Xanthogranulomatous prostatitis masquerading as prostate cancer: a case report and literature review

Abstract

Objectives

Xanthogranulomatous prostatitis (XGP) and prostate cancer (PCa) are difficult to distinguish based on clinical presentation and imaging, and diagnosis relies on pathological biopsy.

Patients and Methods

A case report of XGP, accompanied by a literature review.

Results

We report one case of XGP and summarize the clinical features of 28 previously reported cases.

Conclusion

The fPSA/tPSA ratio, PSA detection and PET-CT may be useful tools for differentiating XGP from PCa. Diabetes may contribute to the development of XGP.

Background

Xanthogranulomatous prostatitis (XGP) is a rare and under-recognized benign inflammatory condition that can clinically and radiologically mimic prostate cancer. Due to its overlapping features with malignancy, misdiagnosis is common, often leading to unnecessary invasive procedures [1]. This case is noteworthy as it highlights the diagnostic challenges posed by XGP, especially in the context of elevated PSA, abnormal MRI findings (PI-RADS 5), and clinical infection. Reporting this case contributes to raising awareness of XGP and emphasizes the importance of histopathological confirmation in such diagnostic dilemmas.

Case report

Upon admission, the 78-year-old patient presented with elevated serum markers: total PSA (tPSA) was 8.429 ng/mL and free PSA (fPSA) was 5.250 ng/mL. Given the increased inflammatory markers (CRP 116.4 mg/L, WBC 18.3 × 10^9/L) and lower urinary tract symptoms, a urinary tract infection was suspected, and empirical antibiotic therapy was initiated. The patient had no history of recent antibiotic use prior to admission. On day 5 of hospitalization, the patient developed a low-grade fever (maximum 38.1 °C), which resolved by day 9. Inflammatory markers showed improvement by day 10.

During hospitalization, urologists were consulted. Although they initially recommended PSA monitoring and follow-up, the patient strongly requested further investigation to exclude malignancy. Prostate multiparametric MRI was performed and interpreted using the PI-RADS v2.1 system, revealing a PI-RADS 5 lesion with hyperintensity on DWI (b-value = 1800) in the peripheral zone, highly suggestive of prostate cancer (Fig. 1).

Fig. 1.

Prostate MRI Imaging. Tip: The radiologist pointed out that the prostate enlarged, the DWI signal in the peripheral area increased, and the ADC signal weakened. The maximum length and diameter of the abnormal signal area was 17.4mm, and the PI-RADS5 score was highly indicative of cancer

Interestingly, one day prior to biopsy, repeated testing showed normalized PSA and fPSA levels. Despite this, considering the highly suspicious MRI findings and the patient’s clinical presentation, a transrectal ultrasound-guided prostate biopsy was performed on day 11. Eight targeted cores were obtained, yielding 12 pathology specimens. The extended hospitalization duration was due to infection control, symptom monitoring, and coordination of the biopsy procedure. At a follow-up two months later, he reported no urinary symptoms, the PSA level had decreased to 0.847 ng/mL, and inflammatory markers were within normal limits.

Discussion

XGP, first described by Tanner and McDonald in 1943, is a rare and poorly understood subtype of prostatitis [2]. To date, most of the literature on XGP consists of isolated case reports. In this study, we present a case of XGP that closely mimicked prostate cancer both clinically and radiologically, and we review relevant cases from the literature to enhance understanding of this diagnostic challenge. Although the patient’s total PSA and free PSA levels had returned to normal just one day before the planned biopsy, the decision to proceed was driven by several key considerations. Most notably, the multiparametric MRI revealed a PI-RADS 5 lesion, which, according to the 2024 Prostate Cancer Guidelines [3], necessitates histopathologic confirmation regardless of PSA values. In addition, the patient had persistent lower urinary tract symptoms and a recent episode of low-grade fever, raising the possibility of inflammatory prostatitis. Nevertheless, given the substantial overlap in clinical presentation and imaging findings between XGP and prostate cancer, non-invasive evaluations alone were insufficient to exclude malignancy. A definitive diagnosis through biopsy was therefore considered necessary and ultimately led to the identification of XGP.

