific antigen (PSA) levels were 3.2 ng/ml. Systemic examination revealed an enlargement of the prostate, urethral stenosis, pelvic lymph node swelling and multiple lung and bone lesions. His serum neuron-specific enolase (NSE) levels were elevated to 120 ng/ml. A prostate needle biopsy was performed for pathological examination. Histologically, there were tumor cells with hyperchromatic nuclei and scant cytoplasm showing a solid or trabecular growth pattern. Immunohistochemically, they were positive for AE1/AE3, CD56 and synaptophysin, and negative for PSA, PAP and CD57. These findings are consistent with SCC of the prostate. A review of the prostate needle biopsy specimen prior to HDR-BT did not reveal any tumor cells positive for chromogranin A, nor synaptophysin. The final diagnosis was SCC of the prostate with local progression, with lung, lymph node and bone metastases. Three cycles of etoposide/cisplatin (EP) were administered. A greater than 50% decrease in the serum NSE levels was observed. However, there was no objective response. Due to the deterioration of the patient's general condition, EP was discontinued. One month later, his serum NSE showed a rapid increase to 210 ng/ml with aggressive local progression and the patient succumbed to the disease 5.5 months after the start of EP therapy.

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.

Unusual and Underappreciated: Small Cell Carcinoma of the Prostate

In recent years, attention has focused on the prognostic importance of neuroendocrine differentiation in prostate cancer. Focal neuroendocrine differentiation in prostatic adenocarcinoma is a frequent finding. Though controversial, the prevalence of neuroendocrine cells has been correlated with higher-grade malignancy and poor prognosis. As with other small cell tumors, production of ectopic neuropeptides has been reported. The rarity of the disease has precluded prospective randomized trials. Therapeutic regimens have mainly been modeled after those for small cell lung carcinoma. Here we review the literature to identify potential diagnostic, therapeutic, and prognostic factors. Evident from this review is the necessity for further research in the biology of small cell carcinoma progression, in order to improve therapy.

Small cell carcinoma of the prostate expressing prostate-specific antigen and showing syndrome of inappropriate secretion of antidiuretic hormone: an autopsy case report

An autopsy case of primary small cell carcinoma (SCC) of the prostate in a 68-year-old man is reported. The patient was admitted to hospital because of a bloody stool and suspected rectal cancer. However, a diagnosis of prostate cancer was made on the basis of a digital rectal examination, the serum level of prostate-specific antigen, and a needle biopsy of the prostate. The patient also experienced a syndrome of inappropriate secretion of antidiuretic hormone. He died 29 days after admission. At autopsy, the tumor had invaded the rectum, bladder and pelvic peritoneum. Metastases to the heart, vertebrae and lymph nodes were observed. Microscopically, the tumor was composed of small round cells that showed a solid growth pattern. Rosette formations were observed. Immunohistochemically, the tumor cells were positive for a prostatic epithelial marker and neuroendocrine markers. A high level of antidiuretic hormone was detected in the tumor tissue. To our knowledge, this is the first reported case of SCC of the prostate in which both a prostatic epithelial marker and neuroendocrine markers have been found in the same tumor. This finding supports the hypothesis that SCC of the prostate originates from a multipotential stem cell of the prostatic epithelium.

Morphology and therapeutic strategies for neuroendocrine tumors of the genitourinary tract

BACKGROUND

Although many articles have been published regarding neuroendocrine tumors (NET) and neuroendocrine carcinomas of both low- and high-grade malignancy (NEC) of the genitourinary tract, the histologic diagnosis and therapeutic strategies for treating these entities remains difficult. In the current study the author discusses the significant differences between NET and NEC of the urinary bladder and the prostate, including therapeutic consequences.

METHODS

Four hundred eighty neoplasms of the urinary bladder and prostate with a small cell pattern were analyzed not only on slides stained with hematoxylin and eosin but also by means of immunohistochemical stains demonstrating a neuroendocrine origin. The avidin-biotin complex method was used with the following markers: MIB-1, chromogranin A (Chr A), synaptophysin (SNP), cytokeratin (CK) 34betaE12, CK20, androgen receptor (AR), and prostate specific antigen (PSA).

