Benign multicystic peritoneal mesothelioma: literature review and update

Abstract

Benign multicystic peritoneal mesothelioma (BMPM) is a rare peritoneal tumor diagnosed predominantly in pre-menopausal women. Associated risk factors include endometriosis and pelvic inflammatory disease in women, and prior abdominal surgery in both genders. To date, the pathogenesis of this disease remains controversial with possible etiologies, including a neoplastic versus a reactive process. Given the risk factors, some authors believe that this disease is secondary to a reactive process. However, because some studies describe cases where there is no prior surgical history or inflammatory milieu present, and because of this entity's predilection for recurrence, some authors believe the origin to be neoplastic. Some genetic and familial associations have also been reported. Malignant transformation is extremely rare, with only two cases reported in the literature, despite the recurrence potential. Like the etiology, the name of this entity is also controversial. Some authors prefer the term "peritoneal inclusion cyst (PCM)" instead of "benign cystic mesothelioma" and argue that the term mesothelioma should only be used when there is evidence of atypia. Most cases of BMPM are discovered incidentally. Others reflect sequela of tumor mass effect. It appears intra-operatively as large, multi-focal, cystic lesions in the peritoneal and pelvic cavity. Diagnosis is achieved through surgical sampling with histopathological examination. Immunobiologically, BMPM exhibits multiple small cystic spaces with flattened lining containing calretinin positive cells without atypical features, mitotic figures, or tissue invasion. Treatment includes cytoreductive surgery. Here we present a case of BMPM in a 60-year-old male - a rare disease in an uncommon patient population.

Keywords: Asbestos; BAP1 protein; Cystic Lymphangioma; Cystic Mesothelioma; Mesothelioma; human.

Figure 1. Abdominal contrast-enhanced CT scan of BMPM. A – Axial Post-Contrast CT demonstrating cystic lesion posterior to the urinary bladder; B – Axial Post-Contrast CT demonstrating cystic lesion in the right para-colic gutter; C – Sagittal Post-Contrast CT demonstrating cystic lesion posterior to the urinary bladder; D – Coronal Post-Contrast CT demonstrating cystic lesion in the right para-colic gutter

Figure 2. Intraoperative images showing multicystic, grapelike masses.

Figure 3. Photomicrograph of the surgical specimen showing in A – numerous variably sized cystic spaces (H&E-Low power magnification); B – Higher magnification showing mesothelial cells lining the cysts (H&E, 400X).

Figure 4. Photomicrograph of the surgical specimen showing in A and B – Calretinin immunohistochemical staining (×400) reveals a positive reaction.