A systematic review was conducted utilizing the Preferred Reporting Items for Systematic Reviews (PRISMA) (3). We searched in PubMed, Web of Science databases, Embase, and Medline in the English language from 1970 to December 2021. The keywords used were “Leiomyoma” and “prostate”. All the case reports and series studies were included in this research. All non-English, review articles, for which we could not obtain a full text, were excluded. We extracted the following details of each article: first author, date of publication, country, numbers of patients, age, symptoms, PSA, DRE, the size of the tumor, position, biopsy or not, imaging examinations, initial diagnosis, treatment, follow-up and malignancy.

After the selection procedure according to PRISMA (Figure 4), a total of 21 studies were included in our systematic review (1, 2, 4, 6–23). There were 35 cases of leiomyoma of the prostate included for analysis and characteristics of the cases are shown in Table 1.

The average age of the patients was 63.86 ± 1.94 years old. The average size (diameter) of the tumors was 5.73 ± 1.03 cm. Leiomyoma of the prostate appeared more frequently in 50–60 year old men (26%) and 60–70 year old men (41%). It rarely occurred in young men <40 years (3%) (Figure 5A). With regard to diagnosis, a biopsy was performed in about 51% cases to obtain a preoperative diagnosis or to distinguish the mass from a malignant prostate tumor (Figure 5B). About 17% cases of leiomyoma of the prostate combined with other malignant tumors, such as prostate cancer or bladder cancer (Figure 5C). For treatment, the majority of cases were subjected to surgical treatment (74%), and only 11% cases were selected for active surveillance (Figure 5D). In the past approximately 50 years, the surgical method of choice for leiomyoma of the prostate has gradually changed from open surgery to minimally invasive surgery (Figure 6). Meanwhile, imaging examinations for leiomyoma of the prostate have changed from X-rays or intravenous pyelograms to computed tomography (CT), MRI, and positron emission tomography-CT (PET-CT) (Figure 6).

Leiomyoma of the prostate occurs more frequently in middle-aged or older men (17). Previous reports have shown that the average age of patients is 63.86 ± 1.94 years old (ranging from 35 to 82 years old). Leiomyoma of the prostate occurs more frequently in 50–60 year old men (26%) and 60–70 year old men (41%). It occurs rarely in young men. In our review, only one case was thirty-five years old (4). In our case report, the patient is a thirty-year-old man. To our knowledge, our case presents the youngest male who has suffered from a leiomyoma of the prostate.

Leiomyoma of the prostate has non-specific symptoms. On digital rectal examination, we found a solid prostate mass. Previous reports have shown that lower urinary tract symptoms are common. These include dysuria, urinary frequency, significant nocturia, urgency, painful micturition and acute urinary retention (1, 4, 19). Gross haematuria is a rare symptom, and in our systematic review, only 3 cases reported gross haematuria (10, 17, 18). A large leiomyoma in the prostate posterior lobe would place pressure on the rectum leading to constipation (13).

Leiomyoma of the prostate is sometimes difficult to distinguish from benign prostatic hyperplasia or prostate cancer. In older men, leiomyomas are usually combined with benign prostatic hyperplasia and other malignant tumors, such as prostate cancer or bladder cancer (15, 16). Some leiomyomas of the prostate have been identified in surgical specimens of benign prostatic hyperplasia, prostate cancer and bladder cancer (12, 15).

Few reports have described the features of imaging examinations (14, 15). A hypoechoic or hyperechoic lesion in the prostate may be evident in transrectal ultrasonography (1, 12). A mass of the prostate in the pelvis can be seen in CT imaging (14). These masses are usually well-circumscribed nodules or masses and no lymphadenopathy or distant metastasis may be detected. PET-CT would exhibit no hypermetabolic mass of the prostate (1).

MRI features of leiomyoma of the prostate reveal a well-circumscribed round mass, with isointense and homogeneous signals relative to the muscle on T1WI. A slightly hyperintense or hypointense well-circumscribed mass with a capsule around the tumor between the normal prostate, seminal vesicles, rectum and other organizational structures are exhibited in a T2WI image (23). The capsule is clearly visible in MRI axial fat-suppressed T2-weighted images. It is a feature of a benign tumor. Other traditional and new imaging methods may provide us with more other useful information to make a correct diagnosis, such as TURS, CT, PET-CT.

