title: Membranous lamellar cytoplasmic inclusions in histiocytes and mesothelial cells of serous fluids. Their relationship to phagocytosis of red blood cells.
abstract: OBJECTIVE
  To define the composition of cytoplasmic inclusions forming stacks and concentric whorls in histiocytes and mesothelial cells of serous fluids, imparting to them a resemblance to Gaucher cells, and to draw conclusions on the mechanism of their formation.
  
  
  METHODS
  Three serous fluids (one pleural and two pericardial) containing a fair number of the cells referred to were progressively subjected to the following studies: (1) cytochemistry for mucopolysaccharides, proteins, phospholipids and hemoglobin; (2) immunocytochemistry for immunoglobulins IgA, IgG, IgM and lysozyme; (3) transmission electron microscopy (TEM), and (4) scanning electron microscopy-based energy dispersive X-ray microanalysis (SEM-EDAX).
  
  
  RESULTS
  All three specimens were blood stained and contained large numbers of histiocytes and mesothelial cells, arranged singly and in groups, with abundant cytoplasmic inclusions. The inclusions stained strongly positive for phospholipids, weakly positive for hemoglobin and negative for all other substances examined by cytochemistry and immunocytochemistry. By TEM the inclusions had a concentric lamellar membranous structure, reminiscent of myelinosomes or lamellar bodies of lipid-forming or -storing cells. There was also phagocytosis by histiocytes and mesothelial cells of red blood cells, which were mostly in a degenerated state. SEM-EDAX of inclusion-bearing cells showed a modest peak for phosphorus and a variable but small peak for iron, which corroborated the cytochemical and TEM findings.
  
  
  CONCLUSIONS
  Since there was not metabolic or other systemic disease in the patients to account for these cells, we posit that phospholipids derived from cell membranes of phagocytized cells, especially red blood cells, provide the building blocks for the formation of such inclusions as they enter the metabolic pathway of phagocytic cells (mesothelial cells and histiocytes) and appear in their lysosomal structures. It is advantageous for cytologists to be familiar with significance of such changes and not to mistake them for metabolic or other systemic disease.
authors.affiliation: Department of Pathology, University of Texas Medical Branch, Galveston 77550, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zaharopoulos
authors.forename: J W
authors.initials: JW
authors.lastname: Wen
authors.forename: J
authors.initials: J
authors.lastname: Wong
mesh_terms: D000328:Adult; D000368:Aged; D001826:Body Fluids / Q000737:chemistry / Q000166:cytology*; D002318:Cardiovascular Diseases / Q000473:pathology; D004577:Electron Probe Microanalysis; D004848:Epithelium / Q000648:ultrastructure*; D004910:Erythrocyte Membrane; D004912:Erythrocytes / Q000166:cytology*; D006025:Glycosaminoglycans / Q000032:analysis; D006454:Hemoglobins / Q000032:analysis; D006470:Hemorrhage / Q000473:pathology; D006644:Histiocytes / Q000648:ultrastructure*; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D002479:Inclusion Bodies / Q000648:ultrastructure*; D007425:Intracellular Membranes / Q000648:ultrastructure*; D007676:Kidney Failure, Chronic / Q000473:pathology; D008297:Male; D008563:Membrane Lipids / Q000032:analysis*; D008565:Membrane Proteins / Q000032:analysis*; D008854:Microscopy, Electron; D008875:Middle Aged; D009113:Muramidase / Q000032:analysis; D010490:Pericardial Effusion / Q000737:chemistry / Q000166:cytology; D010493:Pericarditis / Q000473:pathology; D010587:Phagocytosis; D010743:Phospholipids / Q000032:analysis; D010996:Pleural Effusion / Q000737:chemistry / Q000166:cytology
chemical_list: D006025:Glycosaminoglycans; D006454:Hemoglobins; D007136:Immunoglobulins; D008563:Membrane Lipids; D008565:Membrane Proteins; D010743:Phospholipids; D009113:Muramidase