Mesothelioma of the tunica vaginalis: a series of eight cases with uncertain malignant potential

Intratesticular Mullerian Serous Borderline Tumor With Microinvasion: A Rare Tumor and Review of the Literature

Ovarian-type (ie, Mullerian) epithelial tumors occurring in the testicular and paratesticular regions are exceptionally rare, with only a handful reported worldwide. Serous tumors are the most frequently encountered subtype among these rare tumors. The pathogenesis of these tumors within the testicular and paratesticular regions remains a subject of intrigue and debate, with various hypotheses attempting to explain their presence in the paratestis region, where most tumors occur. However, our understanding of the pathogenesis of intratesticular tumors is limited. To date, 11 known examples of intratesticular serous Mullerian tumors have been reported globally. In this report, we present an extraordinary tumor, an intratesticular Mullerian serous borderline tumor with foci of microinvasion, in a 38-year-old male patient. This tumor exhibits histological features similar to their ovarian counterparts and is confirmed through an immunohistochemical panel. Our report underscores the extreme rarity of these tumors, emphasizes the importance of heightened awareness among clinicians and pathologists, and provides valuable insights into their complex development and histogenesis. This contribution aims to enhance diagnostic precision and optimize therapeutic strategies for similar tumors.

[Paratesticular mesothelioma: A rare case report]

Paratesticular mesothelioma is a very rare tumour, accounting for 0.3 to 1.4% of all mesotheliomas. Mesothelioma arising from the spermatic cord is extremely rare with only a few cases reported in the literature. We report a case of spermatic cord mesothelioma in a 70-year-old man who presented with a right inguinal mass and pain.

Case report: Abdominal mesothelioma in Atelerix albiventris

Hedgehogs, as exotic species, are more susceptible to various neoplastic conditions affecting diverse bodily systems, particularly the tegumentary, hemolymphatic, and digestive systems. Among these conditions, epithelial tumors are the most prevalent, followed by round cell tumors and mesenchymal tumors. A striking characteristic is the malignant nature of over 8% of these tumors, leading to a generally unfavorable prognosis. This study aims to present a unique case involving a 2.5 year-old male African pygmy hedgehog in Concepción, Biobío District, Chile, diagnosed with a mesenchymal neoplasia originating from mesothelial cells. The hedgehog presented to the veterinary clinic with acute abdominal pain, prompting ultrasound imaging, and comprehensive cytological, histopathological, and immunohistochemical analyses. During abdominal ultrasound, a mass was observed, and its cytological examination revealed the presence of malignant cells. The histopathological examination unveiled a diffuse mesothelial cell tissue interwoven with abundant fibrous tissue and small cysts containing serous fluid, all enveloped by flattened or cuboidal cells of mesothelial origin. Immunohistochemistry further confirmed the diagnosis, demonstrating positive immunostaining for calretinin and mesothelin markers, corroborating the diagnosis of fibrous malignant peritoneal mesothelioma. This case highlights the complexity of neoplastic conditions in hedgehogs and emphasizes the importance of multimodal diagnostic approaches for accurate identification and understanding of these rare diseases.

Identification and Management of Testicular Mesothelioma Identified Intraoperatively: A Case Series

Testicular mesothelioma lacks the characteristic presentation of testicular malignancy and often has normal biomarkers at the time of diagnosis causing this malignancy to be overlooked and diagnosed intraoperatively during elective scrotal surgery. We present two cases of testicular mesothelioma that were diagnosed incidentally during hydrocelectomy. These cases emphasize the importance of considering testicular mesothelioma during hydrocele and scrotal mass workup and demonstrate the need for standardized guidelines for the management of testicular mesothelioma.

Mesothelioma of Uncertain Malignant Potential (MUMP) of the Tunica Vaginalis: Proposal for Reclassification as "Complex Mesothelial Tumor of the Tunica Vaginalis"

