First Case of Abdominal and Tunica Vaginalis Multicystic Benign Mesothelioma: Management and Review of Literature

Abstract

Multicystic benign mesothelioma is a rare tumor that affects the serosa. Most cases present with peritoneal lesions exclusively. Some identified risk factors are chronic abdominal inflammation, woman of childbearing age, and asbestos exposure. The symptomatology is not specific and can delay the diagnosis. There are no guidelines for the treatment of this pathology. We describe one male patient with abdominal and tunica vaginalis localizations of multicystic benign mesothelioma. The diagnosis was suspected on imaging and confirmed with histological examination. The treatment on an expert center was complete cytoreduction surgery and HIPEC, but the patient had two recurrences during the 2-year of follow-up. This is the first case of simultaneous rare localizations of multicystic benign mesothelioma. No new risk factors were identified. The case underlines the importance of regular examination of all serosa localizations.

Introduction

The peritoneal cavity is the second location of mesothelioma after the pleura, but it can also affect rarer localizations such as the pericardium or the tunica vaginalis testis [1]. Peritoneal mesothelioma (PM) is a rare malignant primary peritoneal tumor, characterized by diffuse invasion of the peritoneal surfaces by tumor cells [2]. The average age of onset is 50 years with male preponderance (male female ratio 3:1) [3]. The prognosis is poor without appropriate treatment, with a 1-year survival [4]. Potential risk factors of mesothelioma are asbestos and micas exposure, abdominal radiotherapy, or genetic risk factors, but the pathophysiology is still poorly understood. The main symptoms are abdominal pain, nausea, transit disorders, and the presence of an abdominal mass. The curative treatment includes cytoreductive surgery associated in selected patients with hyperthermic intraperitoneal chemotherapy (HIPEC).

Benign multicystic peritoneal mesothelioma (BMPM) is a separate type of mesothelioma, characterized by the formation of multilocular intra-abdominal cystic masses. The incidence of BMPM is 0.15/100,000 annually, which makes it challenging to diagnose and treat. Less than 150 cases have been reported to date [5]. The association with asbestos is not proven. The revealing symptoms are the same as PM. BMPM frequently occurs in women of childbearing age, with a history of abdominal or pelvic surgery, pelvic inflammation or endometriosis, or familial Mediterranean fever (FMF) [6]. Thin-walled cysts are visualized on various imaging, but the diagnosis of BMPM is histological [7]. There is no consensus on management, but some teams recommend cytoreduction surgery with HIPEC for selected patient with BMPM. Although the prognosis is good, the evolution is marked by a high risk of recurrence (over 50%), but rare case of malignancy transformation was reported [8, 9].

Patient Information

We reported a case of BMPM with double rare localization: abdominal and vaginalis testis, from 35-year-old white male. He has a history of appendicular peritonitis at the age of 18, treated by stapling of the lower caecal fundus by sub-umbilical laparotomy, active smoking estimated to 15 pack-years, and lithotripsy for renal lithiasis. Patient is married, has one child, and he is carpenter.

Clinical Findings

Initial symptoms were abdominal pain and loss of 10 kg in 1 year. Exploration started with a complete blood panel which was strictly normal.

Diagnostic Assessment

The ultrasound and abdominal computerized tomography (CT) scan found a polycystic pelvic mass, between the rectum and the bladder (Fig. 1). Abdominal magnetic resonance imaging (MRI) confirmed multiple similar tumors in the para-colic gutters, the left hypochondrium, and the subhepatic region, suggesting initially peritoneal pseudomyxoma. The pelvic mass as well as inguinal nodes are seen in positron emission tomography (PET) CT scan (Fig. 1).

Fig. 1.

Abdominal CT scan and PET scan of benign multicystic peritoneal mesothelioma with abdominal and testis localizations

The first exploratory laparoscopy revealed cystic lesions, without mucin with a peritoneal carcinosis index (PCI) of 10. Biopsies confirmed the diagnosis of BMPM. All samples were sent to second histologist in order to confirm the diagnosis and the patient was transferred for the management.

During the consultation by the expert peritoneal surgeon, the clinical examination revealed a mass on the left testicle’s upper pole, associated with inguinal nodes. Testicular ultrasound and testicular MRI confirmed the presence of multicystic tumor on the left testicular. Node was not considered suspicious for a metastatic involvement in MRI. The tumor markers (alpha-fetoprotein and beta human chorionic gonadotropin) are non-contributory. The left inguinal nodes were removed first in order to confirm the absence of metastasis for this patient.

Therapeutic Intervention

A complete cytoreductive surgery (CRS) with HIPEC using cisplatin-doxorubicin was validated in a multidisciplinary oncological meeting after sperm cryopreservation. The exploratory laparotomy was performed and peritoneal carcinosis index (PCI) was 17 (Fig. 2). An omentectomy, cholecystectomy, partial douglasectomy, and resection of the round ligament of the liver, falciform ligament, and of all nodules on the mesentery and mesocolon were performed. The urologist performed the left orchiectomy. The cytoreduction was followed by cisplatin and doxorubicin HIPEC duration of 90 min at 42–43 °C. Patient had no postoperative complication, and histologist confirmed the diagnosis of BMPM (Fig. 3). Postoperative follow-up with clinical and imaging exams (CT scan or peritoneal MRI and testicular MRI) every 3–6 months during 5 years was discussed and validated in oncological meeting.

