Malignant peritoneal mesothelioma in childhood with long-term survival

Molecular characterization of diffuse malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma is a rare aggressive tumor that arises from the peritoneal lining. While recurrent BAP1 mutations have been identified in a subset of mesotheliomas, molecular characteristics of peritoneal mesotheliomas, including those lacking BAP1 alterations, remain poorly understood. Using targeted next-generation sequencing, we examined the molecular features of 26 diffuse malignant peritoneal mesotheliomas. As part of an exploratory analysis, we analyzed an additional localized peritoneal mesothelioma and one well-differentiated papillary mesothelioma with invasive foci. Genomic characterization identified categories of diffuse malignant peritoneal mesotheliomas: The first group included 18 (69%) tumors with recurrent BAP1 alterations, with eight (31%) having more than one BAP1 alterations, and concomitant alterations in PBRM1 (46%) and SETD2 (35%). All tumors with complete loss of BAP1 expression by immunohistochemistry harbored BAP1 molecular alterations. PBRM1 alterations were significantly enriched in the BAP1-altered cohort. Frequent copy number loss of BAP1, ARID1B, PRDM1, PBRM1, SETD2, NF2, and CDKN2A was noted. The second group included eight (31%) BAP1-wild-type tumors: two with TP53 mutations, one with a TRAF7 activating mutation, one with a SUZ12 inactivating mutation, and three with ALK rearrangements that we previously published. One TP53-mutant biphasic mesothelioma showed evidence of genomic near-haploidization showing loss of heterozygosity of all chromosomes except 5, 7, 16, and 20. The localized peritoneal mesothelioma harbored a nonsense CHEK2 mutation, and the well-differentiated papillary mesothelioma with invasive foci harbored no reportable variants. In conclusion, we described the genetic categories of diffuse malignant peritoneal mesotheliomas, with BAP1-mutant and BAP1-wild-type groups. Our findings implicated DNA repair, epigenetics, and cell cycle regulation in the pathogenesis of peritoneal mesotheliomas, with identification of potential therapeutic targets.

Primary malignant mesothelioma of the peritoneum: a clinical and immunohistochemical study

BACKGROUND

Primary peritoneal mesothelioma is regarded as a fatal disease that presents with progressive ascites at a relatively late stage of its natural history. Differential diagnosis between this rare tumor and both serous papillary carcinoma of the peritoneum and ovary can be problematic.

CASE

A 54-year-old woman presented to our institution with a 4-month history of dull epigastric pain and increased abdominal girth. Exploratory laparotomy revealed the presence of extensive intraperitoneal dissemination of a malignant neoplasm without a recognizable primary site. Suboptimal cytoreduction was carried out, and histological diagnosis was that of a malignant epithelioid mesothelioma. This was confirmed with a panel of immunohistochemical markers. The patient despite having a complete response after adjuvant chemotherapy died 18 months after primary surgery.

CONCLUSION

No single immunohistochemical stain is pathognomonic of peritoneal primary malignant mesothelioma (PMM), and the results of a panel of antibodies should be interpreted to set the diagnosis.

An autopsy case of a malignant pericardial mesothelioma in a Japanese young man

An autopsy case of a malignant pericardial mesothelioma in a 27-year-old man with no history of exposure to asbestos is reported. He was admitted for heart failure due to pericardial effusion of unknown origin and surgically drained, but later died. The diagnosis of a malignant pericardial mesothelioma was made on the basis of histologic, immunohistochemical and ultrastructural findings. The tumor was located on the pericardium, but autopsy revealed that it had spread extensively in the mediastinum and the lungs. Microscopically, the tumor cells were epithelial like and contained histochemically demonstrable glycogen and hyaluronic acid. Immunohistochemical studies of the tumor demonstrated positive immunoreactivity for cytokeratin 19, muscle actin HHF35, epithelial membrane antigen, CA125, p53 and p21WAF1/CIP1 whereas the tumor was negative for cytokeratins 10 and 17, carcinoembryonic antigen, vimentin, epithelial antigen BerEP4, S-100, c-erbB2 and bcl-2. A high MIB-1 labeling index was noted. Under the electron microscope the tumor cells exhibited long, thin villi. The operation and autopsy findings thus revealed this to be a very rare case of malignant pericardial mesothelioma in a young man.

