Teaching Case

A 38-year-old patient presented with a painless paraurethral lump that had grown over the course of 2 years and become unesthetic unappealing. Pelvic examination revealed a soft, mobile right paraurethral mass measuring approximately 2 cm, with no signs of inflammation. Magnetic resonance imaging (MRI) was ordered for further evaluation.

The patient underwent pelvic MRI using T1-Weighted (T1W) and T2-Weighted (T2W) sequences, diffusion-weighted imaging (DWI) and contrast-enhanced imaging, with the use of vaginal gel.

MRI identified a round, well-defined nodule measuring 20 x 16 mm, located just right to the external urethral meatus, and slightly bulging the right labia (figure 1b). The lesion was inferior to the pubic symphysis (figure 1a) and had no connection to the urethral lumen. It presented homogeneous low signal intensity on T2W and T1W images (figures 1b and 1a), slight high signal intensity on b1000 DWI (figure 3a) and low signal on apparent diffusion coefficient (ADC) map imaging (figure 3b). Contrast-enhanced imaging showed slight heterogeneous enhancement (figure 2). No uterine leiomyomas were present. A right Skene's gland leiomyoma was suspected.

Surgical excision was performed, and histopathologic examination confirmed a diagnosis of leiomyoma, without necrosis, cellular atypia, or remarkable mitotic activity.

Background

Skene's glands are the female equivalent of the male prostate [1] and are situated on either side of the distal female urethra, occasionally extending into the urethrovaginal septum [2]. Their function is to lubricate the urethral opening and, in some women, produce ejaculate [1].

Skene's gland leiomyomas are benign tumours of mesenchymal origin [3] and a rare cause of paraurethral pathology [1, 4]. Although the aetiology of these tumours is unknown, they tend to occur in patients of reproductive age, influenced by female hormones [5]. Skene's gland leiomyomas may be asymptomatic, as in the case of our patient, or present with dyspareunia, dysuria, or voiding dysfunction [1].

Clinical and Imaging Perspective

Female paraurethral masses have a wide differential diagnosis and Skene's gland pathology must be distinguished from other lesions arising from the urethra, vaginal wall, Bartholin gland, and Gartner duct [1]. Following a thorough history and physical examination, imaging studies are useful in the diagnostic workup [6]. While perineal ultrasound may be helpful [5], pelvic MRI is the preferred imaging modality for assessing paraurethral masses [7]. MRI provides multiplanar imaging with superior soft-tissue contrast, furnishing critical information on lesion location, size, characteristics, and relationship to adjacent structures [6-9], which may suggest a specific diagnosis and guide patient management, particularly surgical planning [5].

In the presented case, MRI was ordered with those purposes and revealed characteristic imaging findings consistent with a Skene’s gland leiomyoma - a well-defined nodule just lateral to the external urethral meatus with homogeneous low signal intensity on T2W and T1W images and contrast enhancement [9].

Distinguishing Skene's gland leiomyoma from other paraurethral disorders can pose a challenge. However, a thorough evaluation of the lesion's location relative to the urethra and the MRI features can aid in differentiation. Urethral diverticula account for the majority of periurethral lesions [4]. These are fluid-filled cystic cavities that appear hyperintense on T2W images and arise from the posterolateral wall of the mid-urethra at the level of the pubic symphysis, sometimes demonstrating communication with the urethra [7, 10]. Skene’s gland cysts appear as round or oval T2 hyperintense lesions situated just lateral to the external urethral meatus [7, 10]. A solid lesion adjacent to the external urethral meatus may also represent urethral caruncle, Skene's glands adenofibroma, or Skene's glands adenocarcinoma. Urethral caruncles are most commonly observed in postmenopausal women and manifest as small T2 hyperintense lesions at the posterior margin of the external urethral meatus [10]. Skene's glands adenofibroma and Skene's glands adenocarcinoma are exceedingly rare conditions requiring histopathological diagnosis [1]. However, the presence of infiltrative growth or irregular margins raises suspicion of a malignant lesion [1, 9].

Outcome

Surgical excision is the preferred treatment option when a paraurethral mass is symptomatic [4]. Our patient was asymptomatic but presented with genital aesthetic concerns and surgical excision was decided.

Even though the risk of malignancy in a paraurethral lesion is low, a definitive histopathological diagnosis should be pursued when the lesion is suspicious [5]. In our case, a Skene’s gland leiomyoma was suspected on imaging, and the histopathological analysis confirmed the diagnosis.

Recurrence of Skene’s gland leiomyomas is exceedingly rare, and malignant transformation has not been reported [11].

Teaching Points

• Skene's glands are situated on either side of the distal female urethra.
• Skene's gland leiomyoma is a rare cause of paraurethral pathology.
• MRI is the best imaging modality for assessing paraurethral masses, with significant impact on patient management.

Written informed patient consent for publication has been obtained.