A well-differentiated papillary mesothelial tumor (WDPMT) and malignant mesothelioma are 2 well-recognized entities arising from the testis tunica vaginalis. Another mesothelial lesion exclusively seen at this site is mesothelioma of uncertain malignant potential (MUMP)-a lesion reminiscent of WDPMT yet demonstrating variable proportions of more complex architectural patterns that could be confused with invasion. MUMP was first described in 2010 with a total of 11 cases reported to date. Herein, we describe 19 additional patients who underwent hydrocelectomy, excision, and/or orchiectomy. Novel morphologic patterns found in addition to the 2010 series include spindle cells, keloidal-type collagen, and multicystic architecture lined by bland mesothelial cells. Clinical follow-up in 9 patients for more than 1 year (1.5 to 22.5 y, median 4.5 y) revealed no evidence of disease recurrence or metastases. Despite greater architectural complexity, MUMP has (1) bland cytology; (2) merging in with WDPMT areas; (3) low mitotic rate and Ki-67 nuclear labeling index; (4) retention of MTAP and BAP1 expression; and (5) benign clinical follow-up. If these cases were malignant mesotheliomas, one would have expected at least some of the patients to demonstrate disease recurrence/progression without adjuvant therapy within the available follow-up time, particularly with limited resection in most patients. Thus, we propose that "mesothelioma of uncertain malignant potential" be renamed as "complex mesothelial tumor of the tunica vaginalis." Using the term "complex" draws a contrast with the simple cuboidal lining and simple papillary architecture seen in WDPMT. Also, labeling the lesion as "tumor" removes the stigmata of "uncertain malignant potential" and "mesothelioma" that are alarming to patients and clinicians, and potentially could unduly lead to more extensive surgery in an attempt at "complete" resection. At the same time, not definitively labeling the lesion as benign allows recommendations for follow-up.

Well-Differentiated Papillary Mesothelial Tumor of the Scrotum with Suspicious Invasion

Well-differentiated papillary mesothelial tumor (WDPMT) is a distinct form of mesothelioma with low malignant potential and is mostly found in the peritoneal cavity. It consists of mesothelial cells with papillary structure and bland cytology. We report a rare case of WDPMT with suspicious invasive foci in the tunica vaginalis. WDPMT with invasive foci is known to have a tendency for recurrence. Therefore, careful attention should be given to properly diagnosing and treating this rare entity.

Testicular/paratesticular mesothelial tumours: Uncommon histopathologic entities in a very complex anatomical site

Mesothelial tumours of the testicular/paratesticular region are uncommon, poorly characterised and difficult-to-diagnose lesions. They encompass entirely benign proliferations (adenomatoid tumour) and malignant, very aggressive tumours (mesothelioma) whose morphological features can be overlapping, highly variable and confounding. Moreover, testicular/paratesticular mesothelial tumours comprise relatively new entities with indolent behaviour (well-differentiated papillary mesothelial tumour) as well as tumours which cannot be correctly included in any of the aforementioned categories and whose classification is still controversial. The molecular profile of such tumours represents an open issue. In fact, despite the recent discoveries about the genomic landscape of mesothelial proliferations at other sites (pleura, peritoneum), testicular/paratesticular mesothelial tumours, and namely mesotheliomas, are too rare to be extensively studied on large case series and they could arguably hide relevant differences in their molecular background when compared to the more common pleural/peritoneal counterparts.The aim of this review is to provide a guide for the pathological assessment of testicular/paratesticular mesothelial tumours. Herein, we describe the most recent updates on this topic according to the latest (year 2022) World Health Organisation Classification of Urinary and Male Genital Tumours (5th edition) and current literature. The diagnostic criteria, the main differentials and the role of ancillary techniques in the diagnosis of mesothelial testicular/paratesticular tumours are discussed.

Benign Mesothelial Proliferations of the Tunica Vaginalis Testis

The correct diagnosis of mesothelial proliferations is a classic problem for pathologists, and one which has important clinical implications. A significant number of such cases appear associated with recurrent hydrocele, as an irritative/reactive response to this condition. The morphological spectrum of mesothelial lesions in this topography is broad, and a set of benign conditions may appear, sometimes with florid gross features and cytologic pseudo-atypia. Here, we present two different examples in which malignancy was initially considered in the differential diagnosis.

Well-differentiated Papillary Mesothelial Tumour of the Tunica Vaginalis Testis - A Rare Lesion, but one Pathologists Should Know About Two Patient Reports and a Review of the Literature

Besides malignant mesothelioma, benign mesothelial neoplasms do exist in the tunica vaginalis testis. However, histological criteria remain controversial, thus leading to diagnostic uncertainty and difficulty in their classification according to their biological behavior. In recent years, molecular markers have emerged that aid in the differentiation of benign and malignant mesothelial proliferations throughout the body. Here, we present two middle-aged men with well-differentiated papillary mesothelial tumors and a review of the literature. By now, more than a year after surgery, one patient showed no recurrence of disease after partial or complete orchiectomy without further treatment, for the second no information is available. In conclusion, well-differentiated papillary mesothelial tumors represent rare lesions in the tunica vaginalis testis, but one pathologists should know about to prevent unnecessary treatment and suffering of patients.