Fig. 2.

Preoperative picture of benign multicystic peritoneal mesothelioma

Fig. 3.

Picture of testis (a) and histology (b) with benign multicystic peritoneal mesothelioma

Follow-Up and Outcomes

Sixteen months after CRS and HIPEC, patient presented an abdominal recurrence. The abdominal MRI showed a cystic right pararectal lesion below the pouch of Douglass (Fig. 3). Because the PCI was low, multidisciplinary oncological meeting proposed to perform second CRS but without HIPEC and by coeliocopy. During the surgery, the surgeon confirmed that the lesion was below the pouch of Douglass, requiring the opening of this one to find the tumor. Patient had not postoperative complications and went home at 7-day postoperative. The histologist confirmed the recurrence of BMPM, and new follow-up was performed with radiological and clinical exams.

Then, 6 months after this second complete surgery, abdominal MRI suggested a second progression with news cystic left pararectal lesions (Fig. 4). The patient was asymptomatic and abdominal second MRI at 9 months after this second complete surgery was finally normal. A new follow-up was validated in multidisciplinary oncological meeting in September 2022.

Fig. 4.

RMI with the second recurrence of benign multicystic peritoneal mesothelioma

Discussion

BMPM is a rare tumor, the pathogenesis of which is poorly understood. Less than 150 cases have been reported in the literature. It is a primary disease of the serosa, characterized by multiple small cysts, with flattened lining containing calretinin-positive cells without atypical features, mitotic figures, or tissue invasion [10]. Unlike peritoneal mesothelioma, it is an indolent disease, although with a high recurrence rate, with only 1 case of malignant transformation reported in the literature.

We reported a first case of BMPM in a male patient with very rare localization: tunica vaginalis, abdominal peritoneum. The patient has not any risk factor such as history of abdominal surgery or radiotherapy. Although the pathogenesis is controversial, the risk factors of BMPM are history of inflammatory processes of the abdominal cavity, a history of endometriosis, chronic pelvic inflammation, and exclusively in women [6] (sex ratio is 3 women for one man, particularly women of childbearing age).

The diagnosis is made in a context of increased volume of the abdominal cavity as in this report case. There are no specific signs. The diagnosis is histological, and the case confirmed the necessity to transfer the patient to an expert team, to avoid error of diagnosis (pseudomyxoma in this case). In France, the diagnosis must be confirmed by second expert histologist and is declared to the health authorities.

Our clinical case is therefore extremely rare, firstly because BMPM mainly affects women of childbearing age, and secondly because of the clinical manifestations and diagnosis. Since the diagnosis of BMPM could be made rapidly, the involvement of the testicular vagina seems to be synchronous. The persistence of a peritonea-vaginal duct and consequence of the abdominal peritoneal involvement is the most logical hypothesis since the tunica vaginalis is derived from the abdominal peritoneum trough the inguinal canal [11], but, in our case, we did not find a left inguinal hernia.

Although not consensual because of the rarity of this entity [12–14], the surgical management is clear and consisted to resect of all visible cysts and the affected testis. The association with HIPEC is more discussed but can explain a disease-free period of 16 months in our case. Nevertheless, this patient presented recurrences, not only in abdominal peritoneum but also in subperitoneal level (under the Douglass’ pouch) (Table 1). This reveals a particular physiopathology of this disease with a high risk of recurrence which needs a specific follow-up.

Table 1.

Comparison between our case report and 2 previous case reports of BMPM of the tunica vaginalis

	Case A (our case)	Case B (Zazzara et al., 2019)	Case C (Lang et al., 2019)
Sex	Male	Male	Male
Age	35	83	74
Symptoms	Abdominal mass and weigh loss	Testicular swelling > 12 months	Testicular enlargement > 20 years
Risk factors	Abdominal surgery	None	Abdominal surgery
Diagnosis	CT scan	Ultrasound and CT scan	Ultrasound
Location	Abdominal peritoneum, subperitoneal pelvis, and tunica vaginalis	Tunica vaginalis	Tunica vaginalis
Treatment	HIPEC and CRS	Orchidectomy	Orchidectomy
Follow-up	22 months to date	6 months	N/R
Survival	22 months to date	N/R	N/R
Progression	2 recurrences	N/R	N/R

Conclusion

The diagnosis and management of benign multicystic mesothelioma are poorly codified, and this management is further complicated by unusual locations in this very rare entity. An increase in testicular volume with a cystic appearance on imaging should raise the diagnosis and search for other locations. Management should be done in an expert center.

Patient Perspective

The patient accepted the medical decisions after being informed of the benefits and risks of the treatment. He had no serious complications and returned to work quickly. He is currently being followed by our center.

Author Contribution

Ana Lucia Charlaix Hidalgo and Alexia Roux: Data Base, Methodology, Writing-Original Draft, and Review. Abdelkader Taibi: Conceptualization, Patient management, Data Base, Methodology, Writing-Original Draft, and Review. Aurelie Charissoux: Histology and Review. Others authors: Patient Management and Review.

Data Availability

All data generated or analysed during this study are included in this published article.

Declarations

Informed Consent

Informed consent patient was obtained and patient anonymity was respected.

Competing Interests

The authors declare no competing interests.