RESULTS

Twenty tumors of the urinary bladder and 26 of the prostate demonstrated a diffuse neuroendocrine pattern. Only two patients were found to have a low-grade NEC of the prostate with a low proliferative index but strong expression of neuroendocrine markers. All other patients with small cell neuroendocrine carcinomas of the bladder and prostate demonstrated extremely high proliferation activity (>80%) and expressed Chr A and SNP. CK34betaE12, 20, PSA, and AR were not found to be expressed. The mean survival time was 6.9 months. Fourteen of 20 patients with NEC of the urinary bladder died of the disease and 19 of 24 patients with prostatic NEC died. The therapy for urinary bladder NEC was repeated transurethral resection and antiandrogen therapy was given for NEC of the prostate. Only one patient was treated with chemotherapy, which to the author's knowledge currently is the only treatment for NECs of the genitourinary tract.

CONCLUSIONS

Undifferentiated carcinomas of the urinary bladder and prostate should be analyzed not only by means of hematoxylin and eosin but also by immunohistochemical staining for Chr A and SNP to demonstrate a neuroendocrine origin. Because the prognosis of small cell NECs is very poor, pathologists should indicate in their final report the peculiarities of small cell NECs of the prostate and the urinary bladder with special emphasis on different therapeutic strategies.

Neuroendocrine expression in node positive prostate cancer: correlation with systemic progression and patient survival

PURPOSE

Neuroendocrine cells are ubiquitous but uncommon in benign and neoplastic prostate epithelium, and they are considered important for regulating cell growth and differentiation. The predictive value of neuroendocrine immunoreactivity for patient outcome after radical prostatectomy is uncertain. In this study we determined the expression of 2 important neuroendocrine markers, chromogranin and serotonin, in benign epithelium, primary prostate cancer and lymph node metastases, and correlated cellular expression with patient outcome.

MATERIALS AND METHODS

We studied 196 patients with node positive prostate adenocarcinoma who underwent bilateral pelvic lymphadenectomy and radical prostatectomy at Mayo Clinic between 1987 and 1992. Mean followup was 6.8 years (range 0.3 to 11). The cellular expression of chromogranin and serotonin in matched samples of benign tissue, primary prostate cancer and lymph node metastases from the same patients was evaluated by immunohistochemical staining using commercially available monoclonal antibodies. Results were correlated with patient age, pathological findings (Gleason score, DNA ploidy and cancer volume) and patient outcome, including clinical progression, cancer specific and all cause survival.

RESULTS

Chromogranin immunoreactivity was greater in benign prostatic epithelium and primary cancer cases (99% each) than in those of lymph node metastases (37.5%) (pairwise comparisons with metastases p <0.001). The mean incidence of immunoreactive cells in benign epithelium, primary cancer and metastases was 6% (median 5%), 6% (median 3%) and 2.2% (median 0%), respectively. Serotonin immunoreactivity was greatest in benign prostate epithelium cases (98.5%) with less in primary cancer (95%) and lymph node metastases (21.5%) (pairwise comparisons p <0.001). The mean incidence of immunoreactive cells in benign epithelium, primary cancer and metastases was 2.2% (median 3%), 2.4% (median 2%) and 0.4% (median 0%), respectively. Chromogranin expression was invariably greater than that of serotonin for all 3 diagnostic categories (p <0.0001). There was a marginally significant positive trend in the level of chromogranin expression in benign prostatic epithelium and systemic progression (p = 0.05) but no significant association with cancer specific or all cause survival (p >0.1). No significant association was observed of chromogranin expression in primary cancer or lymph node metastases with any patient outcomes (p >0.1). There was a significant association of the level of serotonin expression in benign prostatic epithelium with cancer specific survival (p = 0.03) but no significant association with systemic progression or all cause survival (p > 0.1). There were positive trends in the association of serotonin immunoreactivity in primary cancer with systemic progression (p = 0.09) and cancer specific survival (p = 0.05) but not with all cause survival (p >0.1). No significant association was observed of serotonin expression in lymph node metastases with any patient outcomes (p >0.1).