A Diagnostic Approach to Paratesticular Lesions with Tubulopapillary Architecture: A Series of 16 Serous Borderline Tumors/Low-Grade Serous Carcinoma & 14 Well-Differentiated Papillary Mesothelial Tumors and Mesothelioma

As there is limited literature on paratesticular tumors of müllerian and mesothelial origin, we reviewed archived cases of serous borderline tumors (n=15), low-grade serous carcinoma (n=1), well-differentiated papillary mesothelial tumors (WDPMT; n=2), and mesothelioma (n=12), for relevant clinicopathologic features. Molecular profiling data from the American Association for Cancer Research (AACR) GENIE registry was accessed for 8 additional patients with testicular mesothelioma. For tumors of mesothelial origin, the median age at surgical excision was 62 years, median size was 4.5 cm, and they consistently exhibited positivity for mesothelial markers (CK5/6, calretinin, WT1 and D2-40). Recurrent alterations of the NF2 gene were identified in 3 of 8 (38%) patients, and alterations of BAP1 and CDKN2A were relatively infrequent. While one patient with WDPMT had a recurrence, a second patient with WDPMT progressed to a biphasic mesothelioma two years after initial resection. For tumors of müllerian origin, the median age at surgical excision was 45 years, the median size was 2.5 cm, and these exhibited consistent positivity for ER, WT1 and PAX8. Although no recurrences were documented in patients with serous borderline tumors, a single patient with a low-grade serous carcinoma developed widely metastatic disease and died of disease-related complications. Our study emphasizes the need for close clinical follow-up in patients with WDPMT and highlights the prognostic significance of documenting invasive behavior in tumors of müllerian origin as they can have an aggressive clinical course. Finally, our results suggest that NF2 alterations may play an important role in the pathogenesis of testicular mesothelioma.

Splicing deregulation, microRNA and Notch aberrations: fighting the three-headed dog to overcome drug resistance in malignant mesothelioma

INTRODUCTION

Malignant mesothelioma (MMe) is an aggressive rare cancer of the mesothelium, associated with asbestos exposure. MMe is currently an incurable disease at all stages mainly due to resistance to treatments. It is therefore necessary to elucidate key mechanisms underlying chemoresistance, in an effort to exploit them as novel therapeutic targets.

AREAS COVERED

Chemoresistance is frequently elicited by microRNA (miRNA) alterations and splicing deregulations. Indeed, several miRNAs, such as miR-29c, have been shown to exert oncogenic or oncosuppressive activity. Alterations in the splicing machinery might also be involved in chemoresistance. Moreover, the Notch signaling pathway, often deregulated in MMe, plays a key role in cancer stem cells formation and self-renewal, leading to drug resistance and relapses.

EXPERT OPINION

The prognosis of MMe in patients varies among different tumors and patient characteristics, and novel biomarkers and therapies are warranted. This work aims at giving an overview of MMe, with a special focus on state-of-the-art treatments and new therapeutic strategies against vulnerabilities emerging from studies on epigenetics factors. Besides, this review is also the first to discuss the interplay between miRNAs and alternative splicing as well as the role of Notch as new promising frontiers to overcome drug resistance in MMe.

Molecular and Immunohistochemical Characterization of Mesothelioma of the Tunica Vaginalis

AIMS

Malignant mesothelioma (MM) of the tunica vaginalis (TV) is a rare and aggressive tumor, and the molecular features and staining profile with contemporary immunohistochemical (IHC) biomarkers are largely unexplored. We characterize the clinicopathologic, molecular, and IHC features of MM (N=13) and mesothelial neoplasms of uncertain malignant potential (MUMP) (N=4).

METHODS AND RESULTS

Targeted next-generation sequencing was performed on 7 MMs and 2 MUMPs. IHC was performed for MTAP, BAP1 and SOX6. 13 adenomatoid tumors were also assessed with SOX6. MM were epithelioid (7/13) or biphasic (6/13). In MM, NF2 (5/7; 71%), CDKN2A (3/7; 43%), and BAP1 (2/7; 29%) were most frequently altered. Non-recurrent driver events were identified in PTCH1 and TSC1. In contrast, none of these alterations were identified in MUMPs; however, one MUMP harbored a TRAF7 missense mutation. By IHC, loss of MTAP (2/12; 17%) and BAP1 (2/9; 22%) was infrequent in MM, whereas both were retained in the MUMPs. SOX6 was positive in 9/11 (82%) MMs, and negative in all MUMPs and adenomatoid tumors.

CONCLUSIONS

Testicular MM exhibit a similar mutational profile to those of the pleura/peritoneum; however, alterations in CDKN2A and BAP1 are less common. These findings suggest that although MTAP and BAP1 IHC are specific for MM, their sensitivity in testicular MMs appears lower. In addition, rare tumors may harbor targetable alterations in driver genes (PTCH1 and TSC1) that are unusual in MMs at other anatomic sites. SOX6 is sensitive for MM; accordingly, the presence of SOX6 expression argues against a benign neoplastic process.

