Primary pericardial mesothelioma (PPM) is an exceedingly rare malignant cancer accounting for only 0.7% of all malignant mesotheliomas, with an annual standardized incidence rate of approximately 0.36 per 10 million person-years (1–5). PPM has a poor prognosis with a median survival of less than six months (1, 4–6), which has been partly attributed to its frequently delayed diagnosis (6–8). In many PPM cases, the time from presentation to definite diagnosis may last for several months (4–7) or even over one year (6, 9–14). This slow recognition is likely due to its nonspecific syndromes, its similar presentation to benign pericardial diseases, and its non-definitive etiology (1, 6–8, 10–15). It has been suggested that early detection of this disease is the only hope for survival (2). Unlike pleural mesothelioma, the relationship between PPM and asbestos exposure remains unsettled; some investigators reported an association with asbestos exposure (3, 4, 16), while others reported no or weak correlation (6–10, 12–15, 17–19). So far, there is no consensus on the treatment of PPM, although the survival benefit of chemotherapy has been shown to be superior to that of surgery (6). In almost all reported cases with chemotherapy, a doublet regimen, cisplatin plus pemetrexed, was used as the first-line treatment (6, 7, 9–11, 17, 18, 20, 21). Here we present a case of early diagnosis of PPM promoted by the indication of the patient's occupational asbestos exposure history and clinical presentations. This patient was subsequently treated with bevacizumab (a humanized anti-VEGF antibody) (2) combined with first-line chemotherapy.

This report describes a patient with PPM who had an occupational long-term asbestos exposure history and who received chemotherapy only after diagnosis resulting in satisfactory outcomes. In this case, early diagnosis of PPM and bevacizumab-based chemotherapy are two main points that deserve to be highlighted.

Our patients underwent a total of 6 cycles of chemotherapy in the first course with a combination of bevacizumab as the first-line treatment, resulting in complete relief of symptoms and satisfactory outcomes. This choice was made based on the patient's preference for palliative chemotherapy over surgical intervention following a full discussion of treatment plans. Due to its rarity, there is no consensus on the treatment of PPM (1, 2, 5, 6). Currently, treatment options for PPM are adapted from the more often studied diffuse pleural mesotheliomas (1, 2, 18); surgery is the most widely-used approach, followed by chemotherapy (5, 6, 18). However, in a review of 103 published PPM cases, it was found that chemotherapy, but not surgery, provided a statistically significant survival benefit. Of note, a doublet regimen, cisplatin plus pemetrexed, was used as the first-line treatment in almost all reported cases with chemotherapy (6, 7, 9–11, 17, 18, 20, 21). In only one reported case (14), a combination of bevacizumab, cisplatin, and pemetrexed was used as the first-line treatment for PPM, but unfortunately, the tumor remained stable after eight cycles of chemotherapy. Bevacizumab is a humanized anti-VEGF antibody that inhibits angiogenesis (2). In our case, the patient well tolerated the first course of chemotherapy in combination with bevacizumab with a satisfactory outcome. Unfortunately, the patient opted to discontinue the medical treatment after the initiation of the second course and subsequently expired. The use of bevacizumab has been shown to be promising in the treatment of malignant pleural mesothelioma (22). The addition of bevacizumab to standard-of-care chemotherapy has provided a novel therapeutic option in a range of advanced cancers (23). Several randomized controlled trials have been conducted to investigate its efficacy in different types of cancers, including colorectal cancer, lung cancer, breast cancer, renal cell carcinoma, cervical cancer, glioblastoma, and ovarian cancer (23). In light of this fact, we still suggest that bevacizumab may also be considered as an option for the treatment of PPM.

The diagnosis of PPM remains challenging, which leads to the situation that the diagnosis is usually made after surgery or at autopsy (2, 10, 15, 18, 21). The delayed diagnosis of PPM may be due to its nonspecific syndromes, its similar presentation to benign pericardial diseases, and its non-definitive etiology (1, 6–8, 10–15). Our patient also initially had nonspecific symptoms and inconclusive image findings. However, the occupational long-term asbestos exposure history of this patient raised our concerns regarding potential malignancy when confronted with unexplained pericardial effusion accompanied by cardiac tamponade. As a result, from the time of admission, it only took 11 days for us to establish a definitive diagnosis. The etiology of PPM is unclear. The relationship between PPM and asbestos exposure remains controversial (3, 4, 6–10, 12–19). Our finding regarding the early detection of PPM supports the notion that asbestos exposure plays a role in the pathogenesis of PPM. Although the mechanisms underlying this pathogenesis remain unclear, it has been proposed (24) that, after asbestos fibers are inhaled deeply into the lung and penetrate the pleural space, the interaction of asbestos fibers with mesothelial cells and inflammatory cells is thought to initiate prolonged cycles of tissue damage, repair, and local inflammation, which finally lead to carcinogenesis of malignant mesothelioma.

In conclusion, we present a case of an early multidisciplinary clinical approach to diagnose and manage PPM with consideration of occupational asbestos exposure history and clinical symptoms. Although the patient expired after the premature discontinuation of the second course of chemotherapy based on the patient's own decision, bevacizumab-based chemotherapy remains an option for the treatment of PPM.