Primary small cell neuroendocrine carcinoma of the female urethra

Emerging Insights in Small-Cell Carcinoma of the Genitourinary Tract: From Diagnosis to Novel Therapeutic Horizons

Small-cell carcinomas (SCCs) of the genitourinary (GU) tract are rare malignancies with high metastatic potential. The most common primary sites are the bladder and prostate, but case reports of primary SCC of the kidney, ureter, and urethra also exist. The majority of patients present with gross hematuria, irritative or obstructive urinary symptoms, and symptoms of locoregionally advanced or metastatic disease at initial presentation. SCC of the bladder presents with nodal or metastatic involvement in the majority of cases and requires the use of platinum-based chemotherapy in combination with surgery and/or radiation. SCC of the prostate is most commonly seen in the metastatic castrate-resistant setting, and aggressive variant disease presents with a greater propensity for visceral metastases, osteolytic lesions, and relatively low serum prostate-specific antigen for volume of disease burden. Multiple retrospective and prospective randomized studies support the use of a multimodal approach combining platinum-based systemic therapy regimens with radiation and/or surgery for localized disease. This evidence-based strategy is reflected in multiple consensus guidelines. Emerging data suggest that small-cell bladder and prostate cancers transdifferentiate from a common progenitor of conventional urothelial bladder carcinoma and prostatic acinar adenocarcinoma, respectively. Areas of active basic research include efforts to identify the key genetic and epigenetic drivers involved in the emergence of small cell cancers to exploit them for novel therapies. Here, we review these efforts, discuss diagnosis and currently supported management strategies, and summarize ongoing clinical trials evaluating novel therapies to treat this rare, aggressive GU cancer.

A case of neuroendocrine tumor at the external urethral meatus after total cystectomy

Introduction

The histological types of urethral cancer are mainly squamous cell or transitional cell carcinoma. Neuroendocrine tumor is extremely a rare type of urethral cancer.

Case presentation

A 72-year-old man visited with an erythema at the external urethral meatus. After 3 months, a 1-cm reddish solid tumor was found on the external urethral meatus. He had a history of bladder cancer (pTa with carcinoma in situ), including the prostatic urethra, and underwent radical cystectomy with urethrectomy and ileal conduit construction 11 years ago. After 3 months, a 1-cm reddish solid tumor was found on the external urethral meatus. The pathological diagnosis was a neuroendocrine tumor. Partial penectomy was performed.

Conclusion

Small cell neuroendocrine tumor could occur on urethral remnant after radical cystectomy with urethrectomy for urothelial cancer. Inspection of the penis and urethral meatus is important during regular follow-up of patients after radical cystectomy.

Recurrent urethral tumor with neuroendocrine differentiation in a female patient after radical cystectomy for bladder cancer

Introduction

Urethral recurrence after radical cystectomy in female patients with bladder cancer is relatively uncommon. Recurrent bladder tumors with neuroendocrine differentiation are extremely rare.

Case presentation

A 71-year-old female patient who underwent radical cystectomy for bladder cancer presented with vaginal bleeding 19 months postoperatively. She was diagnosed with bladder cancer urethral recurrence. Urethral tumor en-bloc resection with the anterior vaginal wall was performed by combining abdominal and vaginal approaches. Pathological examination revealed a recurrent tumor of urothelial bladder cancer containing small-cell carcinoma components.

Conclusion

This case is the first report of a recurrent tumor with small-cell carcinoma in the female urethra after radical cystectomy for pure urothelial carcinoma.

Reprint of: Female Urethral Carcinoma: A contemporary review of the clinicopathologic features, with emphasis on the histo-anatomic landmarks and potential staging issues

Primary female urethral carcinoma (PUC-F) accounts for less than 1% of all genitourinary malignancies and comprises a histologically diverse group of tumors that are usually associated with poor prognosis. The carcinomas documented at this site include adenocarcinoma (clear cell adenocarcinoma, columnar cell carcinoma, and Skene gland adenocarcinoma), urothelial carcinoma (UCa), and squamous cell carcinoma (SCC). Recent studies have shown adenocarcinomas to be the most common type of primary urethral carcinoma in females. As most of the urethral carcinomas morphologically resemble carcinomas arising from surrounding pelvic organs or metastases, these should be ruled out before making the diagnosis of PUC-F. These tumors are currently staged according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system. However, the AJCC system has limitations, including the staging of tumors involving the anterior wall of the urethra. Staging systems like the recently proposed histology-based female urethral carcinoma staging system (UCS) takes into account the unique histological landmarks of the female urethra to better stratify pT2 and pT3 tumors into prognostic groups, that correlate with clinical outcomes including recurrence rates, disease-specific survival and overall survival. Further larger multi-institutional cohorts are however required to validate the results of this staging system. There is very limited information regarding the molecular profiling of PUC-F. Thirty-one percent of clear cell adenocarcinomas have been reported to show PIK3CA alterations, whereas 15% of adenocarcinomas show PTEN mutations. Higher tumor mutational burden and PD-L1 staining have been reported in UCa and SCC. Although multimodality treatment is usually recommended in locally advanced and metastatic disease, the role of immunotherapy and targeted therapy is promising in select PUC-F cases.