Well-differentiated papillary mesothelioma found incidentally with concurrent struma ovarii: A case report

This is the first report of well-differentiated papillary mesothelioma (WDPM) found concurrently with struma ovarii. These rare tumors have no know association, and are considered benign, though malignant transformation of WDPM has been described. After treatment of WDPM, follow-up surveillance has been suggested in the literature, though a method has not been described and an evidence base is lacking. Pre-operative imaging by computed tomography and ultrasound did not identify the WDPM, calling into question the role of imaging-based follow-up. Furthermore, malignant transformation has been reported only outside of the typical 5-year follow-up window. The authors of this case report suggest rationalization of follow-up of WDPM, acknowledging the risks and unknown harms of scheduled imaging follow-up.

Mesothelioma of tunica vaginalis testis: A case report of two subtypes

Level of Evidence: 4

Malignant mesothelioma of the tunica vaginalis testis: a rare case and review of literature

Background

Malignant mesothelioma of the tunica vaginalis is a rare tumour which comprises less than 1% of all mesotheliomas.

Case presentation

69-years old patient with painful hard mass and hydrocele in the right scrotum to whom a right hydrocelectomy was performed. Any history of scrotal trauma or exposure to asbestos was not present. Excisional biopsy revealed a multinodular tumour with focal areas of necrosis and infiltrative growth. According to morphological and immunohistochemical findings, diagnosis of malignant biphasic mesothelioma of the tunica vaginalis testis was made. Two months after hydrocelectomy, right inguinal orchidectomy was performed. Post-surgical whole body CT scan revealed paraaortic and pararenal lymphadenopathy, likely to be metastatic. Adjuvant treatment with 6 cycles of cisplatin and pemetrexed was applied. After 3 cycles of chemotherapy, CT scan showed progression and the treatment was changed to gemcitabine 1 month after.

Conclusions

Although malignant mesothelioma of the tunica vaginalis is a rare malignancy, it poses a diagnostic challenge which can mimic common inguinal or scrotal diseases such as hydrocele. Despite aggressive surgical procedures or adjuvant therapies, the prognosis remains poor.

The necessity of a more aggressive initial surgical treatment in patients with mesothelioma of the testicular tunica vaginalis

Mesothelioma of the tunica vaginalis of the testis (MTVM) is a rare tumor encountering for less than 1% of mesothelioma. Patients suffering from these tumors have poor survival due to local and distant metastasis despite treatment. Actually, no specific treatment recommendations exist for this tumor, yet radical orchidectomy is the gold standard in limited disease. We herein report the case of a 71 patient with MTVM who underwent radical orchidectomy without inguinal lymph node dissection and recurred 2 years later with metastasis in pelvic and mediastinal lymph nodes. Despite systemic chemotherapy combining pemetrexed, bevacizumab and Cisplatinum, the disease relapsed eight months later with multiple metastatic lung nodules leading to a treatment shift. We believe that systematic inguinal-iliac lymph node resection should be included in the initial treatment of this tumor.

Asbestos exposure and malignant mesothelioma of the tunica vaginalis testis: a systematic review and the experience of the Apulia (southern Italy) mesothelioma register

BACKGROUND

Malignant mesothelioma of the tunica vaginalis testis (MMTVT) is a rare disease with a poor prognosis. The diagnosis and management of these lesions are often difficult for pathologists, surgeons, oncologists and occupational physicians. A preoperative diagnosis of malignancy is rarely made, and there is no established effective therapy except orchidectomy.

METHODS

A systematic literature review was conducted among the articles published in the English literature on primary MMTVT. Moreover four cases from the Apulia mesothelioma register are reported here.

RESULTS

Two hundred eighty-nine cases of MMTVT have been reported from 1943 to 2018. Overall asbestos exposure has been investigated only for 58% of all cases reported in this review, while in 41.8% this data are not available. Noteworthy is the fact that in many reports there is not an anamnestic reconstruction of any asbestos exposure. A history of direct occupational, environmental or familial asbestos exposure is found in 27.6% of the cases. The four cases from the Apulia mesothelioma register are all with ascertained occupational exposure to asbestos.

CONCLUSIONS

The true incidence of asbestos exposure in MMTVT is underestimated because of insufficient information reported in older literature. To establish a broad consensus on the causal relationship between asbestos and MMTVT in the scientific community its necessary to analyze the same variables in the epidemiological studies. In general it should be recommended that a positive history of exposure to asbestos or to asbestos-containing materials are at risk for the development of a MMTVT and should be monitored.

