Tuberculous epididymitis following intravesical Bacillus Calmette–Guérin immunotherapy

A 65-year-old patient presented at the emergency department with painful and progressive monolateral scrotal swelling. It presented left testicular enlargement, tenderness, and induration on physical exam. Blood tests revealed mild leukocytosis (11.86 x10E9/L). One year ago, the patient underwent transurethral resection of a 3 cm tumour on the left lateral bladder wall. The patient is currently undergoing maintenance with BCG, having received the last dose 3 months ago.

A scrotal ultrasound was performed. It showed bilaterally enlarged epididymis with presence of bilateral nodular lesions, one in the head of the right epididymis measuring approximately 16 mm in the major axis (Figures 1 and 2), and three adjacent nodules in the body of the left epididymis measuring approximately 16, 13, and 10 mm (Figures 3 and 4). These nodular lesions are hypoechoic and heterogeneous, with one of them showing central hypoechoic areas suggestive of necrotic changes. They do not show increased Doppler signal, which is predominantly peripheral (Figures 2 and 4). Both testicles had preserved morphology, echostructure and normal Doppler signal. There was a small hyperechoic image of 2 mm in the left testicle, suggestive of a small calcification, without evidence of other focal parenchymal lesions. There was evidence of bilateral hydrocele and bilateral varicocele, predominantly right.

Background

“BCGitis”, or BCG-induced tuberculous epididymitis, is a rare granulomatous infection caused by Bacillus Calmette–Guérin therapy. It has been described in a small number of cases to affect several anatomic locations, including the lungs, the bones, the epididymis and the testicles, among other locations [1].

The bacillus of Calmette–Guérin (BCG) is a weakened form of Mycobacterium bovis, that was introduced as a treatment for urothelial bladder cancer when instilled directly into the bladder. By doing so, these mycobacteria elicit an inflammatory and immune response that leads to the destruction of tumour cells. Currently, the combination of BCG therapy and transurethral resection of bladder tumour is considered the preferred treatment for bladder lesions staged T1 or lower [2].

Clinical Perspective

Clinically, patients may present a painless or slightly painful scrotal mass, and so is difficult to differentiate from typical epididymitis or other conditions such as tumours or infarction. Therefore, the role of imaging becomes highly relevant as it allows for initial diagnostic guidance (biopsy may be required for a definitive diagnosis) and assessment of the severity of the condition. In our case, a biopsy was performed, which showed chronic granulomatous epididymitis with central necrosis consistent with tuberculous origin. Also, the Ziehl–Neelsen staining was also positive, identifying acid-fast organisms.

Imaging Perspective

The first-choice imaging technique is ultrasonography. It generally shows diffusely heterogeneous, predominantly hypoechoic, enlarged epididymis or a focal nodular hypoechoic lesion within it. Preferentially, the tail is involved while the head is spared. The heterogeneity may be due to caseating necrosis, granulomas and/or fibrosis. Other associated sonographic findings include linear or focal Doppler signal at the periphery of the epididymis, as well as thickened scrotal skin, hydrocele, lack of clear separation between the epididymis and the testis, intra-scrotal extra-testicular calcification (in the epididymis and in the tunica vaginalis of the testis), scrotal abscess, and scrotal sinus tract [3].

A heterogeneous, enlarged epididymis favours tuberculous involvement over non-tuberculous involvement as it may show homogenous echotexture of enlarged epididymis. Increased colour flow differentiates this condition from infarction.

Outcome

Antituberculous chemotherapy is the mainstay of treatment. Epididymectomy may be required for diagnosis or treatment. This condition may result in infertility.

Take Home Messages

Identifying granulomatous or tuberculous epididymitis based on radiological findings can be challenging, as it closely resembles bacterial epididymitis, malignant testicular conditions, and testicular torsion. Historically, the diagnosis of tuberculous epididymitis has relied on histological examination after surgery. However, recognizing its sonographic appearance can aid in avoiding unnecessary surgical interventions.

All patient data have been completely anonymised throughout the entire manuscript and related files.