title: Diagnostic cellular yield is superior with full pars plana vitrectomy compared with core vitreous biopsy.
abstract: OBJECTIVE
  Vitreous biopsy for the cytological assessment of suspected intraocular lymphoma and vitritis of uncertain aetiology is a standard investigation. The types of specimens generated and the diagnostic rate are variable within and between centres. There are many reasons for this but one observation that has not been considered previously is the differential distribution of cells in the vitreous gel. To test this possibility, five consecutive patients with suspected vitreous involvement by lymphoma or vitritis of uncertain aetiology underwent a core vitreous biopsy immediately before a planned full pars plana vitrectomy (PPV) and the cellularity of the two sampling techniques compared.
  
  
  METHODS
  A prospective study of five consecutive patients requiring vitreous sampling to secure a firm diagnosis. For each of five patients, the core vitreous biopsy specimen was received in a universal tube and the PPV specimen was received in a vitreous cassette. Fluid (0.25 ml) was removed from both specimens, centrifuged and haematoxylin and eosin (H&E) stained slides prepared per sampling method. The slides were examined with a light microscope, the most cellular field selected and the number of cells per mm(2) counted and compared between sampling techniques.
  
  
  RESULTS
  PPV specimen's, revealed a cellularity range that was 7.4 to 78 × (average 31 ×) greater than a core vitreous biopsy. In the two cases of a final diagnosis of intraocular lymphoma, the vitreous core biopsy was non-diagnostic. Furthermore, the PPV specimen generated additional cellular material for numerous ancillary investigations to permit a secure diagnosis.
  
  
  CONCLUSIONS
  The results of this differential vitreous sampling study has strengthened our anecdotal slit lamp clinical observations that inflammatory cells and lymphoma cells are concentrated more in the cortical vitreous. Therefore, vitreous cells have less chance to be sampled if a single core vitreous biopsy is performed. Indeed, the two cases of confirmed lymphoma generated a non-diagnostic core vitreous biopsy. In our centre, this study has lead to PPV being performed as a gold standard on all patients with suspected intraocular lymphoma or vitritis of uncertain aetiology.
authors.affiliation: National Specialist Ophthalmic Pathology Service (NSOPS), Department of Histopathology, Royal Hallamshire Hospital, Sheffield, UK. hardeep.mudhar@sth.nhs.uk
authors.forename: H S
authors.initials: HS
authors.lastname: Mudhar
authors.forename: R
authors.initials: R
authors.lastname: Sheard
mesh_terms: D000293:Adolescent; D000368:Aged; D001706:Biopsy / Q000379:methods; D002452:Cell Count; D003937:Diagnosis, Differential; D005128:Eye Diseases / Q000473:pathology*; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000473:pathology*; D008297:Male; D011446:Prospective Studies; D014821:Vitrectomy; D014822:Vitreous Body / Q000166:cytology / Q000473:pathology*