Mesothelioma subtypes of the tunica vaginalis: a rare case report and review of histological criteria

Well-differentiated papillary mesothelioma (WDPM) is a rare histological subtype of mesothelioma arising from the tunica vaginalis. We present a case of a 23-year-old male with a palpable para-testicular lump of 3 years duration. Scrotal exploration revealed a grossly abnormal cystic appearance of his tunica vaginalis. An excision biopsy confirmed WDPM of the tunica vaginalis. The three subtypes of mesothelial tumours of the tunica vaginalis are described by their distinct histological features, tumour growth and reported prognosis. A summary of immunohistochemistry and the surgical management across the disease spectrum is provided. Recent clarification of the histological criteria of WDPM provides the opportunity for surgeons to offer a limited approach to managing this indolent tumour that mimics malignant mesothelioma. However, the lack of evidence on recurrence and progression rates in WDPM restricts most surgeons to performing a radical orchidectomy, as was performed in this case.

Well-differentiated papillary mesothelioma of the peritoneum is genetically defined by mutually exclusive mutations in TRAF7 and CDC42

Well-differentiated papillary mesothelioma is an uncommon mesothelial neoplasm that most frequently arises in the peritoneal cavity of women of reproductive age. Whereas malignant mesothelioma is an aggressive tumor associated with poor outcome, well-differentiated papillary mesothelioma typically exhibits indolent behavior. However, histologically differentiating between these two entities can be challenging, necessitating the development of distinguishing biomarkers. While the genetic alterations that drive malignant mesothelioma have recently been determined, the molecular pathogenesis of well-differentiated papillary mesothelioma is unknown. Here we performed genomic profiling on a cohort of ten well-differentiated papillary mesothelioma of the peritoneum. We identified that all tumors harbored somatic missense mutations in either the TRAF7 or CDC42 genes, and lacked alterations involving BAP1, NF2, CDKN2A, DDX3X, SETD2, and ALK that are frequent in malignant mesothelioma. We recently identified that another mesothelial neoplasm, adenomatoid tumor of the genital tract, is genetically defined by somatic missense mutations in the TRAF7 gene, indicating a shared molecular pathogenesis between well-differentiated papillary mesothelioma and adenomatoid tumors. To the best of our knowledge, well-differentiated papillary mesothelioma is the first human tumor type found to harbor recurrent mutations in the CDC42 gene, which encodes a Rho family GTPase. Immunohistochemistry demonstrated intact BAP1 expression in all cases of well-differentiated papillary mesothelioma, indicating that this is a reliable marker for distinguishing well-differentiated papillary mesothelioma from malignant mesotheliomas that frequently display loss of expression. Additionally, all well-differentiated papillary mesothelioma demonstrated robust expression of L1 cell adhesion molecule (L1CAM), a marker of NF-kB pathway activation, similar to that observed in adenomatoid tumors. In contrast, we have previously shown that L1CAM staining is not observed in normal mesothelial cells and malignant mesotheliomas of the peritoneum. Together, these studies demonstrate that well-differentiated papillary mesothelioma is genetically defined by mutually exclusive mutations in TRAF7 and CDC42 that molecularly distinguish this entity from malignant mesothelioma.

Well-differentiated papillary mesothelioma: A 17-year single institution experience with a series of 75 cases

We present our experience with 75 cases of well-differentiated papillary mesothelioma (WDPM) that were diagnosed at our institution between 2000 and 2017. The patients included 58 females and 17 males with age ranging from 18 to 69 years (mean, 42 years). Clinically, the vast majority of WDPMs were incidental findings during laparotomy or laparoscopic surgery for a variety of benign or malignant disease. The lesion manifested as either a small solitary nodule or multiple miliary nodules on the peritoneum or serosal surfaces of internal organs. Histologically, 67 cases were consistent with a classical WDPM, of which 6 cases contained microinvasive foci and 1 case had malignant transformation. Eight cases were hybrid tumors with variable combined component of adenomatoid tumor (n = 4), multicystic mesothelioma (n = 2), and both (n = 2). By immunohistochemistry, besides calretinin, D2-40, CK5/6 and WT1, 94% (29/31) of cases also showed immunostaining for PAX8. In comparison, PAX8 staining was only present in 12% (6/50) of epithelioid malignant mesothelioma selected as control cases. Follow-up information available in 46 cases revealed no signs of tumor progression or local recurrence except for the case that showed transformation to a fully malignant mesothelioma after a period of 15 years. Our comprehensive study further expanded the clinical and histopathological spectrum of WDPM. Compared with epithelioid malignant mesothelioma, PAX8 staining is highly sensitive and specific for WDPM (P < 0.001).

