Variants and unusual patterns of prostate cancer: clinicopathologic and differential diagnostic considerations

Case report: Squamous cell carcinoma of the prostate-a clinicopathological and genomic sequencing-based investigation

Squamous differentiation of prostate cancer, which accounts for less than 1% of all cases, is typically associated with androgen deprivation treatment (ADT) or radiotherapy. This entity is aggressive and exhibits poor prognosis due to limited response to traditional treatment. However, the underlying molecular mechanisms and etiology are not fully understood. Previous findings suggest that squamous cell differentiation may potentially arise from prostate adenocarcinoma (AC), but further validation is required to confirm this hypothesis. This paper presents a case of advanced prostate cancer with a combined histologic pattern, including keratinizing SCC and AC. The study utilized whole-exome sequencing (WES) data to analyze both subtypes and identified a significant overlap in driver gene mutations between them. This suggests that the two components shared a common origin of clones. These findings emphasize the importance of personalized clinical management for prostate SCC, and specific molecular findings can help optimize treatment strategies.

Variability of radiotherapy volume delineation: PSMA PET/MRI and MRI based clinical target volume and lymph node target volume for high-risk prostate cancer

PURPOSE

A comparative retrospective study to assess the impact of PSMA Ligand PET/MRI ([68 Ga]-Ga-PSMA-11 and [18F]-F-PSMA-1007 PET/MRI) as a new method of target delineation compared to conventional imaging on whole-pelvis radiotherapy for high-risk prostate cancer (PCa).

PATIENTS AND METHODS

Forty-nine patients with primary high-risk PCa completed the whole-pelvis radiotherapy plan based on PSMA PET/MRI and MRI. The primary endpoint compared the size and overlap of clinical target volume (CTV) and nodal gross tumour volume (GTVn) based on PSMA PET/MRI and MRI. The diagnostic performance of two methods for pelvic lymph node metastasis (PLNM) was evaluated.

RESULTS

In the radiotherapy planning for high-risk PCa patients, there was a significant correlation between MRI-CTV and PET/MRI-CTV (P = 0.005), as well as between MRI-GTVn and PET/MRI-GTVn (P < 0.001). There are non-significant differences in the CTV and GTVn based on MRI and PET/MRI images (P = 0.660, P = 0.650, respectively). The conformity index (CI), lesion coverage factor (LCF) and Dice similarity coefficient (DSC) of CTVs were 0.999, 0.953 and 0.954. The CI, LCF and DSC of GTVns were 0.927, 0.284, and 0.32. Based on pathological lymph node analysis of 463 lymph nodes from 37 patients, the sensitivity, specificity of PET/MRI in the diagnosis of PLNM were 77.78% and 99.76%, respectively, which were higher than those of MRI (P = 0.011). Eight high-risk PCa patients who finished PSMA PET/MRI changed their N or M stage.

CONCLUSION

The CTV delineated based on PET/MRI and MRI differ little. The GTVn delineated based on PET/MRI encompasses metastatic pelvic lymph nodes more accurately than MRI and avoids covering pelvic lymph nodes without metastasis. We emphasize the utility of PET/MRI fusion images in GTVn delineation in whole pelvic radiotherapy for PCa. The use of PSMA PET/MRI aids in the realization of more individual and precise radiotherapy for PCa.

Neoadjuvant Hormonal Therapy for Prostate Cancer: Morphologic Features and Predictive Parameters of Therapy Response

The primary goals of neoadjuvant hormonal therapy (NHT) in prostate cancer (PCa) are to reduce the size of the tumor, lower positive surgical margin rate, attempt to reach pathologic remission, and improve survival. Although NHT has not been recommended by the National Comprehensive Cancer Network as a primary treatment option for patients with localized PCa, NHT is increasingly used in clinical trials for locally advanced PCa. More importantly, with the development of novel androgen signaling inhibitors, such as abiraterone and enzalutamide, there has been renewed interests in revisiting the role of such treatment in the neoadjuvant setting. Following NHT, the PCa tissues shows characteristic morphologic alterations. Of note, the collapse of malignant glands most likely leads to an artificial increase of Gleason score in the residual disease. Communicating these changes to the clinician in a way that can help assess the tumor's response poses a challenge for pathologists. In addition, little is known of morphologic features and predictive makers both in pretreated and posttreated specimens that can be of value in predicting tumor response to NHT. In the current review, we summarize the morphologic changes associated with neoadjuvant-treated PCa, focusing on the predictive value of pathologic parameters to therapy response. We also describe the evaluation system in the stratification of pathologic response to NHT in PCa management.

