Localized malignant pleural mesothelioma showing a thoracic mass and metastasizing to the stomach

Localized pleural mesothelioma in a dog

Malignant mesotheliomas with localized growth are extremely rare in dogs. A 9-year-old male dog presented with a localized tumour that originated from the parietal pleura and had polypoid growth in the thoracic cavity. Histological examination revealed that the tumour consisted of tubular formations with scattered cysts and minimal papillary growth pattern. Neoplastic cells were immunopositive for mesothelial markers (calretinin and Wilms' tumour gene 1) and negative for carcinoma markers (thyroid transcription factor 1 and tumour protein 63). The animal was alive with no recurrence or metastasis/dissemination 11 months after surgery. To the best of our knowledge, this is the first report of a localized mesothelioma in a dog without metastasis/dissemination and highlights the value of mesothelial markers for an accurate diagnosis.

Three cases of synovial sarcoma of gastric wall: A case report and review of the literature

Synovial sarcoma (SS) is a malignant soft tissue neoplasm that occurs in various parts of the human body, but most commonly affects the extremities. Its diagnosis of synovial sarcoma often requires adjunctive techniques such as immunohistochemical staining and molecular studies, especially for synovial sarcoma at unusual locations. SS at a gastrointestinal location is exceedingly rare. We report here three cases of primary gastric synovial sarcoma. Malignant gastric mesenchymal tumor has many differential diagnoses other than synovial sarcoma, such as gastrointestinal stromal tumor (GIST), leiomyosarcoma, schwannoma, malignant peripheral nerve sheath tumor (MPNST) and so on. In our three cases, using reverse transcription polymerase chain reaction (RT-PCR) and direct sequencing, we detected an SS18-SSX1 fusion gene, which is specific to synovial sarcoma. In addition, we found the reduced expression of SMARCB1/INI1 in the tumor cells in two of the three cases. Through histopathological, immunohistochemical, and molecular analyses, we confirmed the diagnosis of primary gastric synovial sarcoma.

A Case of Localized Malignant Peritoneal Mesothelioma Evaluated by 18F-FDG PET/CT

Localized malignant mesothelioma is rare. The prognosis is generally more favorable for this condition than for diffuse malignant mesothelioma. An elderly woman recently complained of abdominal pain, fever, and weight loss. She had no history of asbestos exposure. Her serum CEA level was elevated. Plain CT revealed a mass under the left diaphragm, with liquefaction and necrosis. A contrast-enhanced scan showed circular enhancement of the mass. A subsequent biopsy of the mass revealed a poorly differentiated carcinoma. PET/CT showed a significant FDG-avid subphrenic mass without any indications of metastasis. Postoperative pathological and immunohistochemical examination confirmed a case of malignant mesothelioma.

A challenging diagnosis of malignant mesothelioma with osteosarcomatous differentiation metastasizing to bone

Malignant pleural mesothelioma (MPM) is an insidious primary neoplasm of the pleura that can be challenging to diagnose and is commonly considered to be only locally invasive. We present the case of a 74-year-old male who presented with clinical features of MPM but from whom pleural fluid and biopsies initially suggested benign pathology. He later developed diffuse bony metastases and re-examination of pleural biopsies using modern immunohistochemistry and molecular testing revealed a diagnosis of sarcomatoid and desmoplastic MPM with heterologous osteosarcomatous differentiation. This case not only demonstrates the rare potential of skeletal metastasis of MPM, but also highlights the importance of recognizing the utility of modern diagnostic tests and their potential to prevent the need for unnecessary invasive procedures. To our knowledge this is the first description of this rare histological sub-type presenting with skeletal metastases.

