Prostatic leiomyoma

Prostatic leiomyomas are benign mesenchymal tumors of the prostate.

Epidemiology

Prostatic leiomyomas are very rare ^1-3.

Diagnosis

The diagnosis of prostatic leiomyoma is based on histology.

Clinical presentation

Prostatic leiomyomas can present with voiding difficulties or obstructive symptoms ¹.

Complications

Complications of prostatic leiomyomas include acute urinary retention ¹.

Pathology

Leiomyomas of the prostate are characterized as benign smooth muscle tumors without any glandular elements located within the prostate or in a juxta-prostatic position ^1-4.

Macroscopic appearance

Grossly tumors have been described as well-circumscribed with a glistening or smooth surface and a multilocular cystic cut surface ⁵.

Microscopic appearance

Microscopically leiomyomas of the prostate are characterized by the following histologic features ^5,6:

• bland spindle cells with a prominent eosinophilic cytoplasm
• organized fascicular architecture
• no or rare nuclear atypia
• no or scarce mitoses
• no necrosis

Immunophenotype

Immunohistochemistry stain should express desmin or smooth muscle actin but should be negative for CD34 ^1-3.

Radiographic features

Ultrasound

On transrectal ultrasound, leiomyomas have been described as nonspecific hypoechoic or hyperechoic masses ^2-4.

CT

Computed tomography might show a heterogeneously enhancing but otherwise noninvasive appearing soft tissue mass ^2,4.

MRI

On prostate or pelvic MRI  have been characterized as well-delineated and without signs of invasive behavior ^2-4.

Signal characteristics

• T1: overall isointense
• T2: hypointense to slightly hyperintense with hyperintense foci (compared to muscle)
• DWI: diffusion restriction (hyperintense on high-b value, hypointense on ADC)
• DCE (Gd): homogeneous slow enhancement

Radiology report

The radiological report should include a description of the following:

• form, extent and location of the tumor
• description of its borders
• relation to seminal vesicles, bladder and rectum

Treatment and prognosis

Management options consist of surgical excision either as transurethral resection or prostatectomy. Prognosis is excellent if excised completely ^1-3. More recent options include prostate artery embolization or active surveillance in asymptomatic patients ^2,3.

History and etymology

The first case of prostatic leiomyoma was reported by Lebec et al in 1876 ¹. The definition has been formulated by Kaufmann and Berneike in 1951 ^1,7.

Differential diagnosis

Conditions that may be mimicking the clinical presentation or imaging appearance of  prostatic leiomyomas  include ¹:

• benign prostatic hyperplasia
• leiomyosarcoma of the prostate
• stromal tumor of uncertain malignant potential
• solitary fibrous tumor