CONCLUSIONS

Benign prostatic epithelium and primary prostate cancer express a significantly greater number of chromogranin and serotonin immunoreactive cells than lymph node metastases, suggesting that decreased expression of neuroendocrine markers is involved in cancer progression. However, neuroendocrine expression was marginally useful for predicting the outcome in patients with node positive prostate cancer treated with radical prostatectomy.

Prostatic adenocarcinoma metastases mimicking small cell carcinoma on fine-needle aspiration

Prostate adenocarcinoma (PA) is known to metastasize widely to bone, lung, lymph nodes, and other sites. We have observed a rare, although distinctive, neuroendocrine (NE) cytomorphology of metastatic PA on fine-needle aspiration (FNA) that mimics small cell carcinoma (SCC). From a total of 117 cases, eight cases of metastatic PA diagnosed on FNA showed cytomorphologic features indistinguishable from SCC. All specimens were reviewed, along with immunoperoxidase (IPOX) studies using prostate specific (PSA, PSAP) and NE markers (synaptophysin, chromogranin, etc.). The patients ranged in age from 51-68 (mean age = 63). The PSA levels at the time of FNA ranged from <0.1 to 2,892 ng/ml (normal postprostatectomy <0.2 ng/ml). Sites of FNA included liver (two), soft tissue (five), and lymph node (one). FNA was performed from 11 mo to 6 yr after the initial diagnosis of the primary tumor. All primary PA were of high Gleason grade ranging from 7-9. None of the primary PA showed neuroendocrine morphology. Cytomorphologic characteristics observed on FNA included predominantly single cells with occasional sheets or loose cell aggregates. A predominant NE nuclear morphology was evident (i.e., hyperchromasia, fine dusty chromatin, inconspicuous nucleoli, nuclear molding, chromatinic crush artifact, karyorrhexis, mitoses, etc.), with none of the tumors displaying glandular formation. Taken together, these features gave these metastases a cytomorphology indistinguishable from SCC. IPOX studies revealed PSA-positivity (5/7), PSAP-positivity (4/7), and only focal NE markers positivity (3/6). Metastatic prostate carcinoma may rarely mimic a SCC (6.8% in this study). This often necessitates further patient workup to identify the primary source for the patient's metastasis, particularly if the patient has multiple lesions. An accurate diagnosis of these lesions as PA metastases is essential for effective, timely treatment and therapeutic design.

Prostate carcinoma with neuroendocrine differentiation: case report and literature review

Neuroendocrine differentiation in prostatic carcinomas generally confers a more aggressive clinical behavior and less favorable prognosis than usual prostatic carcinomas. In this manuscript, we report a case of a 58-year-old man with prostatic carcinoma who died 1 year after initial diagnosis. Autopsy showed a disseminated prostatic carcinoma with neuroendocrine differentiation. There were metastasis to the spleen, an organ infrequently involved by disseminated epithelial neoplasms. Neuroendocrine differentiation was demonstrated by immunohistochemical studies in the biopsy and autopsy material.

Histopathologic effects of three-dimensional conformal external beam radiation therapy on benign and malignant prostate tissues

