Benign Cystic Mesothelioma Misdiagnosed as Peritoneal Carcinomatosis
BCM (benign cystic mesothelioma) is an uncommon benign disease characterized by multicystic tumors in the abdomen, pelvis, and retroperitoneum. It primarily affects young to middle-aged women. The majority of instances were linked to a history of abdominal or pelvic surgery, endometriosis, and pelvic inflammatory illness. We offer a unique case of BCM that differs from prior examples. On abdominal computed tomography scans, the patient was a 52-year-old man with peritoneal carcinomatosis and ascites. We present a case with BCM that was misinterpreted as peritoneal carcinomatosis.
Benign cystic mesothelioma (BCM) is a highly rare illness characterized by proliferative peritoneal mesothelial cell lesions primarily in the pelvic or abdominal cavities. It can, however, appear in the pleura, pericardium, tunica vaginalis, and spermatic cord . It has also been known as multicystic peritoneal mesothelioma, multicystic peritoneal inclusion cysts, and multicystic peritoneal inclusion cysts [1, 2]. Mennemeyer and Smith  initially described it in 1979 as a probable diagnosis in a case that resembled intra-abdominal cystic hygroma. Its etiology is still unknown, and its pathophysiology, whether reactive or malignant, is debatable.
The natural course of BCM remains unknown. Its proclivity to return following partial resection, on the other hand, has been extensively documented. There is a case report of a patient who died from the disease without therapy 12 years after being diagnosed . As a result, wherever possible, full resection is the first-line treatment. Despite the fact that intraperitoneal chemotherapy after resection has been documented as a treatment in a wide series of patients with peritoneal dissemination of appendiceal cancer, there is still debate over chemotherapy . BCM is commonly seen in women, especially those of childbearing age and with a history of endometriosis, pelvic inflammation, or abdominal surgery.
In men, the prevalence of BCM is 17% . The disease can be identified in patients who have no characteristic symptoms; nonetheless, in most cases, big masses in the abdomen are palpable, and abdominal pain is common. The authors present the case of a BCM in a 52-year-old middle-aged male patient who had ascites and was initially misdiagnosed as peritoneal carcinomatosis based on radiological evaluation.
Case Study Presentation
A 52-year-old man was admitted to our hospital after ascites were discovered during a medical checkup at a private clinic. His health state was normal at the time of admission: blood pressure 139/86 mm Hg, pulse rate 73 beats/min, respiration rate 20 beats/min, and temperature 36.5°C. He was conscious and showed no signs of the sickness. During the chest examination, the breathing and heart sounds were normal. There was some abdominal distension, but there was no increase in abdominal circumference or pain. He had no change in weight or peripheral edema of the limbs in the past few months. The peripheral blood examination revealed normal results, including leukocytes of 7,820/mm3, hemoglobins of 14.8 g/dl, and platelets of 220,000/mm3.
The findings of the biochemical tests were as follows: CRP was 0.08 mg/dl, BUN was 13.2 mg/dl, creatinine was 0.87 mg/dl, AST was 30 IU/l, ALT was 38 IU/l, total bilirubin was 0.56 mg/dl, and albumin was 4.3 g/dl. The tumor marker test revealed normal results, with -fetoprotein at 1.8 ng/ml, carcinoembryonic antigen (CEA) at 2.0 ng/ml, and carbohydrate antigen 19–9 (CA 19–9) at 11.5 U/ml. Abdominal computed tomography (CT) scans revealed moderate ascites. A mass was created by the irregularly thickened peritoneum across the abdomen and the reticular membrane in the upper left abdomen
Cystic Mesothelioma pathology outlines
Positron emission tomography of the entire body revealed no increase in the uptake of 18F-fluorodeoxyglucose. The paracentesis performed during the hospitalization yielded an erythrocyte count of 171/mm3, a leukocyte count of 288/mm3 (lymphocytes 74%), an albumin level of 2.0 g/dl, a protein level of 2.7 g/dl, and an adenosine deaminase level of 9.5 IU/l, with no MTB PCR or AFB stain. A diagnostic laparoscopy was performed because the abdomen CT scans strongly suggested peritoneal malignancy.