Case 297: Mucinous Adenocarcinoma of the Prostate

History A 70-year-old man was referred to our institution with chronic obstructive urinary symptoms and constipation for 2 years before admission. His medical history was unremarkable. Outside laboratory tests revealed an elevated serum prostate-specific antigen level (21.7 ng/mL [normal range, 0.00-4.00 ng/mL]), and urinalysis results were negative. He was admitted for evaluation of possible prostate cancer. The patient reported no specific symptoms of infection and denied fever, dysuria, hematuria, and abdominal pain. He had no family history of prostate cancer. On physical examination, he was afebrile, and the digital rectal examination was not painful. These findings were evidence of an enlarged prostate and a hard multilobulated mass, which was palpable bilaterally. The urologic team performed MRI of the prostate.

Sox2 is necessary for androgen ablation-induced neuroendocrine differentiation from Pten null Sca-1+ prostate luminal cells

Prostate adenocarcinoma undergoes neuroendocrine differentiation to acquire resistance toward anti-hormonal therapies. The underlying mechanisms have been investigated extensively, among which Sox2 has been shown to play a critical role. However, genetic evidence in mouse models for prostate cancer to support the crucial role of Sox2 is missing. The adult mouse prostate luminal cells contain both castration-resistant Sox2-expressing Sca-1⁺ cells and castration-responsive Sca-1⁻ cells. We show that both types of the luminal cell are susceptible to oncogenic transformation induced by loss of function of the tumor suppressor Pten. The tumors derived from the Sca-1⁺ cells are predisposed to castration resistance and castration-induced neuroendocrine differentiation. Genetic ablation of Sox2 suppresses neuroendocrine differentiation but does not impact the castration resistant property. This study provides direct genetic evidence that Sox2 is necessary for androgen ablation-induced neuroendocrine differentiation of Pten null prostate adenocarcinoma, corroborates that the lineage status of the prostate cancer cells is a determinant for its propensity to exhibit lineage plasticity, and supports that the intrinsic features of cell-of-origin for prostate cancers can dictate their clinical behaviors.

De novo induction of lineage plasticity from human prostate luminal epithelial cells by activated AKT1 and c-Myc

Neuroendocrine prostate cancer (NEPC) is an aggressive variant of prostate cancer that either develops de novo or arises from prostate adenocarcinoma as a result of treatment resistance. Although the prostate basal cells have been shown to directly generate tumor cells with neuroendocrine features when transduced with oncogenic signaling, the identity of the cell-of-origin for de novo NEPC remains unclear. We show that the TACSTD2^high human prostate luminal epithelia cells highly express SOX2 and are relatively enriched in the transition zone prostate. Both TACSTD2^high and TACSTD2^low luminal cells transduced by activated AKT and c-Myc can form organoids containing versatile clinically relevant tumor cell lineages with regard to the expression of AR and the neuroendocrine cell markers Synaptophysin and Chromogranin A. Tumor organoid cells derived from the TACSTD2^high luminal cells are more predisposed to neuroendocrine differentiation along passaging and are relatively more castration-resistant. Knocking down TACSTD2 and SOX2 both attenuate neuroendocrine differentiation of tumor organoid cells. This study demonstrates de novo neuroendocrine differentiation of the human prostate luminal epithelial cells induced by caAKT and c-Myc and reveals an impact of cellular status on initiation of lineage plasticity.

Metastatic squamous cell carcinoma transformed from prostatic adenocarcinoma following androgen deprivation therapy: A case report with clinicopathologic and molecular findings

Squamous cell carcinoma (SCC) of the prostate is a rare and clinically aggressive entity that may arise de novo or through transformation of prostatic adenocarcinoma, typically following hormonal or radiation therapy. Confirmation of prostatic origin, especially when evaluating a metastatic focus, often requires correlation with clinical and imaging findings, as the morphologic and immunohistochemical features of SCC are not organ-specific. Comprehensive genomic profiling (CGP) may provide additional information useful for confirming the primary site and for identifying potential targeted therapy options. CGP data may also contribute to our understanding of the molecular basis of squamous differentiation in prostatic malignancies. However, these data are limited, and to our knowledge, there are only three previously published cases of prostatic SCC with reported CGP findings. Herein, we report a case of metastatic keratinizing SCC diagnosed by core needle biopsy in a 68-year-old man with a history of prostatic adenocarcinoma status post radical prostatectomy and androgen deprivation therapy (ADT). NKX3.1 immunohistochemistry was negative. CGP was performed, and a TMPRSS2-ERG fusion, among other genetic alterations, was detected, supporting a diagnosis of metastatic SCC transformed from prostatic adenocarcinoma following ADT. This case supports the use of CGP or other molecular techniques not only to query potential targeted therapy options but also to refine the diagnosis and confirm the primary site of disease in cases with non-specific morphologic and immunophenotypic features, such as SCC.

