Form Of Mesothelioma Research Articles

New developments in mesothelial pathology.

This review article examines some new and some problem areas in mesothelial pathology, four of which are discussed, as follows. (1) The concept of mesothelioma in situ: this lesion is defined as a single layer of bland mesothelial cells without evidence of invasion, but that have lost BAP1 and/or MTAP by immunohistochemistry. Benign reactions can exactly mimic mesothelioma in situ, but a hint to the correct diagnosis is a story of recurrent pleural effusions/ascites of unknown aetiology without radiological or direct visual evidence of tumour. (2) The nature of well-differentiated papillary mesothelial tumour (WDPMT): WDPMT has a long history of arguments regarding its behaviour, and this uncertainty can now be seen to arise, in part, from the observation that some forms of mesothelioma in situ microscopically look exactly like WDPMT. Hence, it is recommended to always run at least a BAP1 stain on any lesion that looks like WDPMT. Both flat and WDPMT-like mesothelioma in situ are strongly associated with eventual development of invasive mesothelioma, but this process is relatively slow. (3) New immunostains for separating mesothelioma from other tumours: here, it is proposed that in most cases, and particularly when the differential is epithelioid mesothelioma versus non-small cell lung cancer, one can make this separation with extremely high sensitivity and specificity using just two stains: HEG1 and claudin-4. (4) Markers for separating benign from malignant mesothelial proliferations: this topic is briefly reviewed, with an indication of which markers are generally accepted and the best utilisation and possible limitations of each marker.

Mesothelioma In Situ Mimicking Well-differentiated Papillary Mesothelial Tumor.

We have previously hypothesized that well-differentiated papillary mesothelial tumor (WDPMT) consists of 2 morphologically identical lesions, one of which is true WDPMT, while the other is a form of mesothelioma in situ. Here, we report 8 examples of the latter phenomenon, 3 with pleural disease (2 men/1 woman, ages 66 to 78y); and 5 with peritoneal disease (all women, ages 31 to 81y). At presentation the pleural cases all had effusions but no evidence of pleural tumor on imaging. Four of the 5 peritoneal cases had ascites as the initial finding and all 4 had nodular lesions that by imaging and/or direct inspection were thought to represent a diffuse peritoneal malignancy. The fifth peritoneal case presented with an umbilical mass. Microscopically, the pleural and peritoneal lesions looked like diffuse WDPMT, but all had lost BAP1. Occasional microscopic foci of superficial invasion were present in 3/3 pleural cases, while single nodules of invasive mesothelioma and/or occasional foci of superficial microscopic invasion were found in all of the peritoneal cases. The pleural tumor patients developed what clinically appeared to be invasive mesothelioma at 45, 69, and 94 months. Four/five peritoneal tumor patients underwent cytoreductive surgery and heated intraperitoneal chemotherapy. Three with follow-up data are alive without recurrence at 6, 24, and 36 months; 1 patient refused treatment but is alive at 24 months. We conclude that mesothelioma in situ morphologically mimicking WDPMT is strongly associated with the synchronous or metachronous development of invasive mesothelioma, but that these lesions appear to progress very slowly.

Diffuse Malignant Peritoneal Mesothelioma Presenting as Intestinal Obstruction

Diffuse malignant peritoneal mesothelioma (DMPM) represents 90% of all peritoneal forms of mesothelioma. It affects mainly patients 50-69 years old. In 50% of cases there is a history of asbestos exposure. The clinical presentation of the disease is not characteristic: nonspecific abdominal pain, weight loss, and abdominal distension are common. Ascites occurs in 90% of the patients. Bowel obstruction is a late manifestation. We present three patients with DMPM, without a history of asbestos exposure and without ascites, who presented with complete bowel obstruction. All patients underwent emergency operations, and palliative surgical procedures were performed. Each patient died within 3 to 6 months postoperatively.

Solitary fibrous tumor of the larynx: a case report and review of the literature.

Abstract Solitary fibrous tumors are relatively rare mesenchymal neoplasms that were originally described as pleural- or peritoneal-based lesions. Although they were considered a form of mesothelioma, subsequent investigation failed to reveal mesothelial differentiation. Characterization of their histologic and immunohistochemical features, as well as identification in a multitude of nonmesothelial-based locations has further served to distinguish these lesions from the more diffuse and aggressive mesothelioma. Reports of solitary fibrous tumor in the larynx are extremely rare. We report a case of solitary fibrous tumor of the larynx in a 38-year-old man.

Solitary Fibrous Tumor of the Larynx: A Case Report and Review of the Literature

Solitary fibrous tumors are relatively rare mesenchymal neoplasms that were originally described as pleural- or peritoneal-based lesions. Although they were considered a form of mesothelioma, subsequent investigation failed to reveal mesothelial differentiation. Characterization of their histologic and immunohistochemical features, as well as identification in a multitude of nonmesothelial-based locations has further served to distinguish these lesions from the more diffuse and aggressive mesothelioma. Reports of solitary fibrous tumor in the larynx are extremely rare. We report a case of solitary fibrous tumor of the larynx in a 38-year-old man.