In our case, the clear surgical capsule around the tumor could be seen in MRI imaging and helped us to make a differential diagnosis from prostate cancer. This capsule was not the tumor's intrinsic capsule. During surgery, along with the capsular space and the external intrinsic capsule of the tumor, we resected the prostate mass completely and were able to spare the prostate. Thus, we referred to it as the surgical capsule.

In general, the PSA of a prostate leiomyoma or leiomyo sarcoma is at a normal level. Abdollahi's study found that PSA has little clinical utility in the diagnosis of leiomyoma (24). When prostate leiomyoma is combined with BPH or prostate cancer, the PSA level becomes raised (12, 20). Biopsy is then useful in assisting with a correct diagnosis. In previous reports, biopsies were performed on about 51% cases before surgery. A preoperative biopsy of the prostate in a small prostate leiomyoma or a prostate leiomyoma of irregular shape is necessary as it is difficult to distinguish between prostate malignant tumors, such as leiomyoma sarcomas, adenocarcinomas and retrovesical ectopic prostatic adenomas (25). We recommend that a prostate biopsy should be performed before the preparative radical prostatectomy to confirm the diagnosis and avoid excessive diagnosis and therapy. And prostate biopsy is necessary for patients who choose nonsurgical treatment to avoid the risk of cancer.

In our case, the PSA was at a normal level, the age of the man was young and on MRI the characteristics of a benign tumor were exhibited. This information did not appear to support a diagnosis of cancer. Nevertheless, we recommend that patients undergo prostate biopsies preoperatively. Moreover, the behavior of the patient was an important factor in our choice of treatment. After communicating with him, he refused to undergo a biopsy as he feared that he would have to wait too long for surgery after the biopsy.

When there is a medical history of no, or few, lower urinary tract symptoms, evident characteristics of a benign tumor in imaging examinations, and negative tumor markers, leiomyoma of the prostate should be included in the differential diagnosis.

The final diagnosis may be reached by histopathological and immunohistochemical analysis (12, 20). The mass of leiomyoma of the prostate is usually well circumscribed, with a smooth surface. It is a homogeneous solid mass with gross features similar to that of a uterine leiomyomas. The mass is composed of bland spindle proliferating cells on microscopic evaluation. No atypical mitosis, pleomorphism or glandular component is identified. In immunohistochemical analysis, the spindle cells are positive for smooth muscle actin (SMA) and desmin. CD34 is negative, in contrast to stromal tumors of unknown malignant potential.

Methods of treatment for leiomyoma of the prostate have changed in the past decades. Prostatectomy was considered the standard surgical approach for leiomyomas of the prostate before the 1990s (10). For aging men, leiomyoma of the prostate frequently combines with benign prostatic hyperplasia. With the development of endoscopic surgery, the transurethral resection of the prostate (TURP) has been gradually applied to the treatment of leiomyoma of the prostate. However, it is important in the case of young men to protect their sexual functioning. At present, with the development of laparoscopy technology, prostate-sparing and simple tumor surgical removal is achievable for pelvic or retroperitoneum tumors (26). However, use of this surgical technique has been rarely reported in studies of leiomyoma of the prostate. In our case, with the assistance of laparoscopy, we resected the prostate mass completely, and the prostate was spared. Furthermore, the urinary and sexual functioning of the patient was preserved after surgery. The key to success in prostate sparing is accurately identifying the surgical capsular space.

Prostate artery embolization is a treatment option for men who are not suited to surgical treatment (1, 23). Active surveillance of asymptomatic patients with a low risk of prostate cancer is necessary. The key to successful nonsurgical treatment lies with the selection of appropriate candidates.

Leiomyoma of the prostate is a benign tumor. No reports have indicated recurrence of prostatic leiomyomas after surgical removal. In our case, one year after follow-up, there was no evidence of recurrence.