title: Immunoglobulin crystal-storing histiocytosis in a pleural effusion from a woman with IgA kapa multiple myeloma: a case report.
abstract: BACKGROUND
  Crystal-storing histiocytosis (CSH) is a rare disorder occurring in patients with lymphoproliferative diseases, predominantly multiple myeloma and low grade B-cell lymphoma. This report presents the first case of CSH diagnosed on pleural fluid from a patient with multiple myeloma (MM).
  
  
  METHODS
  A 79-year-old women with IgA kappa MM underwent thoracocenthesis and thoracic drainage because of a pleural effusion. Cytologic and immunocytochemical examination of pleural fluid revealed abundant histiocytic, CD68-positive cells with prominent intracytoplasmic, needlelike, crystalloid inclusions showing strong immunopositivity for IgA heavy and kappa light chains. Identical crystals were observed on an extracellular background. No myeloma infiltration was detected. Two weeks later, examination of new pleural fluid from the patient showed a similar cytologic picture, but, in addition, isolated plasma cell features were identified. They were too few for a meaningful determination of clonality. The patient died I month after the CSH diagnosis.
  
  
  CONCLUSIONS
  This case illustrates the value of cytologic examination of serous fluids from patients with plasma cell dyscrasias, not only to evaluate possible infectious or neoplastic causes but also to diagnose CSH.
authors.affiliation: Section of Cytology, Service of Anatomic Pathology, Hospital Juan Canalejo, La Coruña, Spain. ignacio_galed@canalejo.org
authors.forename: Ignacio
authors.initials: I
authors.lastname: Galed-Placed
mesh_terms: D000368:Aged; D015703:Antigens, CD / Q000276:immunology; D015214:Antigens, Differentiation, Myelomonocytic / Q000276:immunology; D001707:Biopsy, Needle; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology; D017809:Fatal Outcome; D005260:Female; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology; D006644:Histiocytes / Q000276:immunology / Q000473:pathology*; D015614:Histiocytosis / Q000175:diagnosis* / Q000276:immunology* / Q000503:physiopathology; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology*; D050440:Immunoglobulin Subunits / Q000737:chemistry / Q000276:immunology; D002479:Inclusion Bodies / Q000276:immunology / Q000473:pathology; D009101:Multiple Myeloma / Q000150:complications*; D035422:Pleural Cavity / Q000276:immunology / Q000473:pathology; D010996:Pleural Effusion / Q000175:diagnosis* / Q000276:immunology* / Q000503:physiopathology; D012272:Ribs / Q000473:pathology; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D007070:Immunoglobulin A; D050440:Immunoglobulin Subunits; C067980:CD68 antigen, human; D000097382:CD68 Molecule