Metastatic castration resistant prostate cancer with squamous cell, small cell, and sarcomatoid elements-a clinicopathologic and genomic sequencing-based discussion

Histologic variants are uncommon but well reported amongst cases of prostatic adenocarcinoma, including those in the setting of hormonal and/or chemoradiation therapy and castration resistance. However, the spectrum of morphologic phenotypes and molecular alterations present in such histologic variants are still incompletely understood. Herein, we describe a case of metastatic prostatic adenocarcinoma with hormonal and chemoradiation therapy-associated differentiation, displaying a combination of squamous cell, small cell, and sarcomatoid elements. The morphologic, immunohistochemical, and molecular observations are discussed with attention given to the gene alterations present, including in TP53, NF1, AR, PTEN, and RB1. Finally, we will compare our findings with those observed in uncommonly reported similar cases so as to detail the molecular underpinnings of such processes which may carry therapeutic implications.

[Pathological assessment of prostate cancer. New problems]

INTRODUCTION

Currently, the diagnosis and treatment of prostate cancer requires the pathologist to adopt a fresh approach to the interpretation of biopsies in order to provide the data required for the new forms of therapy.

DISCUSSION

The new evaluation criteria of the Gleason system are explained, with the redefinition of histological patterns and degree of malignancy, the incorporation of the so-called prognostic groups and the assessment of the tumour mass.

CONCLUSIONS

Updating of histopathological information helps to improve patient management, especially in cases of tumour confined to the prostate, given the possibility of local therapy.

TGFβ signaling limits lineage plasticity in prostate cancer

Although treatment options for localized prostate cancer (CaP) are initially effective, the five-year survival for metastatic CaP is below 30%. Mutation or deletion of the PTEN tumor suppressor is a frequent event in metastatic CaP, and inactivation of the transforming growth factor (TGF) ß signaling pathway is associated with more advanced disease. We previously demonstrated that mouse models of CaP based on inactivation of Pten and the TGFß type II receptor (Tgfbr2) rapidly become invasive and metastatic. Here we show that mouse prostate tumors lacking Pten and Tgfbr2 have higher expression of stem cell markers and genes indicative of basal epithelial cells, and that basal cell proliferation is increased compared to Pten mutants. To better model the primarily luminal phenotype of human CaP we mutated Pten and Tgfbr2 specifically in luminal cells, and found that these tumors also progress to invasive and metastatic cancer. Accompanying the transition to invasive cancer we observed de-differentiation of luminal tumor cells to an intermediate cell type with both basal and luminal markers, as well as differentiation to basal cells. Proliferation rates in these de-differentiated cells were lower than in either basal or luminal cells. However, de-differentiated cells account for the majority of cells in micro-metastases consistent with a preferential contribution to metastasis. We suggest that active TGFß signaling limits lineage plasticity in prostate luminal cells, and that de-differentiation of luminal tumor cells can drive progression to metastatic disease.

Treatment effects in prostate cancer

Nonsurgical treatments for prostate cancer include androgen-deprivation therapy (ADT), radiation therapy (RT), ablative therapies, chemotherapy, and newly emerging immunotherapies. These approaches can be used alone or in combination depending on the clinical scenario. ADT is typically reserved for high-risk locally or systemically advanced disease that is not amenable to curative surgery. Radiation therapy can be used instead of surgery as primary therapy with curative intent for low-intermediate-risk disease as well as for control of locally advanced disease not suitable for surgery. Ablative therapies can be used as primary therapy for low-intermediate-risk disease or as salvage therapy for clinically localized disease where RT has failed. Chemotherapy and immune-based therapies are currently used for androgen-independent disease, although the indications for these approaches may well change as new data from clinical trials accrue. Pathologists should be able to recognize tissue changes associated with these treatments to provide information that will optimize patient management. This is particularly true in situations where clinical history of recent or remote nonsurgical treatment is not provided with the specimen. In the absence of this information, pathologists encountering the features described herein are encouraged to review patient records or communicate directly with clinical colleagues to determine how a given patient was treated and when.

