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CASE REPORT
Year : 2021 | Volume
: 13
| Issue : 4 | Page : 434-437
Primary clear cell adenocarcinoma of prostate: A diagnostic challenge
Che-Wei Chang1, Hsin-Ling Yin2, Ching-Chia Li3
1 Department of Urology, Kaohsiung Municipal Siaogang Hospital; Department of Urology, Kaohsiung Medical University Hospital; Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan
2 Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
3 Department of Urology, Kaohsiung Medical University Hospital; Department of Urology, School of Medicine; Department of Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
Correspondence Address:
Dr. Ching-Chia Li
Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung
Taiwan
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DOI: 10.4103/UA.UA_187_20
Abstract
Clear cell adenocarcinoma (CCA) rarely occurs in men, not to mention in prostate. We reported a 44-year-old male patient who suffered from recurrent dysuria and frequency for 6 months. Transurethral resection of the prostate was performed to relieve bladder outlet obstruction. However, CCA of the prostate was confirmed through pathological examination. A thorough checkup was performed to distinguish it from metastatic clear cell carcinoma from other primary origins. Currently, no consensus for the treatment of CCA of the prostate has been reached. After discussing with the patient, he decided to receive immunotherapy with pembrolizumab. Herein, we reported this rare case of CCA in the prostate.
Keywords: Clear cell adenocarcinoma, immunotherapy, prostate
Introduction 
Clear cell adenocarcinoma (CCA) usually presents in female genital tracts with a poor prognosis. In men, CCA is an extremely rare tumor that resembles prostate adenocarcinoma, metastatic clear cell renal cell carcinoma (CCRCC), and renal-type clear cell carcinoma (RTCCC). Typical complaints include urinary retention, gross hematuria, and urinary tract infection. Herein, we presented a rare case of CCA in the prostate which was the second documented case in the English literature.
Case Report A 44-year-old man without any underlying diseases suffered from dysuria and frequency for several months. He first went to a local hospital for help where pelvic computed tomography, transurethral resection of the prostate, and cystostomy were done. The pelvic computed tomography revealed an enlarged prostate with heterogeneous densities and abscess formation [Figure 1]. He was then referred to our hospital for a second opinion. In the outpatient department, digital rectal examination showed marked enlargement with bilateral firmness. Prostate-specific antigen level was 2.81ng/mL. Thus, magnetic resonance image examination was done, and it showed T2WI increasing signal intensity over prostate mass lesion with urinary bladder invasion and metastatic lymphadenopathy at bilateral internal iliac, external iliac, and the para-aortic spaces [Figure 2]. The bone scan indicated a low probability of metastasis. A thorough review of radiologic imaging studies did not reveal the presence of renal tumor. Therefore, the impression and clinical stage of this patient would be prostate CCA, T4N1M1a, stage IVB.
Figure 1: Computed tomography. A computed tomography image reveals prostate enlargement with calcification and heterogeneous enhancement rule out abscess and prostate cancer. (a) transverse view and (b) coronal view
Figure 2: Magnetic resonance image: mass lesion beneath the urinary bladder and suspicious invasion of the seminal vesical. (a) T2 weighted and (b) diffuse-weighted imagingNevertheless, a repeated transurethral biopsy was suggested. The cystoscopy was done, and it revealed a necrotic prostate mass with bladder invasion [Figure 3]. The resected specimen measured 1.6 cm × 0.4 cm × 0.3 cm in size and 20.4 g in weight. Grossly, it was grayish and elastic. A microscopic examination revealed tubulocystic or papillary structures lined by cuboidal or hobnail cells with clear to eosinophilic cytoplasm [Figure 4]. The immunohistochemical study suggested negative staining of prostate-specific antigen (PSA) (−), P501S (−), and GATA-3 (−) but positive staining of paired box 8 (PAX-8) (+), CD10 (+), and AMACR (+) [Figure 5].
Figure 3: Transurethral resection of prostate. Pale and necrotic tissue over prostate urethral (a), a hypervascular mass over right bladder neck (b)
Figure 4: The H and E staining. Tubulocystic or papillary structures lined by cuboidal or hobnail cells with clear to eosinophilic cytoplasm
Figure 5: The immunohistochemical staining. The immunohistochemical study revealed positive findings of PAX-8 (+), CD10 (+), and AMACR(+).The patient chose immunotherapy as the subsequent treatment because of the advanced stage of CCA based on pathologic similarities of metastatic CCRCC. Hence, he received two courses of anti-progressive disease (PD)-1 antibody, pembrolizumab. Nevertheless, the disease progressed rapidly as the lung and bone metastases were discovered after 4 months of treatment. He died 10 months after the diagnosis.
Discussion CCA usually presents in female genitourinary tracts such as diverticulum but rarely occurs in male.[1] Most of the previous cases of CCA were found in urinary bladder, testis, and urethra.[1],[2],[3] However, the prostate origin of CCA is an even rarer histologic diagnosis. To the best of our knowledge, there was only one case documented on PubMed.[4] We also reviewed other cases of CCA in men, listed in [Table 1].[4],[5],[6],[7],[8],[9],[10],[11],[12]
Table 1: Clinical summaries of reported clear cell adenocarcinoma in menIt could be easily misdiagnosed with CCRCC[13],[14] and RTCCC.[15] Since these tumors have similar histopathological characteristics, it is difficult to differentiate based on clinical and laboratory tests.
To confirm the diagnosis of CCA, tissue proof is extremely important. Most of the previous cases showed negative staining of PSA except one positive for PSA[10] and two showed positive for PAX-8.[4],[12]
PAX-8, a transcription factor, is a marker that indicates the differentiation of the tumor from kidney, thyroid, and Mullerian origin. According to a previous literature review, PAX-8 seems to be negative in RTCCC and in CCRCC.[15] Thus, it is a crucial marker to distinguish CCA from these two types of tumors.
As for PSA, most of the cases have negative staining of PSA except one case[10] and all the cases have normal serum PSA levels. This indicates that CCA is different from typical prostate adenocarcinoma.
In our case, immunostaining for GATA-3 was negative, which indicated that it did not originate from urothelial or neuroendocrine cells. In addition, the immunohistochemical staining did show positive staining of AMACR (P504S), confirming the prostate origin.
To date, there has been no standard treatment of CCA because of its scarce clinical evidence. However, if it is confined to local or regional area, radical cystoprostatectomy with ileal conduit is an option. However for metastatic diseases, there is no definite treatment. One of the cases received radical cystoprostatectomy with pelvic lymph node dissection but the tumor recurred afterward, so the patient received chemotherapy[8] and the other case received brachytherapy.[11]
Our patient had a prostate tumor with bladder invasion and lymph node metastasis in iliac and para-aortic regions at initial diagnosis. After two courses of pembrolizumab treatment, the follow-up computed tomography suggested PD with lung and bone metastases.
The prognosis is dismal in advanced or metastatic stages at initial diagnosis according to [Table 1]. Further follow-up information is required to evaluate the prognosis of CCA in men.
In all, CCA in male prostate is an extremely rare cancer that could present with a normal level of PSA levels. CCRCC and RTCCC should be included in differential diagnosis; however, primary CCA of prostate should be kept in mind when no evidence of kidney lesions was found in the image study.
Informed consent
Informed consent was obtained from the patient for the publication.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Acknowledgments
The authors would like to acknowledge the Department of Pathology and the Statistical Analysis Laboratory in the Department of Medical Research at Kaohsiung Medical University Hospital.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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