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Introduction

Adenomatoid tumours are usually presented as paratesticular masses. Paratesticular benign neoplasm’s are generally not encapsulated and are commonly presented between the structures of adjacent tissues and may show clear-cut infiltration [1]. Although most intratesticular tumours are malignant, paratesticular tumours are generally benign (accounting 70% of all). We report a rare case of adenomatoid tumour of the testis treated by local excision on the basis of Magnetic Resonant Imaging (MRI) scans suggesting benign impression.

Case report

A 28 year-old man was referred to our urology clinic with two-month history of a slowly enlarging and painless scrotal mass. He had no history of epididymitis, torsion, trauma, genitourinary surgery and constitutional symptom. Physical examination revealed 1 cm, nontender intrascrotal mass at the lower pole of the left testis. Serum levels of the alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (ß-hCG) and lactate dehydrogenase (LDH) were within normal limits. Scrotal ultrasonography (US) revealed a 15x13 mm heterogeneous regular contour mass in the lower pole of the testis and the mass relatively hypoechoic to the epididymal parenchyma. The mass did not bulge the outer counter of the testis. With the ultrasonogaphic findings, the mass was thought to arise from the tunica albuginea or epididymis and preoperative scrotal MRI was performed to verify this impression. Scrotal MRI was performed using fast spin echo T2-weighted images in the coronal-oblique and sagittal planes. Before and after contrast administration T1-weighted images were performed in the coronal-oblique and sagittal planes. MRI revealed a 1.5 cm mass which had regular contour and heterogeneous parenchyma. The mass had hyperintense and hypointense parenchyma according to epididymis and testis in T1 and T2-weighted images, respectively (Figure 1). After IV gadolinium administration, minimum contrast-enhancement was observed by solid mass (Figure 2). The patient underwent left inguinal exploration with local excision of only the intratesticular lesion. Histological examination revealed benign fibrous, smooth muscle and mesothelial proliferation, consistent with an adenomatoid tumour growing down into the testicular tissue from the inner surface of the tunica albuginea (Figure 3). At 9 months of follow-up, no disease recurrence was observed.

Discussion

Adenomatoid tumours are the most common paratesticular neoplasm’s and account for approximately 30% of all paratesticular neoplasm’s and are rare benign neoplasm’s of the mesothelial origin and commonly found near the lower pole of the testis [2, 3]. These tumours usually arise in the epididymis; however, they have been reported in the spermatic cord, suprarenal recess, prostate, ejaculatory duct and tunica albuginea in men and in the uterus and fallopian tubes of women [4,5]. The clinical presentation is almost invariably a mass swelling, which may or may not be painful and is occasionally accompanied by a hydrocele. These findings are by no means specific to a tumour type and cannot distinguish a benign from a malignant tumour [6].

High-resolution scrotal ultrasonography remains the primary imaging method and when used with the appropriate clinical data, may be extremely helpful in establishing the diagnosis. In general, benign tumours are homogeneous and hyperechoic, whereas malignant ones are either homogeneously hypoechoic or have a heterogeneous pattern of hypo- and hyper- echoic areas. However, the ultrasonographic appearance may be misleading and homogeneous; hyperechoic liposarcoma has been reported [7]. MRI may locate the tumour better and define its relationship to various paratesticular structures in greater detail, which, is not always possible with ultrasonography [8]. A recent study which involved 12 cases of paratesticular adenomatoid tumour has provided immunohistochemical evidence indicating a mesothelial cell origin [9]. The only local mass excision with inguinal incision was performed on the basis of the slow growth history, the small tumour size, normal serum levels of tumour markers (AFP, ß-hCG, LDH) and imaging methods (MRI, US). The superior portion of the testis and the epididymis were normal. MRI findings were useful in suggesting that the palpable mass arose from tunical surface or in the testis. MRI showed that a 1.5 cm mass had regular contour and heterogeneous parenchyma. The mass had hyperintense parenchyma in T1-weighted images and hypointense parenchyma in T2-weighted images according to epididymis and testis. Watanabe et al. have found that dynamic contrast-enhanced MRI evaluation may be useful in distinguishing testicular tumour from other testicular disorders; in this series malignant testicular tumour had increased contrast enhancement compared with contralateral normal testicular parenchyma [10]. The adenomatoid tumour showed less contrast enhancement than ipsilateral testicular parenchyma and contralateral parenchyma. This finding confirms to the prediction of benignity of the mass based on the work of Watanabe et al [10]. The potential value of MRI is further evaluation of scrotal disease when sonographic features are insufficient or unusual. MRI evaluation may provide additional morphologic evidence precise localization and the origin of the mass.

Conclusion

We report this case because of the rarity of intratesticular adenomatoid tumour and the importance of organ-sparing surgery by preoperative MRI images. MRI evaluation may be a useful diagnostic tool, if there is any doubt in considering rare benign intratesticular neoplasm’s in the differential diagnosis of testicular masses with normal levels of preoperative serum tumour markers. However, the MRI is not widely available and is an expensive technique, which limits its routine use in the clinical practice. It’s also experienced staff dependent. Until disappearance of these difficulties, this technique with MRI should be considered as a part of clinical studies, before it is accepted as a cost-effective technique in the clinical practice.

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Sahin Kabay
Dumlupinar University Faculty of Medicine
Department of Urology
43100 Kuthaya, Turkey
Phone +90274 2652031
skabay@yahoo.com