Testicular Tuberculosis: A Comprehensive Clinical Review

Introduction

Testicular tuberculosis (TB) is a rare but significant manifestation of genitourinary tuberculosis, often posing diagnostic challenges due to its clinical resemblance to testicular malignancy. In regions with a high prevalence of tuberculosis or in immunocompromised patients, it must be considered as a differential diagnosis for testicular masses.

Case Summary

A 42-year-old man presented with a two-month history of painless enlargement of the left testis. He denied fever, night sweats, weight loss, respiratory symptoms, or urethral discharge. On examination, the left testis was enlarged, firm, and non-tender. Pelvic MRI revealed a lobulated left testicular mass with heterogeneous enhancement (Figure 1). Serum tumor markers for testicular cancer were negative.

Radical inguinal orchiectomy was performed due to suspicion of malignancy. Gross examination showed necrotic nodules (Figure 2). Histopathology revealed granulomatous inflammation with caseous necrosis (Figure 3) and acid-fast bacilli (Figure 4). PCR confirmed Mycobacterium tuberculosis. Chest CT was normal. The patient received a 9-month anti-tubercular regimen and remained healthy at 1-year follow-up.

Figures

Figure 1. T2-weighted MRI showing a lobulated left testicular mass with heterogeneous enhancement.

Figure 2. Gross specimen of excised testis showing necrotic nodules.

Figure 3. Histopathology demonstrating caseous necrosis.

Figure 4. Histopathology showing acid-fast bacilli (arrows).

Cause and Etiology

Testicular TB is caused by Mycobacterium tuberculosis, typically spreading to the testes via:

Hematogenous dissemination from a primary pulmonary or extrapulmonary focus.
Retrograde spread from the prostate, seminal vesicles, or epididymis.
Rarely, lymphatic spread.

In most cases, epididymo-orchitis due to TB begins in the epididymis before involving the testis. Isolated testicular TB without epididymal involvement is extremely rare.

Pathophysiology

The pathogenesis involves:

Initial infection—bacilli reach the epididymis/testis through hematogenous or retrograde routes.
Granulomatous inflammation—the immune system walls off the bacilli, forming granulomas.
Caseous necrosis—immune-mediated destruction results in central necrosis, characteristic of TB.
Fibrosis and calcification—chronic infection may lead to fibrosis, scarring, and calcification, potentially impairing fertility.

Epidemiology

Genitourinary TB accounts for 20–40% of extrapulmonary TB cases.
Testicular involvement is rare—less than 5% of genitourinary TB cases.
A higher incidence is observed in TB-endemic countries.
More common in immunocompromised individuals, particularly HIV-positive patients.

Clinical Presentation

Typical features include:

Painless testicular swelling (most common).
Firmness on palpation.
Absence of systemic TB symptoms in many cases.
It may be mistaken for testicular cancer, especially when unilateral.
Occasionally presents with a scrotal sinus or fistula in advanced disease.

Imaging Features

MRI and Ultrasound are essential for differentiation:

Ultrasound: Heterogeneous hypoechoic mass, possible calcifications.
MRI: Lobulated, heterogeneously enhancing mass (Figure 1), hypointense on T2-weighted images due to fibrosis and necrosis.
CT scan: Useful for detecting other TB foci.

Diagnosis

Histopathology—granulomas with caseous necrosis (Figure 3).
Acid-fast bacilli staining—Ziehl–Neelsen stain positive (Figure 4).
PCR for M. tuberculosis—highly sensitive.
Exclusion of malignancy is critical before final diagnosis.

Treatment

The cornerstone of therapy is anti-tubercular treatment (ATT):

Standard regimen: 2 months of intensive phase (Isoniazid, Rifampin, Pyrazinamide, Ethambutol) + 4–7 months of continuation phase (Isoniazid, Rifampin).
Surgery (orchiectomy) is indicated when:
- Malignancy cannot be excluded.
- Extensive destruction or abscess formation.
- Failure to respond to ATT.

In the presented case, radical orchiectomy was performed before diagnosis due to suspicion of cancer.

Prognosis

With prompt ATT, the prognosis is excellent.
Untreated cases risk infertility, chronic pain, and dissemination.
Recurrence is rare with complete treatment.
Fertility preservation is possible if the diagnosis is made early.

Quiz

1. What is the most common route of spread for testicular tuberculosis?

(A) Lymphatic spread
(B) Hematogenous spread
(C) Direct extension from rectum
(D) Retrograde spread from the epididymis

2. Which imaging finding is characteristic of testicular TB on MRI?

(A) Uniform hypointensity on T1
(B) Lobulated mass with heterogeneous enhancement
(C) Pure cystic lesion
(D) Homogeneous hyperintensity on T2

3. What is the histopathologic hallmark of tuberculosis?

(A) Microabscesses
(B) Caseous necrosis with granulomas
(C) Fibrous scar tissue
(D) Reactive hyperplasia

Answer & Explanation

1. Answer: D. Explanation: Most cases originate from epididymal TB via retrograde spread to the testis.

2. Answer: B. Explanation: MRI often reveals a lobulated, heterogeneously enhancing mass, reflecting granulomatous inflammation and necrosis.

3. Answer: B

Explanation: TB is characterized by granulomatous inflammation with central caseous necrosis.

References

[1] S. Kulchavenya, “Extrapulmonary tuberculosis: are statistical reports accurate?,” Ther. Adv. Infect. Dis., vol. 2, no. 2, pp. 61–70, 2014.
[2] N. Muttarak et al., “Tuberculous epididymitis and epididymo-orchitis: sonographic appearances,” AJR Am J Roentgenol, vol. 176, pp. 1459–1466, 2001.
[3] F. Figueiredo et al., “Epididymal tuberculosis: a review,” Int J Urol, vol. 15, pp. 830–835, 2008.
[4] World Health Organization, “Global tuberculosis report 2023,” Geneva: WHO, 2023.
[5] J. C. Lee et al., “Isolated tuberculous orchitis: imaging findings,” J Ultrasound Med, vol. 33, no. 6, pp. 1095–1100, 2014.
[6] S. M. Cho et al., “MRI features of tuberculous epididymo-orchitis,” Clin Radiol, vol. 66, pp. 1093–1099, 2011.
[7] N Engl J Med, “Case study 52: Testicular tuberculosis,” N Engl J Med, vol. 389, e13, 2023.

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