Lymphohistiocytoid mesothelioma of the pleura

Abstract

Lymphohistiocytoid mesothelioma (LHM), reported to be a rare variant of sarcomatoid mesothelioma, is challenging to differentiate from non-Hodgkin's lymphoma due to marked lymphocytic infiltration. To aid accurate recognition of LHM, we examined immunohistochemical, in situ hybridization (ISH) of Epstein-Barr virus RNA (EBER-1) mRNA, fluorescence ISH (FISH) for homozygous deletion of 9p21, and asbestos analysis in four cases (three men and 1 woman). Three patients died, while Case 4 was still alive 19 months after extrapleural pneumonectomy. Histologically, these cases were characterized by heavy lymphocytic infiltration. All neoplastic cells were positive for calretinin, AE1/AE3, and epithelial membrane antigen, but negative for CEA. EBER1 factor was negative. FISH analysis demonstrated homozygous deletion of the 9p21 locus in three of the four cases. In Case 1: (i) autopsy findings showed mesothelioma primarily located in the right parietal pleura, but metastasized into the left lung and abdominal organs; (ii) the histological findings at autopsy indicated sarcomatoid mesothelioma; and (iii) we found asbestos bodies and fibers in extracts from lung tissue (Cases 1 & 4) using digestion with bleaching fluid. LHM, an infrequent variant of sarcomatoid mesothelioma, displayed homozygous deletion of the 9p21 locus (three of four cases), and has a relatively favorable prognosis for the sarcomatoid type.

Peritoneal malignant mesothelioma (PMM), and primary peritoneal serous carcinoma (PPSC) and reactive mesothelial hyperplasia (RMH) of the peritoneum. Immunohistochemical and fluorescence in situ hybridisation (FISH) analyses

“…All antibodies were incubated overnight at 4°C. The monoclonal and polyclonal antibodies used are listed in table 2, together with the antigen-retrieval conditions 21 22…”

“…Tissue sections on slides were deparaffinised and hydrated to distilled water, and examination was performed in the same way as in our previous study 21. Only individual and well delineated cells were scored.…”

Guidelines for Pathologic Diagnosis of Malignant Mesothelioma: 2012 Update of the Consensus Statement from the International Mesothelioma Interest Group

“…Sarcomatoid MMs usually consist of spindle cells but can be composed of lymphohistiocytoid cells and/or may also contain heterologous rhabdomyosarcomatous, osteosarcomatous, or chondrosarcomatous elements. 24,25 Mixed or biphasic MMs contain both epithelioid and sarcomatoid areas within the same tumor. [26][27][28][29][30][31][32] In general, the differential diagnosis for MM depends on its basic histologic category: the differential diagnosis for epithelioid MM includes carcinomas and epithelioid cancers; the differential diagnosis for sarcomatoid MM includes sarcomas and other spindle cell neoplasms; and the differential diagnosis of mixed MM includes mixed or biphasic tumors such as synovial sarcoma and metastatic pleomorphic carcinoma of lung.…”

Small intestinal intussusception in an adult

“…Galateau-Sallé et al 3 suggested that the survival  in  patients with LHM is more like that of the epithelioid or biphasic subtype of MPM. On the other hand, Kawai et al 4 reported a patient diagnosed with LHM whose autopsy indicated sarcomatous mesothelioma.…”