Well-differentiated papillary mesothelioma of tunica vaginalis testis of unknown malignant potential: Sonographic appearance

Paratesticular mesothelioma is a rare differential diagnosis in the presence of scrotal hydrocele. A 17-year-old boy presented with a 3-year history of progressive hydrocele. Sonography revealed a large left paratesticular mass within the hydrocele. Serum tumor markers were negative. Left hydrocelectomy was performed and pathological analysis of the epididymal mass revealed a well-differentiated papillary mesothelioma. We discuss the sonographic and pathological findings of this rare neoplasm.

Images - Well-differentiated papillary mesothelioma of the tunica vaginalis

Well-differentiated papillary mesothelioma (WDPM) is a rare mesothelial tumour occurring in the tunica vaginalis of the testicle. The pathological classification of paratesticular mesothelial tumours is controversial and continues to evolve in the literature. Diagnostic criteria of one subtype, WDPM, are histological and include the following: 1) papillary or tubular-papillary architecture; 2) bland nuclear cytology; 3) low mitotic activity; 4) lined by a single row of cuboidal cells; and 5) absence of stromal invasion.1,2 This report presents issues of diagnosis of this rare pathology with imaging from an example case.

Epidemiology of mesothelioma of the pericardium and tunica vaginalis testis

PURPOSE

Malignant mesothelioma most commonly arises in the pleura and peritoneum but also occurs rarely at other anatomical sites with mesothelial tissue, namely, the pericardium and tunica vaginalis testis (TVT). This review provides a better understanding of the epidemiology of mesothelioma of these extrapleural sites.

METHODS

We conducted a systematic review of the epidemiologic and clinical literature on pericardial mesothelioma and mesothelioma of the TVT. We also analyzed U.S. Surveillance, Epidemiology, and End Results cancer registry data to describe incidence patterns of these malignancies.

RESULTS

An etiologic role of asbestos exposure has been hypothesized for pericardial and TVT mesotheliomas, but no analytical case-control epidemiologic studies exist to test this relationship. A substantial proportion of cases with these malignancies report no known asbestos exposure. In large occupational cohorts with heavy asbestos exposures, no cases of pericardial or TVT mesothelioma have been reported. Trends in the incidence of these malignancies do not match those of pleural mesothelioma, which correspond to historical trends of commercial asbestos use. A male preponderance of pericardial mesothelioma is not evident.

CONCLUSIONS

In the absence of analytic epidemiologic studies, the etiologic role of environmental risk factors for mesothelioma of the pericardium and TVT remains elusive.

A Case of Well-Differentiated Papillary Mesothelioma of the Male Peritoneum: Successful Treatment by Systemic Chemotherapy

Well-differentiated papillary mesothelioma of the peritoneum (WDPMP) is a rare subtype of epithelioid mesothelioma, which is usually seen in young women without a history of asbestos exposure, and generally, has an indolent course. The relative rarity of this neoplasm in males prompted us to report this case of a well-differentiated papillary mesothelioma of the peritoneum in a 36-year-old man.

The patient, who had no history of asbestos exposure, presented with abdominal pain and ascites of unknown etiology. Computed tomography showed abundant ascites with nodules of the peritoneal cavity. Laparoscopic examination revealed a large number of white miliary nodules diffusely covering the peritoneum. Pathology revealed a diagnosis of well-differentiated papillary mesothelioma of the peritoneum, based on histomorphology and immunohistochemistry. The patient started chemotherapy with cisplatin and pemetrexed. After six cycles of chemotherapy, the effectiveness of this chemotherapy was checked by only the computed tomography. PET scan was not used because it is not routinely recommended in WDPMP. Few data are currently available in the literature regarding the performance of the PET scan in WDPMP. Nine months later, the patient was free of symptoms.

Based on reviewing the literature and our observations in this case, consultation of other pathologists is highly recommended to discern WDPMP from other disseminated peritoneal diseases, in order to offer the most effective and safe therapeutic strategy. Chemotherapy should be strongly considered if the tumor is unresectable and accompanied by symptoms. Cisplatin and pemetrexed chemotherapy could be a promising therapeutic choice.

Case Report of a Well-Differentiated Papillary Mesothelioma of the Tunica Vaginalis in an Undescended Testis With Review of Literature

Well-differentiated papillary mesothelioma (WDPM) affecting the tunica vaginalis testis is a rare tumor, and very little is known about the clinicopathological spectrum of this variant as a distinct entity. Most patients with WDPM suffer from scrotal pain or swelling, but hydrocele seems to be the most common presenting symptom. These lesions are usually not aggressive and are accompanied by an indolent clinical behavior. In this article, we report the first case known of WDPM in an undescended testis, and in addition, we review the literature for similar cases.

