Clear cell adenocarcinoma of the bladder and urethra

Comprehensive genomic profiling of histologic subtypes of urethral carcinomas

BACKGROUND

Carcinoma of the urethra (UrthCa) is an uncommon Genitourinary (GU) malignancy that can progress to advanced metastatic disease.

METHODS

One hundred twenty-seven metastatic UrthCa underwent hybrid capture-based comprehensive genomic profiling to evaluate all classes of genomic alterations (GA). Tumor mutational burden was determined on up to 1.1 Mbp of sequenced DNA, and microsatellite instability was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3).

RESULTS

Forty-nine (39%) urothelial (UrthUC), 31 (24%) squamous (UrthSCC), 24 (19%) adenocarcinomas NOS (UrthAC), and 12 (9%) clear cell (UrthCC) were evaluated. UrthUC and UrthSCC are more common in men; UrthAC and UrthCC are more common in women. Ages were similar in all 4 groups. GA in PIK3CA were the most frequent potentially targetable GA; mTOR pathway GA in PTEN were also identified. GA in other potentially targetable genes were also identified including ERBB2 (6% in UrthUC, 3% in UrthSCC, and 12% in UrthAC), FGFR1-3 (3% in UrthSCC), BRAF (3% in UrthAC), PTCH1 (8% in UrthCC), and MET (8% in UrthCC). Possibly reflecting their higher GA/tumor status, potential for immunotherapy benefit associated with higher tumor mutational burden and PD-L1 staining levels were seen in UrthUC and UrthSCC compared to UrthAC and UrthCC. Microsatellite instability high status was absent throughout.

CONCLUSIONS

Comprehensive genomic profiling reveals GA that may be predictive of both targeted and immunotherapy benefit in patients with advanced UrthCa and that could potentially be used in future adjuvant, neoadjuvant, and metastatic disease trials.

Personalized chemotherapy in clear cell adenocarcinoma of the urethra: A case report

BACKGROUND

Clear cell adenocarcinoma of the urethra is a rare type of aggressive cancer with a poor prognosis. Clear cell carcinoma of the urethra represents less than 0.02% of all malignancies in women. Adenocarcinomas account for 10% of female urethral carcinomas, of which 40% are the clear cell variant. Determining the presence or absence of certain mutations through genetic testing may predict whether a patient with cancer may benefit from a particular chemotherapy regimen.

CASE SUMMARY

A 40-year-old woman presented with a 3-year history of slow urinary flow and a 3-mo history of urinary urgency and frequency as well as gross hematuria. An abdominal and pelvic computed tomography scan demonstrated enlarged lymph nodes in the abdomen and pelvis. A biopsy of a left inguinal lymph node microscopically confirmed a metastatic adenocarcinoma of the urethra. Specialized genetic testing determined personalized chemotherapy. She was treated successfully with a non-platinum-based chemotherapy consisting of paclitaxel and bevacizumab. Following 3 cycles of paclitaxel and bevacizumab, she attained significant clinical improvement, and response by FDG-Positron emission tomography (PET) imaging showed a definite improvement in size and metabolic activity. She achieved complete response after 6 cycles of therapy by PET scan. The patient concluded 11 cycles of paclitaxel and bevacizumab, and a subsequent PET scan confirmed progression of metastatic disease. The patient was then treated with two cycles of doxorubicin after which a PET scan revealed a mixed response to the treatment.

CONCLUSION

We report the first case of a patient with metastatic clear cell adenocarcinoma of the urethra who underwent personalized chemotherapy after testing for cancer gene alterations. Our unique case represents the safe and effective use of non-platinum-based chemotherapy in clear cell adenocarcinoma of the urethra.

Histology and immunohistochemistry of clear cell adenocarcinoma of the urethra: histogenesis and diagnostic problems

Clear cell adenocarcinoma (CCAC) of the urethra is a rare neoplasm, morphologically identical to its homologue arising in the female genital tract. The histogenesis of this neoplasm is uncertain. We present clinical, histopathologic, and immunohistochemical findings of four CCAC of the urethra and discuss the histogenesis and difficulties in diagnosis and differential diagnosis. CCAC of the urethra occurred in females (4/4). Two neoplasms were identified in urethral diverticulum; one of the two cases, in close proximity to a nephrogenic adenoma. CCAC exhibited tubulocystic, papillary, and diffuse/solid growth patterns. The neoplastic cells were cuboidal or columnar with eosinophilic or clear cytoplasm, and nuclear pleomorphism of at least moderate degree. Hobnail features and tumor necrosis were also observed. CCAC expressed p53 (4/4), AMACR (3/4), vimentin (3/4), PAX8 (2/4), CK7 (2/4), cytokeratin 34betaE12 (2/4), RCC (1/4), and CK20 (1/4) and were negative for PSA, WT1, ER, CA 125, uroplakin III, p16, and p63. The immunohistochemical profile supports a possible renal tubular cell differentiation/mesonephric origin for some urethral CCAC. Nephrogenic adenoma and metastatic clear cell carcinoma are the most important differential diagnostic considerations. Multicenter studies on more cases may improve our understanding of this malignancy.