Malignant Mesothelioma of the Tunica Vaginalis: A Rare Neoplasm—Case Report and Literature Review

A rare presentation of malignant mesothelioma of the tunica vaginalis managed with immunotherapy and review of the literature

Key Clinical Message

We describe the first case in literature of malignant mesothelioma of the tunica vaginalis that has shown partial response to systemic immunotherapy (ipilimumab-nivolumab) post orchiectomy, warranting further investigation in a trial setting.

Abstract

We present a case report of an 80-year-old ex-smoker with a rare diagnosis of metastatic mesothelioma of the tunica vaginalis, managed with immunotherapy. The patient, with no known history of asbestos exposure, presented with a left scrotal mass and pain. Scrotal ultrasound confirmed a large paratesticular mass, and computed tomography (CT) of the chest, abdomen, and pelvis revealed a bilobed mass in the left scrotal compartment without associated inguinal or abdominopelvic lymphadenopathy, and an indeterminate, subcentimeter, bi-basal subpleural nodules. He underwent a left orchiectomy, and histopathology confirmed the diagnosis of a paratesticular mesothelioma. Postoperatively, the patient had a positron emission tomography (PET) scan showing a new right pleural effusion as well as increasing size of the lobar and pleural nodules bilaterally, all metabolically active and suggestive of progressive metastatic disease. The patient was commenced on ipilimumab and nivolumab immunotherapy, a regimen indicated for malignant pleural mesothelioma; however, the efficacy on paratesticular mesothelioma is not known. After 6 months of treatment, the patient demonstrated a partial response to immunotherapy, with a reduction in the size of known pleural nodules and effusion.Literature review suggests that diagnosis requires a high index of suspicion and patients commonly have metastatic disease at the time of diagnosis. Orchiectomy is a common management modality. However, the role, regimen, and benefits of systemic therapy are unclear, warranting further studies investigating management strategies.

Define the Two Molecular Subtypes of Epithelioid Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a fatal disease of respiratory system. Despite the availability of invasive biomarkers with promising results, there are still significant diagnostic and therapeutic challenges in the treatment of MPM. One of three main mesothelioma cell types, epithelioid mesothelioma makes up approximately 70% of all mesothelioma cases. Different observational findings are under process, but the molecular heterogeneity and pathogenesis of epithelioid malignant pleural mesothelioma (eMPM) are still not well understood. Through molecular analysis, expression profiling data were used to determine the possibility and optimal number of eMPM molecular subtypes. Next, clinicopathological characteristics and different molecular pathways of each subtype were analyzed to prospect the clinical applications and advanced mechanisms of eMPM. In this study, we identified two distinct epithelioid malignant pleural mesothelioma subtypes with distinct gene expression patterns. Subtype I eMPMs were involved in steroid hormone biosynthesis, porphyrin and chlorophyll metabolism, and drug metabolism, while subtype II eMPMs were involved in rational metabolism, tyrosine metabolism, and chemical carcinogenesis pathways. Additionally, we identified potential subtype-specific therapeutic targets, including CCNE1, EPHA3, RNF43, ROS1, and RSPO2 for subtype I and CDKN2A and RET for subtype II. Considering the need for potent diagnostic and therapeutic biomarkers for eMPM, we are anticipating that our findings will help both in exploring underlying mechanisms in the development of eMPM and in designing targeted therapy for eMPM.

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.

Scientific Advances and New Frontiers in Mesothelioma Therapeutics

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that arises from the mesothelial surface of the pleural and peritoneal cavities, the pericardium, and rarely, the tunica vaginalis. The incidence of MPM is expected to increase worldwide in the next two decades. However, even with the use of multimodality treatment, MPM remains challenging to treat, with a 5-year survival rate of less than 5%. The International Association for the Study of Lung Cancer has gathered experts in different areas of mesothelioma research and management to summarize the most significant scientific advances and new frontiers related to mesothelioma therapeutics.

Asbestos Exposures, Mesothelioma Incidence and Mortality, and Awareness by General Practitioners in the Molise Region, Central Italy

OBJECTIVE

The aim of this study was to evaluate environmental asbestos sources, mesothelioma incidence and mortality, and awareness on asbestos-related diseases (ARDs) by general practitioners (GPs) in Molise Region.

METHODS

The contaminated sites in three towns were identified by census; mesothelioma incidence (2000 to 2012) and mortality (2003 to 2013) was achieved from local registries; GPs were interviewed on practiced population's exposures and ARDs diagnosis.

RESULTS

About 54.3% of visited sites were contaminated (71.2% by friable asbestos) and 38.8% was extremely damaged. Over above time-periods, 32 mesothelioma cases (62.5% males, 25% in people aged 70 to 75 years) and 27 deaths (90% males, 69 ± 10 years, 70.4% pleural mesothelioma) have been reported. A total of 122 GPs were interviewed who had diagnosed 40 mesothelioma and 28 asbestosis cases.

CONCLUSION

There is the need of remediation/removal interventions for contaminated sites and of strategies to increase GPs awareness on asbestos risks for better patients' management.

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.

The legacy of the F344 rat as a cancer bioassay model (a retrospective summary of three common F344 rat neoplasms)

The Fischer 344 (F344) rat was used by the National Toxicology Program (NTP) for over 5 decades for toxicity and carcinogenicity studies. However, in 2006, the NTP decided to switch to a different rat stock due largely to high background control incidences of Leydig cell tumors (LCTs) and mononuclear cell leukemia (MNCL), also known as large granular lymphocytic (LGL) leukemia. In the current review, we aim (1) to provide a summary of NTP bioassays with treatment-associated effects involving MNCL and LCTs in addition to male F344-specific tunica vaginalis mesothelioma (TVM); (2) to describe important pathobiological differences between these F344 rat tumor responses and similar target tissue-tumor response in humans; and (3) to present the NTP reasons for switching away from the F344 rat. We show that due to the highly variable background incidence of F344 MNCL, more reliance on historical control data than is usual for most tumor responses is warranted to evaluate potential effect of any chemical treatment in this rat strain. The high spontaneous incidence of LCTs in the testes of male F344 rats has made this tumor endpoint of little practical use in identifying potential testicular carcinogenic responses. TVM responses in F344 rats have a biological plausible relationship to LCTs unlike TVM in humans. Given their high spontaneous background incidence and species-specific biology, we contend that MNCL and LCT, along with TVM responses, in F344 rat carcinogenicity studies are inappropriate tumor types for human health risk assessment and lack relevance in predicting human carcinogenicity.