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Serous borderline tumor of the paratestis in a child

We report a rare case of serous borderline tumor of the paratestis in a child.



Departments of Urology1 and Pathology2 Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan

Corresponding Author: Haruo Kato,  Departments of Urology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.   Email: [email protected]


Reported herein is a rare case of serous borderline tumor (SBT) of the paratestis in an 11-year-old boy. The patient presented with left scrotal hydrocele and paratesticular induration. Tumor markers were negative, and an inflammatory disease was suspected from magnetic resonance imaging. Three months later, left scrotal pain developed, and a left scrotal exploration was undertaken to examine the acute scrotum. Intraoperative findings showed the possibility of a malignant tumor and a left inguinal orchiectomy was performed. Microscopic examination revealed papillary epithelial proliferations lined by multiple layers of columnar epithelium with mild nuclear pleomorphism. On immunohistochemical analysis, the tumor cells were negative for calretinin. SBT of the paratestis identical to ovarian epithelial tumor is very rare, especially in a child. Although no SBT of the paratestis has recurred or metastasized, the long-term prognosis has not been extensively studied. In pediatric cases such as the present case, long-term follow-up is considered necessary.


While serous tumors of borderline malignancy (serous borderline tumor, SBT) are common in the ovary, the corresponding tumors in the paratestis including tunica vaginalis and tunica albuginea are very rare. SBT of the paratestis was first reported by Young and Scully in 19861, and subsequently approximately only 15 cases of SBT of the paratestis have been reported. Most have been found in adults, and few cases in children. We here report the youngest case of SBT of the paratestis in an 11-year-old boy.


Case report
An 11-year-old boy was seen at our hospital because of painless induration in the left hemi-scrotum. He had a diagnosis of left hydrocele 2 years earlier. Physical examination revealed a left scrotal in which a hard mass other than the testis was palpable. The right testis was normal. Scrotal ultrasound revealed hyperechoic lesions at upper and lower poles of the left testis. Serum human chorionic gonadotropin (hCG) and alpha fetoprotein levels were normal. Magnetic resonance imaging (MRI) revealed 2 enhancing nodular lesions 15 mm and 9 mm in diameter at the upper and lower poles of the left testis, respectively (Fig.1).


Fig 1. Magnetic resonance imaging (MRI)


We suspected inflammatory disease originating from a tumor identified by MRI and followed up the patient at the outpatient clinic.
Three months later, the patient presented with acute left scrotal pain after an exercise activity that lasted for 5 hours. Left scrotal tenderness and swelling were noted. Hematological and urine test results were normal. Scrotal ultrasound findings were the same as before. A left scrotal exploration was performed for the acute scrotum. The intraoperative findings showed various lesions that originated from the tunica vaginalis of the left testis, including nodular, papillary, and calcified lesions. The scrotum contained bloody fluid. We could not discount the possibility of a malignant tumor and performed a left inguinal orchiectomy (Fig.2).


Fig 2. Specimen 


The cytology of the bloody fluid contained in the scrotum was class Ⅲ. Microscopic examination revealed papillary epithelial proliferations lined by multiple layers of columnar epithelium without stromal invasion. The tumor cells had mild nuclear pleomorphism and lightly eosinophilic cytoplasm. Focal deposits of calcium were seen between the tumor cells (Fig.3).


Fig 3. Focal deposits of calcium were seen between the tumor cells


On immunohistochemical analysis, the tumor cells were negative for calretinin (Fig.4).


Fig 4. Immunohistochemical analysis



The definitive histological examination showed a “serous papillary tumor of borderline malignancy.”
 The scrotal pain was identified as being caused by bleeding from the tumors. The pain disappeared after surgery, and the patient was discharged on the 4th postoperative day. Computed tomography (CT) was negative for lymph nodes and metastasis, and follow-up was conducted at the outpatient clinic without additional treatment.