Solitary Spinal Epidural Metastasis from Prostatic Small Cell Carcinoma

Solitary, spinal epidural metastasis (SEM) that is not related to vertebral metastasis is very rare. And solitary SEM from prostatic cancer is rarely found in previously published reports. However, it is clinically significant due to the possibility of neurologic dysfunction, and it can be assessed by MRI. In this report, we show a case of solitary SEM arising from prostatic small cell carcinoma detected by MRI.

Intraductal Carcinoma of the Prostate: Morphologic Features, Differential Diagnoses, Significance, and Reporting Practices

The differential diagnosis for atypical cribriform lesions of the prostate has become increasingly complex and includes intraductal carcinoma of the prostate, high-grade prostatic intraepithelial neoplasia, and atypical intraductal proliferations. In this review, we summarize the morphologic and molecular features and significance of intraductal carcinoma of the prostate. We also summarize our institution's strategy for reporting and treatment recommendations for intraductal carcinoma of the prostate.

Models of neuroendocrine prostate cancer

Prostate cancer remains the second leading cause of cancer death in men in the USA and most western countries. Prostatic acinar adenocarcinoma is the most commonly diagnosed form of prostate cancer. Small-cell neuroendocrine carcinoma is less frequently identified at the time of initial diagnosis, but this highly aggressive form of prostate cancer is increasingly observed in patients who have failed first- and second-line hormone therapy. Thus, developing and exploring models of neuroendocrine prostate cancer (NePC) are of increasing importance. This review examines the relevant xenograft tumor and genetically engineered mouse models of NePC, with the aim of addressing salient features and clinical relevance.

HF, Paschal BM, Wotton D. Prostate cancer induced by loss of Apc is restrained by TGFβ signaling

Recent work with mouse models of prostate cancer (CaP) has shown that inactivation of TGFβ signaling in prostate epithelium can cooperate with deletion of the Pten tumor suppressor to drive locally aggressive cancer and metastatic disease. Here, we show that inactivating the TGFβ pathway by deleting the gene encoding the TGFβ type II receptor (Tgfbr2) in combination with a deletion of the Apc tumor suppressor gene specifically in mouse prostate epithelium, results in the rapid onset of invasive CaP. Micro-metastases were observed in the lymph nodes and lungs of a proportion of the double mutant mice, whereas no metastases were observed in Apc single mutant mice. Prostate-specific Apc;Tgfbr2 mutants had a lower frequency of metastasis and survived significantly longer than Pten;Tgfbr2 double mutants. However, all Apc;Tgfbr2 mutants developed invasive cancer by 30 weeks of age, whereas invasive cancer was rarely observed in Apc single mutant animals, even by one year of age. Further comparison of the Pten and Apc models of CaP revealed additional differences, including adenosquamous carcinoma in the Apc;Tgfbr2 mutants that was not seen in the Pten model, and a lack of robust induction of the TGFβ pathway in Apc null prostate. In addition to causing high-grade prostate intra-epithelial neoplasia (HGPIN), deletion of either Pten or Apc induced senescence in affected prostate ducts, and this restraint was overcome by loss of Tgfbr2. In summary, this work demonstrates that TGFβ signaling restrains the progression of CaP induced by different tumor suppressor mutations, suggesting that TGFβ signaling exerts a general tumor suppressive effect in prostate.

Expression of CD7, CD20 and CDX-2 in a secondary signet-ring cell tumor of the prostate: a case report

As is well-known, signet ring cell carcinoma (SRCC) rarely appears as a histological finding in the prostatic tissue. Nevertheless, a differentiation should be made between a primary tumor and a metastatic disease. We describe the case of a 52-year-old man with lower urinary tract symptoms, serum total PSA of 0.2 ng/ml, elevated serum CEA and CA19-9 levels. Two years prior to presentation, he underwent total gastrectomy with histological findings indicating poor differentiated adenocarcinoma with signet-ring cell. A palpable nodule was found on digital rectal examination and for this reason he underwent 12-core transperineal prostate biopsy with a diagnosis of poor differentiated adenocarcinoma with signet-ring cell and adipose tissue infiltration. Immunohistochemical examinations revealed positivity for PAS, CK7 and CDX-2, focal positivity for CK20 and negativity for PSA and PSAP. The diagnosis of a prostatic secondary SRCC was possible given the positivity to CK7, CDX-2, focal positivity to CK20 and negativity to PSA.