We reviewed 137 prostate sextant needle biopsies from 137 patients obtained at a median of 35.7 months after three-dimensional conformal external beam radiation therapy (3DCRT). Thirty-one patients (23%) received 3 months of androgen deprivation therapy (ADT) before 3DCRT. We also retrospectively reviewed and assigned a combined Gleason score to the pre-3DCRT needle biopsies (97 patients) or transurethral resection of the prostate gland (1 patient). High-molecular-weight cytokeratin (34betaE12) and prostate-specific antigen (PSA) immunohistochemistry was performed in select cases. After 3DCRT, histopathologic changes in benign prostate gland consisted of glandular atrophy, cytologic atypia, and basal cell prominence. The benign glands showed intensely positive reactions with antibodies to high-molecular-weight cytokeratin (34betaE12) and negative to weakly positive reactions to PSA. Paneth cell-like change was seen in 44 (32%) of the biopsies, mucinous metaplasia in 29 (21%), luminal blue-tinged mucinous secretions in 14 (10%), and squamous metaplasia in 8 (6%). The changes in benign prostate tissues were similar between patients treated with ADT and 3DCRT and those treated with 3DCRT alone. After 3DCRT, we recognized two histologic patterns of prostate cancer: (1) prostate cancer showing radiation therapy (RT)-related changes characterized by PSA-positive/34betaE12-negative poorly formed glands or individual cells with abundant clear to finely granular cytoplasm, and (2) prostate cancer showing no apparent RT effect. High-grade prostatic intraepithelial neoplasia (PIN) was seen in 12 post-3DCRT biopsies (8.8%). The use of neoadjuvant ADT had a significant impact on the results of post-RT biopsy. Of the 31 patients treated with neoadjuvant ADT and 3DCRT, 3 (10%) had post-3DCRT biopsies showing prostate cancer without RT effect compared to 44 of 106 men (41%) treated with 3DCRT alone (p = 0.004). Compared to the Gleason score pre-RT, the Gleason score of cancers showing no RT effect was the same in 25 patients (71%), +/-1 point in 8 patients (23%), and +2 points in 2 patients (6%). The mean combined Gleason score post-RT was slightly, although significantly, higher than that pre-RT (7.29 +/- 0.71 versus 7.00 +/- 0.59, p = 0.01). Serum PSA at the time of post-3DCRT biopsy correlated with biopsy results. Prostate cancer without therapy effect was seen in only one of 43 patients (2%) with a serum PSA level < or = 1 ng/ml compared to 46 of 94 patients (49%) with a PSA level > 1 ng/ml (p = 0.0001). After 3DCRT, benign prostate glands show profound histopathologic changes and may be confused with prostate cancer. The effects of 3DCRT on prostate cancer are variable, with some cases showing profound therapy-related changes and others showing no apparent therapy effect.

Genitourinary small cell carcinoma: determination of clinical and therapeutic factors associated with survival

PURPOSE

We assessed the prognostic impact of genitourinary small cell carcinoma tumor and patient characteristics, and therapy.

MATERIALS AND METHODS

We retrospectively reviewed the records of 180 patients with genitourinary small cell carcinoma in which patient and tumor characteristics, therapy, followup duration and survival status had been documented. Patient age, sex, primary site, histological features, tumor size, stage, locoregional therapy, systemic chemotherapy and hormonal manipulations were analyzed for association with survival.

RESULTS

There were 106 cases of bladder, 60 prostatic, 8 renal and 6 ureteral small cell carcinoma. Median survival was 10.5 months overall, and 7 and 13 months for prostatic and bladder small cell carcinoma, respectively (p <0.0001 log rank analysis). In all cases metastatic disease at presentation (p <0.008, risk ratio 1.9) predicted poor survival on multivariate analysis. Radical surgery (p <0.0001, risk ratio 0.34) and cisplatin chemotherapy (p <0.0001, risk ratio 0.20) were the only factors that predicted improved survival on multivariate analysis. For prostatic small cell carcinoma primary surgical therapy (p <0.012, risk ratio 0.46) was the only parameter that predicted survival on univariate analysis. For bladder small cell carcinoma only cisplatin chemotherapy (p <0.0001, risk ratio 0.15) predicted survival on multivariate analysis.

CONCLUSIONS

Genitourinary small cell carcinoma has a poor prognosis, which is worse in prostatic than bladder disease. Patient and tumor characteristics were not determinants of survival when prostatic and bladder small cell carcinoma were analyzed individually. For prostatic disease only primary surgical therapy was associated with prolonged survival, while for bladder disease cisplatin chemotherapy was associated with a favorable prognosis. We recommend considering primary surgical therapy for prostatic and cisplatin based chemotherapy for bladder small cell carcinoma.

