Benign multicystic peritoneal mesothelioma occurring in bilateral inguinal canals metachronously: a case report

Abstract

Background Benign multicystic peritoneal mesothelioma (BMPM) is a benign tumor that usually occurs in middle-aged females. Although several published studies have reported the occurrence of this tumor in the abdominal cavity, few have documented its development in the inguinal region. Case presentation We present a case of a 48-year-old female presenting with a bulge in her left inguinal region. Physical examination revealed a golf ball-sized nodule in the left inguinal region that could not be pushed back into the abdominal cavity. Contrast-enhanced computed tomography showed a multicystic tumor; therefore, the patient was diagnosed with inguinal hernia or hydrocele of the Nuck’s canal. We performed surgical resection and hernia repair using the mesh plug method. The resected specimen was 80 mm in length and contained a multicystic tumor. Pathological examination showed that the cyst wall was lined by a single layer of cuboidal to single layer squamous epithelium. Immunohistochemistry revealed positivity for calretinin in the epithelial cells, for which a diagnosis of BMPM was established. The patient returned to our hospital after 5 years with symptoms similar to the previous episode, but this time in the right inguinal region. Imaging studies showed a tumor in the right inguinal region with the same characteristics as the previous one. The patient underwent tumor resection and hernia repair using the same technique. The resected tumor was 45 mm in length and had characteristics similar to the previously resected tumor. The presence of calretinin and D2-40 on immunohistochemistry led to the diagnosis of BMPM. There was no recurrence of BMPM for 33 months after the secondary surgery. Conclusions Here we present the first report of metachronous BMPM occurring in bilateral inguinal canals. Although the pathogenesis of BMPM remains unclear, reactive changes have been suggested to cause tumors originating from the groin. The treatment of choice for BMPM is surgical resection. For diagnosis, pathological examination with immunostaining can be useful. The most appropriate postoperative follow-up for inguinal BMPM is controversial, and the accumulation of more inguinal BMPM cases is needed.

Benign multicystic peritoneal mesothelioma mimicking mucinous ovarian neoplasm with pseudomyxoma peritonei

“…This chronic irritation causes alterations in mesothelial cells such as cell entrapment, reactive proliferation, metaplasia and cystic formation 6 8. There are some studies showing that 30%–87% of patients who develop BMPM have had previous abdominal surgery 8. These studies support the first hypothesis which is the most widely accepted 6.…”

“…However, there are three proposed hypotheses for the pathophysiology 6. First, BMPM is usually considered a peritoneal reaction secondary to chronic irritation 8. This chronic irritation causes alterations in mesothelial cells such as cell entrapment, reactive proliferation, metaplasia and cystic formation 6 8.…”

“…First, BMPM is usually considered a peritoneal reaction secondary to chronic irritation 8. This chronic irritation causes alterations in mesothelial cells such as cell entrapment, reactive proliferation, metaplasia and cystic formation 6 8. There are some studies showing that 30%–87% of patients who develop BMPM have had previous abdominal surgery 8.…”

“…The present case also had a history of total abdominal hysterectomy for myoma uteri and it supports this hypothesis. Second, some researchers consider BMPM as neoplastic peritoneal serosa lesions because some BMPM patients have no history of abdominal surgery or endometriosis 6 8. Lastly, there is a hormonal hypothesis supporting that BMPM is associated with sex hormone sensitivity because BMPM is generally seen in women of reproductive age, especially in those who have a history of endometriosis and it has responsiveness to endocrine drugs, such as tamoxifen 2 6.…”

“…Besides, they can cause non-specific abdominal pain and discomfort, bloating, constipation, deep pelvic pain, dyspareunia, incontinence and anorexia if their sizes increase 2. Considering that BMPM is often found in the pelvis, it is difficult to differentiate from other pelvic and abdominal lesions, such as cystic lymphangioma, cystic adenomatoid tumours, malignant peritoneal mesothelioma, mesenteric and omental cysts, cystic endosalpingiosis and cystic ovarian masses, especially mucinous cystadenoma–adenocarcinoma, pseudomyxoma peritonei, endometriosis or peritoneal hydatidosis 1 2 5–9. Although there is no evidence-based guideline for treatment, it is usually considered that surgical resection with hyperthermic intraperitoneal chemotherapy (HIPEC) is the best option 6.…”