On August 1, 2024, a search was conducted on PubMed for published English-language articles using the keyword “xanthogranulomatous prostatitis.” This study only included articles with full-text access. A manual search of the reference lists of the identified articles was also performed to find additional studies. The PubMed search yielded 41 articles, with 17 excluded for being irrelevant or having incorrect content, and 6 excluded for not reporting PSA values. A total of 18 articles were included, comprising 28 cases. In the study published by Antonio Luigi Pastore et al. in 2013, only the upper and lower limits of age and PSA were reported. This study used their data to randomly generate five corresponding values.

The information from the relevant literature is listed in Table 1, and Fig. 2 illustrates the distribution of the related clinical features. The majority of patients were over 50 years old. 75% of the patients underwent surgical treatment, with the main procedure being subtotal prostatectomy. The remaining 25% received non-surgical treatment, including but not limited to antibiotics, antiandrogen therapy, or treatments not specified in the literature. Among them, 7 patients had concurrent prostate cancer. Additionally, the two outlier high PSA values (PSA = 200 ng/mL and PSA = 150 ng/mL) were from these patients. In Fig. 3, after excluding patients with cancer, the highest PSA value was 49.19 ng/mL, with the majority of patients having PSA values around 10 ng/mL. Approximately 18% of the patients were explicitly reported to have a history of diabetes, while the remaining patients either had no past medical history mentioned in the reports or were not associated with diabetes.The patients reported in the study presented with the following symptoms: urinary retention, a history of hematospermia, urinary irritation (such as hesitancy, weak urine flow, frequent urination, urgency, and difficulty urinating). The majority of patients exhibited urinary irritation and urinary retention. This is consistent with the urinary irritation symptoms observed in the patients reported in this study. Fortunately, these patients generally had a good prognosis after treatment, especially in the absence of concurrent PCa.

Table 1.

A Review of the relevant literature on XGP

Publication Date	Author	Number of Cases	Age (years)	PSA (ng/mL)
2022	Yongxiang Tang [5]	1	56	49.19
2022	Al-0imi A [8]	1	63	6
2021	Chenelle M.C. Joseph [4]	1	65	2.4
2021	Jo0than Demeter [9]	1	65	1.23#
2020	Sampi Mehta [10]	1	60	0.8
2020	Yang Che-Hsueh [11]	1	70	200#
2020	Mukendi Alain Mwamba [12]	1	71	9.5#
2019	Kumar 0veen [1]	1	57	11.59
2017	Prakriti Shukla [6]	1	65	8.85#
2017	Alejandro Noyola [13]	1	47	0.9
2016	Kumbar Rajeshwaroi [14]	5	67	6
			63	5.5
			81	4.8
			65	5.2
			75	6.2
2015	Daniel A. WOLLIN [15]	1	78	41.5
2014	Yue Cheng [16]	2	71	5.5
			60	6.5
2013	Antonio Luigi Pastore [17]*	5	62	6
			59	4.8
			51	6.3
			54	6.7
			60	5.4
2012	Hsiang-Ying Lee [18]	1	74	11.74
2010	Paari Murugan [19]	1	59	20#
2006	Muhammad Rafique [20]	1	60	150#
2005	Harsh Mohan [21]	2	67	2.8
			70	10#

Tip: The * marked references only provided the age and PSA value ranges, this study generated corresponding values using random number generation. The # marked in the PSA values indicates that the study reported the patient had concurrent PCa

Fig. 2.