The laparoscopic examination revealed multiple cystic masses producing a big mass in the paracolic gutter (fig. 2a). There was a lot of yellowish ascites, and there were a lot of 2–3 mm nodules all around the abdominal cavity (fig. 2b). The vast reticular membrane was adhering to the pelvic wall. A biopsy was done, yielding tissue measuring 2 1.5 mm from the reticular membrane. The biopsy revealed numerous cysts of varying sizes surrounded by flat cubic epithelial cells.
Benign cystic mesothelioma treatment
The staining was done using immunohistochemistry. The patient was diagnosed with BCM because the biopsy did not stain for CD31 but did strongly stain for calretinin and D2–40 (fig. 3b). The patient was informed about the possibility of malignancy and was advised to have a radical excision performed, but he chose to wait because the symptoms were not yet obvious. Two months later, we performed an abdominal CT scan. We advised surgical treatment because the lesion had not changed and there was still ascites. However, he continued to refuse it, so we decided to keep an eye on the situation.
Findings from laparoscopy. In front of the paracolic gutter space, variable-sized multicystic masses can be noticed. b In the peritoneal cavity, there were several 2- to 3-mm-sized nodular lesions that seemed to be peritoneal seeding masses.
Cystic Mesothelioma Discussion
Although Plaut  first mentioned BCM in 1928, it was suggested that it originated in mesothelial cells owing to electron microscope discoveries by Mennemeyer and Smith . After that, the sickness could be diagnosed once it was distinguished from other ailments. BCM was detected after the debut of immunohistochemistry when it was stained for both calretinin and D2-49 at the same time.
BCM is known to occur in women of childbearing age. According to a research on the analysis of 37 patients with BCM, 83.8 percent of the patients were female, with an average age of 38 years. Because the condition is identified in 37.8 percent of participants in their 50s, 5.3 percent of adults in their 60s, 10.8 percent of subjects in their 70s, and infants, it is thought that BCM can occur at any age. It is known to be more common in people with a history of endometriosis, pelvic inflammation, and abdominal surgical treatment, notably in hysterectomy and cesarean section patients .
BCM is a type of tumor that develops from mesothelial cells in the peritoneum, pleura, and pericardium. It can also occur in the groin and scrotum, which are peritoneal extensions. Patients with BCM in the groin and scrotum might detect palpable masses on their own and, as a result, present to the hospital earlier . BCM in the abdominal or pelvic cavities, on the other hand, is difficult to detect until the mass is large.
BCM is especially difficult to diagnose in our instance because it is uncommon in a middle-aged man, and there were no distinctive signs such as palpable mass or abdominal distension. So far, only 5 instances of BCM with ascites have been reported worldwide . His serum-ascites albumin gradient (SAAG) was 2.3 g/dl, and his protein level was 2.7 g/dl, indicating that the condition was caused by cardiac ascites. As a result, as more data concerning BCM with ascites becomes available in the future, the unique characteristics of ascites in BCM could be examined.
BCM is classified into three forms according on its shape: (1) solitary when the boundary is obvious, (2) localized when many masses are discovered in a confined region of the abdominal membrane, and (3) diffuse when the masses are extensively scattered across the abdominal membrane . The best treatment is surgical removal. To avoid recurrence and progression to malignancy, it is best to excise a large enough region whenever possible .
Only two cases of BCM developing into cancer were reported worldwide: a newborn at the age of six months and a female at the age of 36 years [9, 10]. As a result, because the rate of transition to malignancy is so low, re-excision is frequently performed even for local recurrence. Attempts to employ hot intraperitoneal chemotherapy in the abdominal cavity have been made in a few trials, although this is still in the experimental stage .
benign cystic mesothelioma symptoms conclusion
BCM is an extremely rare disease that primarily affects women of childbearing age. We presented a male patient with widespread BCM and ascites who had previously been misdiagnosed with peritoneal carcinomatosis.