Imaging of neuroendocrine neoplasms of the male GU tract

Male genitourinary neuroendocrine neoplasms (GU-NENs) are rare, without any definite imaging characteristics. The WHO classified neuroendocrine neoplasms in the 2016 classification of the tumors of the urinary tract and genital organs along with other GU tumors; however, no pathologic grading system is available as published for gastroenteropancreatic neuroendocrine neoplasms. Often a multimodality approach using cross-sectional imaging techniques, such as molecular imaging and histopathology are implemented to arrive at the diagnosis. This article provides a review of the pathology and imaging features of the male GU-NENs.

Female urethral carcinoma: a contemporary review of the clinicopathologic features, with emphasis on the histoanatomic landmarks and potential staging issues

Primary female urethral carcinoma (PUC-F) accounts for less than 1% of all genitourinary malignancies and comprises a histologically diverse group of tumors that are usually associated with poor prognosis. The carcinomas documented at this site include adenocarcinoma (clear cell adenocarcinoma, columnar cell carcinoma, and Skene gland adenocarcinoma), urothelial carcinoma (UCa), and squamous cell carcinoma (SCC). Recent studies have shown adenocarcinomas to be the most common type of primary urethral carcinoma in females. As most of the urethral carcinomas morphologically resemble carcinomas arising from surrounding pelvic organs or metastases, these should be ruled out before making the diagnosis of PUC-F. These tumors are currently staged according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system. However, the AJCC system has limitations, including the staging of tumors involving the anterior wall of the urethra. Staging systems like the recently proposed histology-based female urethral carcinoma staging system (UCS) takes into account the unique histological landmarks of the female urethra to better stratify pT2 and pT3 tumors into prognostic groups, that correlate with clinical outcomes including recurrence rates, disease-specific and overall survival. Further larger multi-institutional cohorts are however required to validate the results of this staging system. There is very limited information regarding the molecular profiling of PUC-F. Thirty-one percent of clear cell adenocarcinomas have been reported to show PIK3CA alterations, whereas 15% of adenocarcinomas show PTEN mutations. Higher tumor mutational burden and PD-L1 staining have been reported in UCa and SCC. Although multimodality treatment is usually recommended in locally advanced and metastatic disease, the role of immunotherapy and targeted therapy is promising in select PUC-F cases.

Neuroendocrine Neoplasms of the Female Genitourinary Tract: A Comprehensive Overview

Simple Summary

Primary neuroendocrine neoplasms (NENs) are a rare, heterogeneous group of tumors that include well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinoma, and paraganglioma. NENs in the urinary tract are observed in <0.05% of individuals, in whom the bladder is the most common site. In this review, we described the epidemiology, pathogenesis, imaging, staging, and management of the genitourinary NENs.

Abstract

Primary neuroendocrine neoplasms are a rare heterogeneous group of tumors that include well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinoma, and paraganglioma. An extensive literature search was used to compile the data regarding epidemiology, pathogenesis, imaging features, and management of the urinary system NENs. We also included the updated staging of the NENs at various locations of the urinary system.

Primary Small Cell Neuroendocrine Tumor Within a Urethral Diverticulum

BACKGROUND

Primary small cell neuroendocrine carcinoma of the urinary tract is a very rare cancer, accounting for fewer than 0.5% of urinary tract tumors. These are aggressive neoplasms with high rates of metastases. Urethral diverticula can be found in up to 6% of women.

CASE

A 31-year-old woman presented with a clear vaginal discharge and an anterior vaginal wall mass that was thought to be a recurrent cyst. After surgical dissection, she was noted to have a urethral diverticulum with a solid nodule at the base. Final pathology showed a high-grade small cell neuroendocrine carcinoma.

CONCLUSION

Malignancy in a urethral diverticulum can occur in young patients. Clinicians should be aware of this possibility when choosing to manage urethral lesions expectantly.

Primary Mixed Glandular-endocrine Tumor of the Male Proximal Urethra: A Case Report

Primary urethral carcinoma is much more common in women than in men due to its association with urethritis. A 65-year-old man presented with a 10-month history of penile induration, obstructive voiding symptoms and hematuria. Urethrocystoscopy showed a solitary mass in the proximal urethra and no bladder involvement. It was performed penectomy without bladder neck excision and regional staging lymphadenectomy of the obturator lymph nodes. Pathological diagnosis revealed adenosquamous cell carcinoma with squamous and glandular components. We described a case of primary mixed glandular-endocrine tumor of the male proximal urethra consisting of adenosquamous cell carcinoma with squamous and neuroendocrine components.

Small cell carcinoma arising from the bulbar urethra: a case report and literature review

Primary neuroendocrine carcinomas of the genitourinary tract are rare and aggressive tumors carrying a bad prognosis. With squamous cell and transitional cell carcinoma being the most commonly reported urethral malignancies, primary small cell carcinoma (SCC) of the urethra is extremely rare. To date, only 5 cases have been reported in the literature. We present the first case of primary SCC occurring in the bulbar urethra in an 89-year-old male. We discuss the clinical, histological and immunohistochemical features of SCC of the urethra. Furthermore, we summarize the available literature and discuss the possible treatment options for this rare yet aggressive neoplasm.