Various tumor and tumor-like lesions can occur in near the testes. A few have a positive epithelial component with adenomatoid tumor being the most common (14). Unlike vasitis nodosa, the epithelium of adenomatoid tumor is flattened, and the stroma is fibrotic (14). Our case did not show these morphologic features, and the lesional cells were centered on the lumen of vas deferens.
Vasitis nodosa and its counterpart in epididymis epididymitis nodosa were named for their resemblance to salpingitis isthmica nodosa (7, 15). Vasitis nodosa is the most common asymptomatic postoperative complication of a vasectomy and is identified in 50%-66% of the patients with the obstruction of the proximal end and associated inflammation. (1, 16). Most cases of vasistis nodosa occurred within 2 months to 19 years post operation (17). It was thought to be a result of a breach in the lining epithelium due to increased intravasal pressure and subsequent epithelial regeneration (18). This is could be attributed to an attempt at re-establishing the communication in an obstructed lumen and restoring the reproductive capacity of the individual (19). Recanalization has been reported in the presence of vasitis nodosa (20). Similarly, spermatic granuloma represents the body’s attempt to restore fertility by allowing sperm to leak into tissue (21). This hypothesis was indirectly supported by the observation that a better surgical sealing of the cut ends lead to a decreased incidence of vasitis nodosa and spermatic granulomas (21). Vasitis nodosa has also been identified in patients status post herniorrhaphy, chronic inflammation, bladder diverticulum, torture, and trauma (1, 3, 22). Vasitis nodosa can rarely arise in patients with none of these risk factors, and these lesions usually lack inflammation (3, 17). Presence of spermatic granulomas was thought to be associated at a better chance of impregnation (23). However, the result was not successfully reproduced in a later study (1). The persistent infertility after vasectomy reversal might be attributed to the development of antisperm antibody which has been detected in 50–70% patients after vasectomy (1).
The correct diagnosis of vasitis nodosa relies on the recognition of a benign process with seemingly malignant morphologic features. The florid proliferative activity of the epithelium can be misleading and easily misinterpreted as a malignant process. Atypical cytologic features such as vesicular nuclei, prominent nucleoli and mitotic figures can occasionally be present (16). The lesion can extend to involve the muscle layer and adventitia (1, 24, 25). Benign perineural and intraneural invasions have also been reported (4, 9, 16, 26). In one study, “benign neural invasion” was identified in 16% of the vasitis nodosa cases in which one or two nerves were invaded by one to eight glands (10). This was further complicated by nerve hyperplasia and neuromas (1). The phenomenon might be due to nerve growth factor expression which has been demonstrated in the epithelium of vasitis nodosa immunohistochemically (27). The epithelium in vasitis nodosa can also invade small veins or arteries which are almost always accompanied by elastosis (28). It has been postulated that proliferating ductules in vasitis nodosa invade the blood vessels after they have become obliterated by regressive and reparative processes (28).
Tumors can also mimic or colonize vasitis nodosa. Tumors especially of adjacent organs, such as prostatic adenocarcinoma and urothelial carcinoma with glandular differentiation can mimic the epithelial proliferation of vasitis nodosa (11). Presence of seminoma cells in the stroma or pagetoid spread inside tubules with concurrent testicular seminoma has been reported (12). Because no lymphatic, perineural, epididymis, or proximal vas deferens involvement could be demonstrated, it was hypothesized that the tumor cells may spread by shedding and subsequent arresting (12). A similar case of involvement of vasitis nodosa by germ cell tumors demonstrated unclassified germ cell neoplasia with pagetoid spread involving vasitis nodosa. The concurrent germ cell tumor was in the ipsilateral testis and contained no seminoma component (13).
Similar to the lining epithelium of vas deferens, the epithelial cells of vasitis nodosa are positive for cytokeratin 7 and 19, PAX8, CD10 and vimentin with patchy expression of GATA3 (8, 11). High-molecular-weight keratin 34betaE12 is present in the basal lining cells of the as deferens and vasitis nodosa (8). P63 is positive in basal cells of vas deferens lining epithelium but shows patchy expression in vasitis nodosa (11). In contrast to the lining cells, some vasitis nodosa cells are also positive for CA125 and AMACR (8, 11). However, other prostate markers such as PSA, prostein and NKX3.1 are consistently negative (11).
In conclusion, we report for the first time a case of vasitis nodosa with both phenotypes of vas deferens lining epithelium and mesothelium. Electron microscopy may be useful in eliminating the possibility that the nature of the proliferating cells is truly mesothelial (17).