Well-differentiated Papillary Mesothelioma of the Tunica Vaginalis

A 39-year-old man presented with painless scrotal swelling for 2 months. He denied any asbestos exposure but worked with wall and ceiling plaster. Physical exam revealed a large right scrotum which transilluminated. Scrotal ultrasonography revealed a large right hydrocele and a polypoidal mass along the anterior wall of the scrotum. Magnetic resonance imaging of the abdomen and computed tomography of the chest showed no metastases. He underwent a right inguinal scrotal exploration and wide excision of tunica vaginalis and a partial epididymectomy. Pathology revealed well-differentiated papillary mesothelioma of the tunica vaginalis. The patient had an uneventful recovery.

Well-differentiated papillary mesothelioma of the tunica vaginalis: a case study and review of the literature

Well-differentiated papillary mesothelioma is an uncommon tumor of the testes that usually presents as a hydrocele. Here, we present the case of one patient who did not have a history of asbestos exposure. The tumor was localized in the tunica vaginalis and was composed of three pedunculated masses macroscopically. Microscopically, branching papillary structures with focal coagulative necrosis were present. In addition to immunohistochemistry, simian virus 40 DNA was also tested by polymerase chain reaction. This report presents one case of this rare entity, its clinical and macroscopic features, and follow-up results.

Well-differentiated papillary mesothelioma: a clinicopathological and immunohistochemical study of 18 cases with additional observation

AIMS

To present our experience with 18 cases of well-differentiated papillary mesothelioma (WDPM), with an emphasis on its relationship to adenomatoid tumour and multicystic mesothelioma.

METHODS AND RESULTS

Eighteen cases of WDPM were retrieved. Twenty cases of multicystic mesothelioma were selected for comparative study. The WDPM patients comprised 14 females and four males, with age ranging from 18 to 60 years (median 37 years). The tumour involved the abdominal or pelvic peritoneum (14 cases), the pleura (two cases), and the testicular tunica vaginalis (two cases). The majority of WDPMs were incidental findings during surgery for a wide variety of conditions. Histologically, 13 cases were consistent with classical WDPM. Two cases had a combined component of adenomatoid tumour, and three cases contained coexisting areas of multicystic mesothelioma. Among the multicystic mesothelioma cases, four had adenomatoid tumour-like foci present in the stroma. Immunohistochemically, all cases of WDPM and multicystic mesothelioma, as well as the coexisting combined components, were positive for mesothelial markers, with a low Ki67 index. This study also showed that WDPM was negative for epithelial membrane antigen and desmin.

CONCLUSIONS

The simultaneous occurrence of WDPM, adenomatoid tumour and multicystic mesothelioma in some cases suggested histogenetic relationships among these three less aggressive mesotheliomas.

Inhalation carcinogenicity of 1,1,1-trichloroethane in rats and mice

Carcinogenicity of 1,1,1-trichloroethane (TCE) was examined by an inhalation exposure of F344 rats and BDF1 mice of both sexes to TCE at 0, 200, 800 or 3200 ppm for 6 h/d, 5 d/week for 104 weeks. In male rats, the incidences of bronchiolo-alveolar adenomas and peritoneal mesotheliomas were significantly increased in the 800 and 3200 ppm-exposed groups, respectively. The incidence of bronchiolo-alveolar adenomas in the 3200 ppm-exposed groups exceeded the range of historical control data in the Japan Bioassay Research Center. In female rats, the tumor incidences were not increased in any organs of the TCE-exposed groups. In male mice, a significant positive trend with dose was shown for incidences of bronchiolo-alveolar carcinomas, combined incidences of bronchiolo-alveolar adenomas/carcinomas and hepatocellular adenomas. The incidence of Harderian gland adenomas was significantly increased in the 3200 ppm-exposed group, and malignant lymphomas of spleen at this highest dose exceeded the range of historical control data. In female mice, the combined incidence of bronchiolo-alveolar adenomas/carcinomas was significantly increased in the 3200 ppm-exposed group, and the incidences of hepatocellular adenomas and combined incidences of hepatocellular adenomas/carcinomas were significantly increased in the 200, 800 and 3200 ppm-exposed groups with dose dependence except the combined incidence of hepatocellular adenomas/carcinomas in the 200 ppm-exposed group. The incidences of bronchiolo-alveolar adenomas in the 3200 ppm-exposed group and combined incidences of hepatocellular adenomas/carcinomas in the 200 ppm-exposed groups exceeded the ranges of historical control data. Thus, this study provided clear evidence of inhalation carcinogenicity for TCE in both rats and mice.