Malignant mesotheliomas presenting as ovarian masses. A report of nine cases, including two primary ovarian mesotheliomas

Nine cases of malignant mesothelioma (MM) presenting as ovarian masses occurred in female patients aged 16 to 63 (median, 52) years. In most of the cases, the referring pathologist initially misdiagnosed the neoplasm or was uncertain about its nature. In two cases, the tumors were confined to one or both ovaries, representing primary ovarian MMs; only one similar case has been previously reported. In the other cases, widespread peritoneal tumor precluded definite conclusions about the primary or secondary nature of the ovarian involvement. That at least some of the latter were also primary ovarian MMs is suggested by a degree of ovarian enlargement, the striking parenchymal replacement, or both, which are not usually seen in cases of secondary ovarian involvement by peritoneal MMs. The clinical presentation was usually that of abdominal or pelvic pain or abdominal swelling, an adnexal mass on pelvic examination or at laparotomy, or combinations thereof. One tumor was an autopsy finding. There was no history of asbestos exposure in any patient. Eight patients underwent bilateral oophorectomy, usually with hysterectomy and biopsies of extraovarian tumor. Four patients were given chemotherapy and one, radiation therapy. Follow-up in five cases revealed that three patients had died of tumor at postoperative intervals of 8 to 44 months, one was alive with persistent tumor at 18 months, and one was alive with no clinical evidence of tumor at 11 years. The ovaries were replaced by tumors 3 to 15 cm in maximum diameter; seven were bilateral. The neoplastic tissue was typically solid, but small cysts were present in two cases, and one tumor was a unilocular cyst with a solid mural nodule. On microscopic examination, tumor involved both the serosa and the parenchyma of the ovary in seven cases, the serosa only in one case, and the parenchyma only in one case. Seven tumors were exclusively epithelial, with papillary, tubular-glandular, and solid patterns, and two were biphasic. The cells in the epithelial mesotheliomas usually exhibited moderate atypicality and a low mitotic rate. The stroma was typically hyalinized, and in three of the cases with a papillary pattern papillae with hyalinized cores were a striking finding. Psammoma bodies were present in three cases. Histochemical and immunohistochemical stains confirmed the mesothelial nature of the tumor cells. Because of the wide variety of microscopic patterns in MMs, the differential diagnosis of ovarian MM includes a variety of primary and metastatic ovarian tumors as well as other peritoneal mesothelial lesions.

Spectrum of peritoneal mesothelioma in childhood: clinical and histopathologic features, including DNA cytometry

Different types of peritoneal mesothelioma (PM) occur in children and adults. All these share certain histopathologic features but differ in other aspects, such as age of occurrence, site and sex predominance, etiology, and biologic behavior. The article describes four patients, two with cystic PM (one of whom had multiple recurrences) and two with malignant PM (one of whom had pleural metastases). These cases illustrate the variable behavior of this tumor in childhood and highlight the difficulties encountered in diagnosis and treatment. Three different groups of mesothelioma are recognized: a classic, asbestos-related, malignant mesothelioma of adults, typically occurring in the pleural cavity; a multicystic mesothelioma, predominantly affecting the pelvic peritoneum of young women and associated with a good prognosis; and mesotheliomas in children, which are not associated with asbestos exposure and have an unpredictable biologic behavior requiring individual treatment strategies. In the patients studied, DNA index measured by flow cytometry showed a difference between the cystic (aneuploid) and malignant (diploid) tumors. The proliferative rate (S phase) of the tumor was low in all four cases.

Malignant peritoneal mesothelioma in a 17-year-old boy with evidence of previous exposure to chrysotile and tremolite asbestos

We describe a case of malignant peritoneal mesothelioma arising in a 17-year-old boy. The diagnosis was based on a comprehensive study including light microscopy, histochemistry, immunohistochemistry, evaluation of the clinical course, and autopsy examination. Analytical transmission electron microscopy showed a concentration of 510,000 asbestos fibers/g dry lung tissue. The fibers were represented by chrysotile (62%) and tremolite (38%) asbestos. About 40% of the total fibers were longer than 5 microns. The presence of tremolite fibers was probably due to environmental exposure to contaminated cosmetic talc. This is the first reported case of pathologically proven exposure to asbestos dust in malignant mesothelioma of childhood and adolescence.

Mesothelial and related neoplasms in children and adolescents: a clinicopathologic and immunohistochemical analysis of eight cases

Mesothelioma is a neoplasm that occurs infrequently in childhood; only an estimated 2-5% of all cases present in the first two decades of life. The diagnosis may be perplexing because of its rarity and its pathologic similarities to other papillary or spindle cell neoplasms in the pediatric age group. We have studied eight cases of mesothelial or submesothelial-derived neoplasms of pleural (four cases) and peritoneal (four cases) origin in patients 4 to 17 years of age at diagnosis. Microscopically, six were epithelial, with papillary, tubuloglandular, and solid patterns. Two tumors were predominantly fibrous appearing, one a localized pleural fibroma and the other a diffuse pleural sarcomatoid mesothelioma. All of the tumors were immunoreactive for vimentin, and all except the pleural fibroma stained for either cytokeratin, epithelial membrane antigen, or both. None reacted with antibodies to carcinoembryonic antigen, placental alkaline phosphatase, or Leu-M1. At last follow-up, three patients were dead of tumor, three were alive and well, and two had been recently diagnosed and were undergoing treatment. These results indicate that the immunohistochemical profile delineated for mesothelioma in adults is equally applicable to mesothelial neoplasms in younger patients and is useful in establishing a diagnosis. The prognosis for malignant mesothelioma in childhood appears to be as unfavorable as the adult counterpart, with the possible exceptions of certain clinicopathologic subtypes.