Clinical Features in the Literature Review of XGP. Tip: Fig A describes the distribution of age; Fig B describes the distribution of patients who underwent surgical intervention; Fig C describes the distribution of concurrent PCa; Fig D describes the distribution of concurrent diabetes; Fig E describes the distribution of PSA levels in all patients; Fig F describes the distribution of PSA levels after excluding PCa patients. In five cases, the data on age and PSA were randomly generated based on the upper and lower limits in the corresponding literature

Fig. 3.

Prostate Biopsy Pathology. Tip: The pathologist indicated that the tissue shows extensive infiltration of inflammatory cells, along with numerous foamy histiocytes. Immunohistochemical PSA (-),CD68 (+), and CD163 (+)

The etiology of XGP is not fully understood, but it may be related to recurrent urinary tract infections or immune responses [4]. Due to its clinical presentation and imaging features being highly similar to prostate cancer, XGP is often misdiagnosed [5]. The pathological features include significant infiltration of foamy cells, macrophages, and lymphocytes into the prostate tissue, often accompanied by necrosis and fibrosis [6]. In this case, the patient was CD163 + and CD68+, which is consistent with macrophage infiltration, and PSA (-), P63 (+), and HCK (+), which ruled out prostate malignancy. The definitive diagnosis of XGP requires a pathological biopsy. However, as a non-malignant disease, the benefits of invasive diagnostic procedures compared to the harm they cause to the patient warrant further discussion. PSA is often significantly elevated in prostate cancer, but it can also be elevated in XGP. In previous cases, PSA levels were around 10 ng/mL, with the highest level in XGP-only patients reaching 49.19 ng/mL⁵. XGP typically occurs in patients over 50 years old and may be accompanied by mild PSA elevation, often placing XGP in the PSA “gray zone” of 4–10 ng/mL. The 2022 prostate cancer guidelines indicate that an fPSA/tPSA ratio (free PSA to total PSA) of less than 0.1 is diagnostic when PSA is between 4 and 10 ng/mL, with a prostate cancer prevalence of 56% at that level [7]. In this study, the fPSA/tPSA ratio was 0.622, which aligns with this observation.Previous reports lack fPSA testing, and the fPSA/tPSA ratio may be a potential key to differentiating between XGP and prostate cancer. mpMRI and 68Ga-PSMA PET/CT are mentioned in the guidelines as major diagnostic tools for prostate cancer [7]. Tang et al. reported one case where 68Ga-PSMA PET/CT was helpful in diagnosing XGP, which was difficult to distinguish from prostate cancer using mpMRI alone [5]. However, the financial burden of PET/CT for patients is also a matter of consideration.In past literature reviews, the prognosis of XGP with non-surgical treatment has been acceptable. Using empirical medication to control urinary symptoms, followed by PSA monitoring and imaging during follow-up, seems to be a viable differential approach before proceeding with invasive procedures. Miekoś, E.‘s study published in 1986 identified two XGP patients, both of whom had diabetes [2]. In this study’s case review, 18% of patients were explicitly reported to have a history of diabetes, suggesting that a hyperglycemic environment may be one of the causes of XGP. This study has several limitations. First, as a single case report, the findings may not be generalizable. Second, the retrospective literature review is subject to selection and publication bias. Third, heterogeneity in data reporting across reviewed cases limited comparative analysis. Fourth, long-term follow-up data for our patient is lacking. Finally, our observations require validation in larger prospective cohorts.

Conclusion

The fPSA/tPSA ratio, PSA detection and PET-CT may be useful tools for differentiating XGP from PCa. Diabetes may contribute to the development of XGP.

Authors' contributions

J and S wrote the main manuscript text and S provided writing ideas. All authors reviewed the manuscript.

Funding

This research was supported by the Public Welfare Application Project of Huzhou Science and Technology Bureau, with the project number 2022GYB11.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Written informed consent was obtained from the patient for the publication of this report and any accompanying images (202502004-02, Ethics Committee of Huzhou Central Hospital) .

Consent for publication

Stating that the participant consented for their data to be published.

Competing interests

The authors declare no competing interests.