Introduction
Paratesticular fibrous pseudotumor, which is a rare benign lesion that is not a real tumor but a reactive fibrous inflammatory hyperplasia [
1], was first described by Sir Astley Cooper in 1830 [
2]. Besides the generally accepted term “fibrous pseudotumor,” this lesion has been assigned many other names, including chronic proliferative periorchitis, fibromatous periorchitis, reactive periorchitis, inflammatory pseudotumor, granulomatous periorchitis, and nonspecific paratesticular fibrosis [
2].
Fibrous pseudotumor is usually discovered by chance, and it has no special symptoms. Its pathogenesis remains ambiguous, and it is possibly related to injuries or inflammation. Fibrous pseudotumor is usually well-defined with a rigid texture, and mainly consists of hyalinized collagen. The primary purpose of diagnosis is to differentiate between benignity and malignancy. Ultrasound is the initial modality of imaging, but magnetic resonance imaging (MRI) or computed tomography (CT) and frozen section during operation have limited functions. The prognosis of fibrous pseudotumor is good because no apparent evidence on potential malignancy currently exists. We present five cases of fibrous pseudotumor in the paratesticular region, and the relevant literature was reviewed.
Case report
This report comprised five men with fibrous pseudotumors (Table 1), who were referred to our hospital between 2000 and 2013. The average age of these patients was 36 years old (ranging from 21 to 60 years old), and the average duration from the onset of symptoms to proper treatment was 3.6 years (ranging from 1 to 10 years). All cases presented with unilateral scrotal masses with no other special symptoms and previous history. Routine laboratory examinations were within normal limits. Scrotal Doppler ultrasound showed three cases of nodules and two cases of diffuse incrassation of tunica vaginalis with hydrocele (Fig. 1). Considering the possibility of benign lesions based on a long duration and a small lesion, patient 1 underwent local excision. The preoperative biopsy of patient 2 showed adenoma, and the intraoperative frozen section of patient 3 showed fibrous pseudotumors. Thus, local excision was performed for both patients. Patient 4 and patient 5 underwent right radical orchiectomy because ultrasound showed a cystic lesion with multiple calcification, thereby implying possible malignancy. Additionally, atrophy of the testis was observed in patient 4. Postoperative pathological examination showed that all were fibrous pseudotumors. Macroscopically, the three nodular cases (patients 1, 2, and 3) presented single, firm, round, and white nodules with diameters of approximately 1 cm. The remaining two diffuse cases presented incrassated tunica vaginalis with diameters greater than 4 cm, with completely encased atrophied testes compressed by a large amount of hydrocele (Fig. 2). Microscopically, a widely hyalinized collagenous lesion with variable degrees of lymphocyte infiltration was observed (Fig. 3A). Mitotic figures were absent or infrequent. Immunohistochemistry showed the following results: vimentin (+), pancytokeratin (focal+), epithelial membrane antigen (EMA) (focal+), calretinin (–), Wilms’ tumor 1 (–), cytokeratin 5/6 (–), CD34 (–), smooth muscle actin (SMA) (–), and desmin (–) (Fig. 3B, 3C, and 3D). Postoperative recovery was uneventful, and all patients recovered well without recurrence during an average follow-up of 26 months.
Discussion
Paratesticular fibrous pseudotumor originates from intrascrotal tissue, such as tunica vaginalis, epididymis, or spermatic cord [
1], and accounts for nearly 6% of all paratesticular lesions and tumors [
3]. Approximately two-thirds of reported cases arise from the tunica vaginalis, with 10% from the epididymis, and rarely is it associated with the tunica albuginea or spermatic cord [
4]. Besides the two cases of nodules that were located in the epididymis, three cases were located in the tunica vaginalis in our report. Fibrous pseudotumor has been reported in all age groups, and the peak incidence is in the third decade of life. However, it is rare in patients younger than 18 years old. As in our cases, all patients were older than 18 years old, and four cases were about 30 years old.
