Benign Cystic Mesothelioma Misdiagnosed as Peritoneal Carcinomatosis

Large and Extensive Multilocular Peritoneal Inclusion Cysts Lack Genomic Alterations and Follow an Indolent Clinical Course Despite Rare Recurrences

Peritoneal inclusion cysts (PICs) are unilocular or multilocular cystic lesions lined by bland mesothelial cells. While most are small and localized, rare examples may be large or multifocal with diffuse peritoneal involvement, causing clinical and even pathologic concern for malignancy. We examined 20 PIC, including 8 large solitary and 12 multifocal lesions. Solitary PIC were found in 7 female and 1 male patients ranging from 19 to 55 (median: 37) years. Expanded collagenous (n=2) or edematous (n=1) areas were occasionally seen in the septae, and 1 had microscopic foci of myxoid stroma. Four had hobnail cells, and 1 had minor areas of papillary mesothelial hyperplasia. Multifocal PICs occurred in 9 female and 3 male patients ranging from 26 to 80 (median: 53) years. Three showed extensive associated fibrosis with entrapment of preexisting adipose tissue, 2 had areas resembling granulation tissue, and 3 had scattered foci of myxoid stroma. Hobnail cells were present in 9, papillary mesothelial hyperplasia in 2, entrapped single cells in 1, and 2 had areas resembling adenomatoid tumors. Two of the multifocal PICs had limited local recurrences at 18 and 21 months. No patients died of disease. Clonal alterations were not identified in any of the tested PICs (mutational and fusion analysis in 5, chromosomal microarray in 1). Despite limited local recurrences, we demonstrate that even large and multifocal PICs may lack identifiable genomic alterations and are associated with benign outcomes.

A colic mesothelial cyst, mimicking an appendicular mucocoele in an elderly patient: A case report and a literature review

ABSTRACT

Benign cystic mesothelioma is a very rare and uncommon lesion, first reported by Plaut in 1928. It affects young women of reproductive age. It is usually asymptomatic or has non-specific symptoms. Diagnosis remains difficult despite the evolution of imaging, and the histopathological study is the key examination to make the diagnosis. Surgery remains the only curative treatment, regardless of significant rate of recurrence, and until today, no consensus on the therapeutic strategy is established.

BENIGN MULTICYSTIC PERITONEAL MESOTHELIOMA MIMICKING GYNECOLOGIC PATHOLOGY

Benign multicystic peritoneal mesothelioma is a rare pathology that arises from the abdominal peritoneum. It has an affinity to develop on the surfaces of pelvic viscera. It predominantly occurs in women of reproductive age. The most used form of treatment is complete surgical removal. We report a case of a a 21-year-old female patient who presented with unclear diffuse abdominal pain. Transvaginal ultrasound and magnetic resonance imaging of the abdomen and pelvis revealed multiple functional cysts in the projection of the right and left ovary and free fluid in the pouch of Douglas. Laparoscopy was performed and multicystic tumor with thin, smooth walls, filled with clear serous content was found in lesser pelvis spreading to the left paracolic region and under the spleen. The multicystic mass was removed. Histologic examination revealed cystic formations filled with mucous content and formed from connective tissue outside and single row epithelium-mesothelium inside. Definitive diagnosis was benign multicystic mesothelioma of the abdominal peritoneum. The patient was well at one year follow-up.

Pre-clinical Models for Malignant Mesothelioma Research: From Chemical-Induced to Patient-Derived Cancer Xenografts

Malignant mesothelioma (MM) is a rare disease often associated with environmental exposure to asbestos and other erionite fibers. MM has a long latency period prior to manifestation and a poor prognosis. The survival post-diagnosis is often less than a year. Although use of asbestos has been banned in the United States and many European countries, asbestos is still being used and extracted in many developing countries. Occupational exposure to asbestos, mining, and migration are reasons that we expect to continue to see growing incidence of mesothelioma in the coming decades. Despite improvements in survival achieved with multimodal therapies and cytoreductive surgeries, less morbid, more effective interventions are needed. Thus, identifying prognostic and predictive biomarkers for MM, and developing novel agents for targeted therapy, are key unmet needs in mesothelioma research and treatment. In this review, we discuss the evolution of pre-clinical model systems developed to study MM and emphasize the remarkable capability of patient-derived xenograft (PDX) MM models in expediting the pre-clinical development of novel therapeutic approaches. PDX disease model systems retain major characteristics of original malignancies with high fidelity, including molecular, histopathological and functional heterogeneities, and as such play major roles in translational research, drug development, and precision medicine.