An unusual case of paratesticular mesothelioma on the site of previously excised epididymal adenomatoid tumour

INTRODUCTION

Malignant paratesticular tumours are rare. We report a case of paratesticular malignant mesothelioma in a patient who had excision of an adenomatoid tumour on the same site in 2 occasions previously.

PRESENTATION OF CASE

A middle aged man who had an adenomatoid tumour excised from his left hemiscrotum fifteen years previously was referred with a suspicious left epididymal lump. This was followed up sonographically for 2 years until it showed signs of enlargement and testicular invasion; it was then managed with radical orchidectomy. The histology showed paratesticular epithelioid malignant mesothelioma. The patient was referred to the Oncologists for further management.

DISCUSSION

Paratesticular tumours are commonly benign. Scrotal ultrasonography is the preferred diagnostic imaging method. Paratesticular malignant mesotheliomas are very rare and appear to have poor prognosis. The optimal adjuvant treatment post radical orchidectomy is not established yet. In our case there is suggestion of possible malignant transformation from previous adenomatoid tumour.

CONCLUSION

In recurrent paratesticular tumours the clinicians should question the possibility of malignant transformation and manage these cases accordingly.

Malignant mesothelioma of the tunica vaginalis: presenting with intermittent scrotal pain and hydrocele

Paratesticular mesotheliomas are very rare tumors. In this paper, we present the management of a 38-year-old male patient with paratesticular malignant mesothelioma who was initially misdiagnosed and treated as recurrent epididymitis. After the final pathology report defining paratesticular mesothelioma during scrotal exploration, he underwent radical orchiectomy and hemiscrotal excision as a complementary, secondary procedure. His metastatic workup did not show any dissemination. Therefore, he did not receive any adjuvant treatment and remained disease-free for more than 2 years.

Perineal and colonic metastases in two cases of malignant mesothelioma

Two patients with rare sites of metastatic pleural mesothelioma are presented and the literature on similar cases is examined. One patient developed colonic metastases from a sarcomatoid mesothelioma. Another patient with epithelioid mesothelioma developed perineal metastases.

Rare Tumors of the Testis and Mesothelial Proliferation in the Tunica Vaginalis

An increasing number of rare testicular tumors have been recognized in the recent years with a wide and heterogeneous spectrum of morphologies. The utility of ancillary studies, including immunohistochemistry, is often limited and is important for the pathologists to be aware of these entities, because they require a comprehensive pathological and clinical approach for an appropriate treatment.

Mesothelioma of tunica vaginalis of "uncertain malignant potential" - an evolving concept: case report and review of the literature

Mesothelioma of tunica vaginalis is a rare neoplasm, typically demonstrating frankly malignant morphology and aggressive behavior. Rare cases of well-differentiated papillary mesotheliomas have also been reported, which, in contrast, demonstrate indolent behavior. There are, however, cases which do not fit into the well-differentiated or diffuse malignant mesothelioma categories and can be considered mesothelioma of tunica vaginalis of "uncertain malignant potential", which is an emerging diagnostic category. A 57-year-old man presented with a neoplasm in a hydrocele sac. The neoplasm was non-invasive, but showed focal complex and solid growth and it was difficult to categorize either as well-differentiated papillary mesotheliomas or malignant mesothelioma. After the initial limited resection, the patient underwent radical orchiectomy with hemiscrotectomy and is alive and without disease progression after 6 years. Documentation of these rare tumors will allow their distinction from true malignant mesotheliomas and will facilitate the development of specific treatment recommendations.

Mesothelioma of tunica vaginalis of "uncertain malignant potential" - an evolving concept: case report and review of the literature

Mesothelioma of tunica vaginalis is a rare neoplasm, typically demonstrating frankly malignant morphology and aggressive behavior. Rare cases of well-differentiated papillary mesotheliomas have also been reported, which, in contrast, demonstrate indolent behavior. There are, however, cases which do not fit into the well-differentiated or diffuse malignant mesothelioma categories and can be considered mesothelioma of tunica vaginalis of "uncertain malignant potential", which is an emerging diagnostic category. A 57-year-old man presented with a neoplasm in a hydrocele sac. The neoplasm was non-invasive, but showed focal complex and solid growth and it was difficult to categorize either as well-differentiated papillary mesotheliomas or malignant mesothelioma. After the initial limited resection, the patient underwent radical orchiectomy with hemiscrotectomy and is alive and without disease progression after 6 years. Documentation of these rare tumors will allow their distinction from true malignant mesotheliomas and will facilitate the development of specific treatment recommendations.