Most patients presented with a painless scrotal mass for several years, but other symptoms may arise from the hydrocele because half of the cases are associated with hydroceles [
5]. The pathogenesis is due to a reactive fibrous inflammatory hyperplasia, which is a likely response to trauma, surgery, infection, or inflammatory hydrocele [
1], but this response was not confirmed in our cases.
Macroscopically, fibrous pseudotumors are mainly manifested as firm and white nodules, which are well-defined, ovoid, and mobile structures. They may be single or multiple and occasionally associated with diffuse fibrosis of the testicular tunic. A previous study reported that the sizes of nodules range mostly from 0.5 cm to 8.0 cm [
3], which was consistent with our cases. Microscopically, fibrous pseudotumors are composed of dense fibrous tissue that consists of hyalinized collagen and spindle fibroblasts in variable proportions. Mitotic figures are absent or infrequent. Other findings may include calcification, ossification, myxoid change, granulation, and a mixed chronic inflammatory infiltration of lymphocytes, plasma cells, and histiocytes [
1].
The sonographic appearance of the fibrous pseudotumor typically appears as a solid lesion with variable echogenicity depending on its component, such as the amount of fibrous tissue, cellular component, and presence or absence of calcifications. Shadowing may occur due to the dense fibrous stromal tissue. The color flow of the scrotal Doppler ultrasonography can show a moderate amount of vascularity within the lesion. Tumor markers (e.g., AFP, HCG, or LDH), abdominal ultrasound for retroperitoneal lymph nodes, and chest X-ray could be performed to exclude testicular cancer if suspected. MRI is also helpful for diagnosis and follow-up. Fibrous pseudotumor shows intermediate to low signal intensity on T1-weighted images and uniformly very low signal intensity on T2-weighted images [
6].
The primary purpose of diagnosis is to differentiate between benignity and malignancy, which is helpful for guiding treatment. In the differential diagnosis of fibrous pseudotumor, paratesticular lesions (adenomatoid tumors, hydroceles, leiomyoma, and malignant tumors) and scrotal lesions (tunica albuginea cysts and malignant tumors) should be included and considered. Differential diagnosis should be possible in most cases by assessing the morphology of the lesion and associated radiologic features, and correlating them with clinical information [
7]. The initial imaging modality for distinguishing intratesticular from extratesticular lesions is ultrasound. Fibrous pseudotumors have no special tumor markers. Gordetsky considered that it may be difficult to make a diagnosis of fibrous pseudotumor by intraoperative frozen section on a limited specimen [
8]. Similarly, the preoperative biopsy of patient 2 showed adenoma, which was not consistent with the postoperative pathology in our report. A reported review showed positive immunoreactivity for vimentin, SMA, and muscle-specific actin, and negative reactivity for CK, desmin, S-100 protein, factor VIII-related antigen, CD31, CD34, inhibin, melan-A, and carcinoembryonic antigen [
9]. At all events, definitive diagnosis requires postoperative pathological examination.
Fibrous pseudotumors are rare, and surgical exploration is usually performed for the need to exclude a malignant process. Local excision could be performed instead of radial orchiectomy for a high possibility of a benign diagnosis. Radical orchiectomy is usually performed when the malignancy is uncertain or in cases in which the tunics are too diffusely involved to allow preservation of the testicular tissue [
10]. In our report, three cases underwent local excision because of benign evidence, such as long progression-free duration, benign biopsy, or frozen section, whereas the remaining two cases underwent radical orchiectomy because the malignancy was uncertain and testicular atrophy was observed.
Compliance with ethics guidelines
Zhicheng Zhang, Jun Yang, Mingchao Li, Wei Cai, Qingquan Liu, Tao Wang, Xiaolin Guo, Shaogang Wang, Jihong Liu, and Zhangqun Ye all declare that they have no conflict of interest. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and the Helsinki Declaration of 1975, as revised in 2000. Informed consent was obtained from all patients for inclusion in the study.
Higher Education Press and Springer-Verlag Berlin Heidelberg
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