Teaching Case

A 60-year-old male presented with one month of progressively worsening back pain, difficulty ambulating, and decreased sensation in the bilateral lower limbs. He was found to have a painless right testicular mass. Initial bloodwork (CBC, electrolytes, LFTs, and creatinine) was benign, and the patient was admitted for further assessment.

Initial greyscale US imaging showed multiple small hypoechoic lesions throughout the testis and a right hydrocele (Figure 1a). Colour Doppler US revealed a heterogeneous, hypoechoic, mildly vascular mass infiltrating the right testis and epididymis (Figure 1b). Urology and interventional radiology deferred testicular biopsy to avoid malignant seeding risk.

The CTAP (computed tomography arterial portography) revealed bony destruction centred at T10–T11 with a rim-enhancing paravertebral collection (Figure 2). To further characterise these findings, an MRI spine was performed. The MRI revealed marrow oedema on T2-weighted images (Figure 3a), and enhancement of the vertebrae and paraspinal phlegmon on post-contrast T1-weighted images (Figure 3b).

The CT chest showed spiculated masses in the right lung with architectural distortion and numerous smaller lung nodules with a miliary distribution on axial views (Figure 4a). Additionally, coronal views showed bony destruction centred at the left sternoclavicular and first sternocostal joints with involvement of the surrounding soft tissue (Figure 4b).

Background

Tuberculosis (TB) remains a significant health challenge worldwide despite advances in diagnosis. Before the COVID-19 pandemic, TB was the most prevalent infectious disease in the world. Genitourinary tuberculosis (GUTB) is the most common site of extrapulmonary involvement in patients with tuberculosis (TB), making up 20% of cases in endemic areas [3,4]. However, of these, only 3% involve the scrotum [4]. Its pathophysiology can involve heterogeneous spread directly to the epididymis from sexual contact, albeit exceedingly rare [5]. Generally, it is through retrograde spread through the urinary tract. The epididymis is typically the first genital organ affected due to its high vascularity [6,7].

Clinical Perspective

Typically, scrotal GUTB presents as a painless or slightly painful mass with variable US findings, which makes it difficult to differentiate from typical epididymal-orchitis or other conditions such as tumours or infarction [8]. It is often missed clinically due to a lack of suspicion among clinicians, unreliable clinical manifestations, and insidious indolent onset. As such, it still requires the presence of Mycobacterium tuberculosis in a clinical sample, which can often result in diagnostic delay and subsequent disease progression, increased risk of infertility, and in some cases, irreversible organ damage [1].

Imaging Perspective

Scrotal GUTB generally appears as a diffuse heterogeneous epididymis that is predominantly hypoechoic or has an intrinsic focal nodular hypoechoic lesion. On colour Doppler, it demonstrates increased flow, allowing for differentiation from infarction. Testicular GUTB presents as a miliary pattern of lesions, with general diffuse enlargement. This differs from testicular tumours, which often present as a single, well-defined hypoechoic mass [9]. If testicular GUTB is suspected, CT can assess systemic involvement, including miliary patterns in the lungs and other organs [10].

Outcome

Antituberculous treatment has an excellent prognosis for GUTB with historical cohorts indicating cure rates of close to 100% can be expected [11]. However, due to a paucity of diagnostic imaging with high sensitivity and specificity, radical surgery is currently unavoidable for some patients [12]. Our patient was diagnosed with GUTB based on both imaging features and sputum samples which were positive for TB PCR and acid-fast bacilli. The patient had TB skin testing before starting his biologic, which was negative. Ultimately, he was able to avoid orchiectomy and was started on antituberculous treatment with RIPE therapy. Follow-up scrotal US was arranged.

Take Home Message

Diagnostic consideration of genitourinary tuberculosis (GUTB) amongst radiologists with US and CT may facilitate prompt diagnosis and timely initiation of anti-tuberculosis treatment, ultimately preventing surgical management and improving outcomes.

Written informed patient consent was obtained for the publication of this research.