Epithelial tumors identical to ovarian mullerian tumors are rare in the paratestis. The characteristics of these tumors are not well defined. Most mullerian-type tumors of the paratestis are SBTs. Although an origin from remnants of mullerian ducts in the male appendix or mullerian metaplasia of the lining surface of the mesothelium of tunica vaginalis has been suggested, the pathogenesis of this tumor is controversial.1,2,3
In the ovary, SBTs are composed of cell types resembling those of the fallopian tubes, and have low malignant potential. Atypical epithelial proliferation of serous cells is greater than that of their benign counterparts but without destructive stromal invasion. 4 SBT of the paratestis has pathological features identical to ovarian mullerian tumors.
McClure et al. reported the largest series of 7 cases of SBT of the paratestis. The patients ranged from 14 to 77 years of age (mean 56 years, median 65 years) and the tumors ranged from 1 to 6 cm in size, arising from the tunica albuginea or the tunica vaginalis. 5 There have been few childhood cases reported with respect to the paratestis, and this is the youngest case of SBT of the paratestis to date.
All patients were treated with orchiectomy except for one patient who underwent wedge resection. Follow-up data showed no recurrence or metastasis of the tumors for a period from 4 months to 18 years, suggesting a good prognosis.5 However, in ovarian SBTs, late-onset recurrence, metastasis, or occasionally transformation to invasive carcinoma can occur.6 Therefore a prolonged follow-up is recommended. This is particularly necessary for SBT of the paratestis, especially in a childhood cases similar to the present case.
Most patients with SBT of the paratestis have a painless mass in the paratestis. The most evident initial symptom is hydrocele with or without an associated mass. In the present case, although the patient had a painless mass in the left hemiscrotum, inflammatory disease was suspected rather than the tumor indicated by MRI. It might be necessary to explain the possibility of the tumor sufficiently and take early operation into consideration in case a paratesticular nodule with hydrocele is detected.
It is important to distinguish SBT of the paratestis from malignant mesothelioma. Histologically, a typical SBT is a noninvasive proliferative neoplasm characterized by multiple fibrous papillae with extensive and complex hierarchical branching. Detachment and exfoliation of cells from the papillae are characteristic features. Some of the exfoliated cells are eosinophilic and have a rounded shape. The epithelial cells generally show only mild to moderate nuclear atypia.7 On the other hand, well-differentiated mesothelioma contains fibrous papillae lined by a single layer of cuboidal mesothelial cells. Immunohistochemical analysis is helpful for differentiating between SBT and mesothelioma. A large number of immunohistochemical markers have become available for diagnosis of malignant mesothelioma. Among these markers, the calcium binding protein calretinin is one of the most used in the diagnosis of malignant mesothelioma because of its high sensitivity and specificity, and is frequently expressed in all histologic types of malignant mesothelioma, in contrast with other highly sensitive mesothelioma markers. The best combination appears to be calretinin and cytokeratin 5/6 (or WT1) for the positive markers and CEA and MOC-31 (or B72.3, Ber-EP4, or BG-8) for the negative markers because of their specificity and sensitivity for mesothelioma.8
 In conclusion, this is a report of a rare case of SBT of the paratestis in an 11-year-old boy, representing the youngest case to date. SBT of the paratestis is rare and not well studied. Although no SBT of the paratestis has recurred or metastasized after resection to date, the length of the follow up period is controversial, especially in a childhood case. More experience with this type of tumor is necessary, and we hope to continue  longterm follow up of the present case.


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2 Remmele W, Kaiserling E, Zerban U et al. Serous papillary cystic tumor of borderline malignancy with focal carcinoma arising in testis: case report with immunohistochemical and ultrastructural observations. Hum. Pathol. 1992; 23:  75–9.
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7 Hart WR. Borderline epithelial tumors of the ovary. Mod Pathol. 2005; 18: S33–50
8 Ordonez NG. The immunohistochemical diagnosis of mesothelioma: a comparative study of epithelioid mesothelioma and lung adenocarcinoma. Am J Surg Pathol. 2003; 27: 1031–51


Date added to 12/01/2012 

DOI: 10.1002/BJUIw-2011-089-web

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