Prostatic marker-negative amphicrine carcinoma of the prostate

It has been shown that prostatic adenocarcinoma differentiation correlates with prostatic-specific marker and neuroendocrine expression; that is, the more undifferentiated the tumor, the less it expresses prostatic markers and the more neuroendocrine cells are found in it. Complete absence of prostatic markers together with marked neuroendocrine expression has been associated with small cell morphology. This report describes a case of a metastatic, prostatic marker-negative, non-small cell prostatic adenocarcinoma with a prominent neuroendocrine component. The architecturally well-organized luminal-exocrine cells appeared ultrastructurally undifferentiated, however, displaying an almost empty cytoplasm. This contrasted with the prostatic marker-positive control cases of prostatic carcinoma, which contained relatively numerous cytoplasmic vacuoles. The neuroendocrine cells could be identified by light microscopy as eosinophilic cells. The number of the latter cells was markedly increased in the metastatic foci compared with the primary tumor. Light microscopically and ultrastructurally, the eosinophilic cells in this case differed from the Paneth-like cells described in prostatic carcinoma in previous reports. This case provides support for the general concept of multidirectional differentiation in human epithelial cancers and in particular for the association of poor tumor differentiation with neuroendocrine expression in prostatic carcinoma. In addition, in contrast with previous reports describing absence of basement membrane in metastatic foci of prostatic carcinoma, in the current case well-formed basal laminae were identified.

Immunohistochemical localization of chromogranins A and B and secretogranin II in normal, hyperplastic and neoplastic prostate

Routinely processed normal, hyperplastic and neoplastic prostatic tissue was immunohistochemically investigated with antibodies against chromogranin A and B and secretogranin II. In normal and hyperplastic prostates all three peptides were immunolocalized in scattered neuroendocrine cells situated within the glandular epithelium. In 17 prostatic carcinomas with pronounced neuroendocrine differentiation and in a case of prostatic carcinoid, chromogranin B was the major component whereas chromogranin A and secretogranin II were virtually absent in poorly differentiated (grade III) tumours. Neuroendocrine differentiation in prostatic cancer is most likely to be associated with a poor clinical outcome; thus, chromogranin B appears to be a useful marker in the histopathological diagnosis of these neoplasms.

Paneth cell-like change in prostatic adenocarcinoma represents neuroendocrine differentiation: report of 30 cases

Paneth cell-like change (PCLC) of the prostatic epithelium is considered to be a distinct form of neuroendocrine differentiation characterized by isolated cells or small groups of cells with prominent eosinophilic cytoplasmic granules. We evaluated 300 serially sectioned radical prostatectomy specimens from patients with prostatic adenocarcinoma who had not received prior adjuvant therapy (pathologic stages T2NOMO [177 patients], T3NOMO [100 patients], and TxN1MO [23 patients]). Paneth cell-like change was identified in 30 cases (10%), ranging from 1 to 20 high-power fields/positive case (mean, 4.1 high-power fields/case). There was no correlation of PCLC with prostate volume, prostate weight, Gleason grade, nuclear grade, lymph node metastases, serum prostate-specific antigen levels, cancer volume, area or presence of capsular perforation, seminal vesicle invasion, or glandular mucin (all P > .05), although a positive correlation was seen with cribriform pattern (r = 0.50, P = .0015). Immunohistochemistry revealed cytoplasmic immunoreactivity within cells of PCLC for chromogranin (seven of seven cases), neuron-specific enolase (seven of seven cases), serotonin (six of seven cases), prostate-specific antigen (five of seven cases), and prostatic acid phosphatase (four of seven cases); lysozyme was negative (seven cases). Our findings indicate that PCLC is more common than previously reported, but that it is not associated with tumor grade, serum PSA levels, or pathologic stage. This study also shows that PCLC represents neuroendocrine differentiation, suggesting that the term "Paneth cell-like change" be deleted from the pathologist's lexicon in relation to prostatic adenocarcinoma; a more appropriate term might be "neuroendocrine cells with large eosinophilic granules."