Benign multicystic peritoneal mesothelioma occurring in bilateral inguinal canals metachronously: a case report
Hiroyuki Oshikiri1,2, Yohei Ozawa3, On Suzuki4
1Department of Digestive Surgery, Iwate Prefectural Central Hospital, 1-4-1, Ueda, Morioka, Iwate, 020-0066, Japan. h-oshikiri@med.tohoku.ac.jp.
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.
Insights
This case study reports the first instance of benign multicystic peritoneal mesothelioma (BMPM) occurring in both inguinal canals of a middle-aged female. Surgical resection is the recommended treatment for this rare tumor, with immunohistochemistry aiding diagnosis.
Area of Science:
- Oncology
- Pathology
- Surgical Case Reports
Background:
- Benign multicystic peritoneal mesothelioma (BMPM) is a rare benign tumor typically affecting middle-aged females.
- While commonly found in the abdominal cavity, BMPM in the inguinal region is infrequently documented.
Purpose of the Study:
- To report the first case of metachronous benign multicystic peritoneal mesothelioma in bilateral inguinal canals.
- To highlight diagnostic and therapeutic considerations for inguinal BMPM.
Main Methods:
- A 48-year-old female presented with inguinal masses, initially suspected as hernia or hydrocele.
- Surgical resection and mesh plug hernia repair were performed for both left and right inguinal tumors.
- Pathological examination, including immunohistochemistry for calretinin and D2-40, confirmed BMPM in both instances.
Main Results:
- The first inguinal BMPM measured 80 mm; the second, occurring 5 years later, measured 45 mm.
- Immunohistochemistry confirmed BMPM in both resected tumors.
- No recurrence was observed 33 months after the second surgery.
Conclusions:
- This is the first reported case of bilateral metachronous inguinal BMPM.
- Surgical resection is the primary treatment for inguinal BMPM.
- Pathological examination with immunostaining is crucial for diagnosis; further case accumulation is needed for optimal follow-up strategies.