Benign multicystic mesothelioma and peritoneal inclusion cysts: are they the same clinical and histopathological entities? A systematic review to find an evidence-based management

PURPOSE

Peritoneal mesothelial cysts (PMC) are a clinical dilemma because of their true pathogenic nature. Many definitions have been associated with PMC, including "benign multicystic mesothelioma", "cystic mesothelioma", "multilocular peritoneal inclusion cysts", ''inflammatory cysts of the peritoneum" or "postoperative peritoneal cyst".

METHODS

We herein performed a systematic review of the literature focusing on clinical and histopathological aspects of PMC, diagnosis, and therapies. Moreover, we described our experience with a case of PMC in a young female.

RESULTS

Since there is often a history of prior surgery or inflammatory disease, most authors consider PMC of reactive origin. However, in some cases they occur without any documentable signs of disease or injury. A variety of clinical findings can complicate the preoperative assessment and a multitude of histological pictures may potentially lead to a misdiagnosis. The absence of a uniform treatment strategy and lack of long-term follow-up often hinder the accurate definition leading to unnecessary or unnecessarily aggressive therapy.

CONCLUSIONS

PMC are more common than had previously been thought. Most authors consider them non-neoplastic; thus the designation of "peritoneal inclusion cyst" is preferable. The term "mesothelioma" should be used only in cases of histological evidences of atypia. The high rates of recurrence suggest that the goal of treatment should not be necessarily complete eradication, but symptomatic relief through individualized treatment. This is a topic of particular importance, especially in young female where recurrence rates could be lower than those reported in adults and where an improperly aggressive treatment could have repercussions on fertility.

Benign multicystic peritoneal mesothelioma treated with laparoendoscopic single site surgery: a case report and review of the literature

Benign multicystic peritoneal mesothelioma (BMPM) is rare and difficult to diagnose before surgery. We report a case of BMPM incidentally discovered during laparoendoscopic single site surgery (LESS) for treatment of a pelvic mass. A 47-year-old Korean menopaused woman presented to our outpatient clinic with a pelvic mass. She had a history of right ovary cystectomy with adhesiolysis at a local hospital in 2010. Imaging study of the pelvis revealed a multilocular cystic mass. LESS was performed and multiple grapelike clusters of cysts were seen in the uterus, cul-de-sac, both adnexa, pelvic wall, and omentum. The appendix was grossly free. Frozen biopsy confirmed BMPM. Excision of multiple cyst clusters of cysts, resection of the uterus with both adnexa, appendectomy, omentectomy, and adhesiolysis were performed with LESS. She is well for 2 years with no recurrence. BMPM should be included in the differential diagnosis when small multichamber cystic mass is found on ultrasonography.

The first case of benign multicystic mesothelioma presenting as a splenic mass

Multicystic mesothelioma (MM) is a relatively rare tumour arising in the pelvic peritoneum of the tuboovarian region of young woman. Exceptionally, MM occurs on the serosal surfaces of various organs including kidney, bladder, lymph nodes, and liver. We report here the first case of MM wherein a 58-year-old woman with a previous history of endometriosis of the right ovary presented with a large multicystic mass of the spleen. The diagnosis of MM was made on a surgical specimen after splenectomy. A histopathologic examination is always necessary for the diagnosis of MM which should be differentiated from other lesions particularly from cystic lymphangioma. At one year follow-up, the patient had no evidence of recurrence. Despite the high frequency of local recurrences, MM is a benign lesion and ‘en bloc’ surgical excision with prolonged follow-ups is the treatment of choice.