Vasitis Nodosa: A Rare Diagnosis for Inguinal Swelling

Vasitis nodosa involves benign, reactive spindle-shaped nodular thickening of the ductal epithelium of vas deferens. We report the case of a 21-year-old male with a history of bilateral undescended testes and left orchidopexy. The patient presented with the complaint of a non-tender left inguinal swelling. The definitive diagnosis of vasitis nodosa was made based on clinical evaluation and imaging findings. We suggest that this rare entity should be considered as a differential diagnosis of inguinal swelling during the assessment of the male urogenital system.


Introduction
Vasitis nodosa refers to a benign condition, in which the ductular epithelium of the obstructed vas deferens undergoes reactive proliferation, forming fusiform nodular thickening. It may occur following an infection or either surgical or non-surgical trauma. Only 90 well-documented cases have been reported so far since the first description of the disease in 1943 [1,2]. Clinical evaluation of symptoms with detailed history, imaging findings, and follow-up are the key factors in the identification of vasitis nodosa and involves excluding differential diagnoses to prevent unnecessary surgery.

Case Presentation
Our patient was a 21-year-old male with no known comorbidities, who presented with the complaint of swelling in the left inguinal region for three months. He had a history of bilateral undescended testes for which he had undergone left orchidopexy at the age of eight years. Agenesis of the right testis was noted at the time of surgery. He had no history of fever, trauma, tuberculosis, alcohol consumption, cigarette smoking, or high-risk sexual behavior. On examination, there was swelling in the left inguinal region, which was non-tender on palpation. There was no associated erythema or pigmentation.
His initial MRI with contrast showed diffuse thickening of left vas deferens showing intense post-contrast enhancement. An initial diagnosis of vasitis was made, and antibiotic treatment was given. No response to treatment was noted [ Figures 1, 2

Discussion
Vasitis is a rare entity characterized by Chen and Schlegel as acute painful infective vasitis and asymptomatic vasitis nodosa [1]. First described by Benjamin in 1943, vasitis nodosa is the benign chronic inflammation resulting in the fusiform nodular thickening of vas deferens [2]. The pathogenesis of the disease is believed to be secondary to an extensive proliferation of ductular epithelium with infiltration into the muscular layer and adventitia. This proliferation of epithelium results in luminal occlusion of vas deferens with increased intraluminal pressures causing leakage of spermatozoa and subsequent granuloma formation and fibrosis [3,4]. Most cases have a previous history of vasectomy or surgeries in close proximation of vas deferens, such as herniorrhaphy, perianal fistulectomy, or prostatectomy [5]. Vasitis nodosa has been reported in 66% of patients who had undergone vasectomy [1,6]. Our patient had undergone orchidopexy due to undescended testis, which was the most probable cause of vasitis nodosa in this case.
Clinical presentation is with asymptomatic inguinal swelling due to nodularity in vas deferens, which requires no treatment as seen in our patient. Various imaging modalities can be used for the evaluation of vasitis, which include ultrasonography, CT, and MRI. Ultrasonography is used to exclude common differentials, such as inguinal hernia, orchitis, epididymitis, and testicular torsion. On ultrasound, normal vas deferens is seen as non-compressible, anechoic, or hypoechoic tubular structure with total thickness ranging from 1.5 to 2.7 mm (mean, 1.89 mm) and a luminal diameter ranging from 0.2 to 0.7 mm (mean, 0.43 mm) [7]. Vasitis nodosa appears as hypoechoic thickened vas deferens, which may show minimal flow on ultrasonography. CT and MRI are more accurate in confirming the diagnosis and evaluation of the extent of vas deferens involvement, thus preventing extensive workup and unnecessary interventions required in other disorders affecting vas deferens and the male urogenital system.
Kovi and Abgata have reported the benign neural invasion in cases of vasitis nodosa, emphasizing the fact that it can mimic low-grade adenocarcinoma of vas deferens [8]. The exact mechanism of neural invasion is not known; however, it is postulated to be due to entrapment of the ductal epithelium by the damaged regenerating nerve fibers after surgery [9]. Another possibility is the benign invasion of peripheral nerves by the proliferating ductal epithelium in an attempt for recanalization after vasectomy. Vasitis nodosa can be differentiated from adenocarcinoma on histopathology by identification of a preserved pattern of branching ductal proliferation with intraductal spermatozoa, identified on eosin and hematoxylin staining. Therefore, the pathologist should also be well aware of this rare entity to avoid misdiagnosis of vas deferens adenocarcinoma.

Conclusions
Vasitis nodosa is a rare entity and should be considered as a differential diagnosis for inguinal swelling, especially in patients with a history of undescended testes, vas deferens, or perineal surgery. Clinical presentation with asymptomatic inguinal swelling resulting from vas deferens nodularity requires no treatment. CT and MRI scans can play a critical role in diagnosis to prevent unnecessary surgical procedures.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.