Localized malignant mesothelioma, an unusual and poorly characterized neoplasm of serosal origin: best current evidence from the literature and the International Mesothelioma Panel

Localized malignant mesotheliomas (LMM) is an uncommon and poorly recognized neoplasm. Its pathologic diagnosis is often surprising in patients with serosal/subserosal based localized tumors that are clinically suspicious for metastatic lesions or primary sarcomas. Once a tumor is diagnosed as "mesothelioma", LMM is often mistaken for diffuse malignant mesothelioma (DMM). Best currently available evidence about LMM was collected from the literature and cases diagnosed by members of the International Mesothelioma Panel (IMP). One hundred and one (101) LMM have been reported in the English literature. Patients had localized tumors with identical histopathologic features to DMM. Patients ranged in age from 6 to 82 years; 75% were men. Most (82%) of the tumors were intrathoracic. Others presented as intrahepatic, mesenteric, gastric, pancreatic, umbilical, splenic, and abdominal wall lesions. Tumors varied in size from 0.6 to 15 cm. Most patients underwent surgical resection and/or chemotherapy or radiation therapy. Median survival in a subset of patients was 29 months. Seventy two additional LMM from IMP institutions ranged in age from 28 to 95 years; 58.3% were men. Sixty tumors (83.3%) were intrathoracic, others presented in intraabdominal sites. Tumors varied in size from 1.2 to 19 cm. Median survival for 51 cases was 134 months. Best evidence was used to formulate guidelines for the diagnosis of LMM. It is important to distinguish LMM from DMM as their treatment and prognosis is different. A multidisciplinary approach is needed for the diagnosis of LMM as it shows identical histopathology and immunophenotype to DMM.

Localized malignant pleural mesothelioma arising in the interlobar fissure: a unique surgical case masquerading clinicopathologically as primary lung adenocarcinoma

An 80-year-old male with previous workplace exposure to asbestos presented with a history of an increase in the pulmonary-to-hilar mass, measuring more than 50 mm in diameter, likely in the right lower lobe. We first interpreted it as suspicious of primary lung adenocarcinoma with direct invasion to the right hilar lymph node. A right middle and lower lobectomy with partial resection of upper lobe was performed, and gross examination showed a hilar tumor lesion, involving the middle/lower lobe to hilar lymph node and looking whitish to yellow-grayish, partly adjacent to the right pulmonary artery. On microscopic examination, the tumor was located on the extrapulmonary, interlobar pleural fissure, predominantly composed of a proliferation of atypical epithelioid cells, often arranged in an irregular and fused tubular growth pattern with an involvement of pulmonary artery. Immunohistochemically, these atypical cells are positive for several mesothelial markers, including calretinin, cytokeratin 5/6, and WT-1, whereas negative for thyroid transcription factor 1. Furthermore, p16 deletions were specifically detected by fluorescence in situ hybridization, and electron microscopy showed numerous, significantly elongated microvilli. Taken together, we finally made a diagnosis of localized malignant pleural mesothelioma, epithelioid-type, arising in the right interlobar fissure between lower and middle lobes. We should be aware that, owing to its characteristic features, clinicians and pathologists might be able to raise interlobar fissure localized malignant pleural mesothelioma as one of the differential diagnoses, based on careful clinicopathological examinations.

Localized malignant pleural mesothelioma with renal metastasis

Localized malignant pleural mesothelioma (LMM) is a rare subset of malignant pleural mesothelioma. Its epidemiology, biology, natural history and optimal treatment are poorly understood. We report a case of LMM treated aggressively with complete surgical resection and adjuvant radiotherapy, but subsequently complicated by local chest wall recurrence and solitary metastasis to the kidney. This case is examined in the context of a small number of cases of LMM in the literature to emphasize the existence of this rare disease entity, their unusual biological behaviour and the need for further tumour molecular and genomic research.

Malignant mesothelioma presenting as a giant chest, abdominal and pelvic wall mass

Malignant mesothelioma (MM) is a relatively rare carcinoma of the mesothelial cells, and it is usually located in the pleural or peritoneal cavity. Here we report on a unique case of MM that developed in the chest, abdominal and pelvic walls in a 77-year-old female patient. CT and MRI revealed mesothelioma that manifested as a giant mass in the right flank and bilateral pelvic walls. The diagnosis was confirmed by the pathology and immunohistochemistry. Though rare, accurate investigation of the radiological features of a body wall MM may help make an exact diagnosis.