title: Cytologic patterns of lymphadenopathy in dogs infected with Leishmania infantum.
abstract: BACKGROUND
  Lymphadenopathy in canine leishmaniosis has been reported as reactive lymphoid hyperplasia or granulomatous (histiocytic) lymphadenitis. However, we are unaware of information on the effect of latent Leishmania infection on lymph node cytology compared with clinically affected dogs.
  
  
  OBJECTIVE
  The aim of the present study was to investigate cytologic patterns of lymphadenopathy in dogs with clinical and subclinical forms of leishmaniosis and to correlate cytologic findings with the density of Leishmania amastigotes in fine needle aspiration (FNA) smears.
  
  
  METHODS
  FNA cytology of prescapular or popliteal lymph nodes was evaluated on 32 dogs with clinical evidence of leishmaniosis (group A), 24 subclinically infected dogs (group B), and 17 clinically healthy noninfected dogs (group C); groups were based on the results of serologic and PCR tests for Leishmania sp. Differential nucleated cell counts (based on 300 cells) and amastigote density were determined microscopically. Cytologic findings were categorized and compared among groups.
  
  
  RESULTS
  Cytologic abnormalities were found in 19 of 32 (59.4%) dogs in group A, 1 of 24 (4.2%) dogs in group B, and 2 of 17 (11.8%) dogs in group C and were significantly more frequent in group A than group B (P <.001) or C (P = .001). In group A, 68.7% of the dogs had lymphoid hyperplasia, 12.5% had lymphoid hyperplasia and histiocytic lymphadenitis, 6.3% had histiocytic lymphadenitis, and 3.1% had lymphoid hyperplasia and neutrophilic lymphadenitis. Lymphoid hyperplasia was also noted in 1 dog in group B, and lymphoid hyperplasia and eosinophilic lymphadenitis were each found in 1 dog in group C. Lymph node smears from 31 (96.9%) dogs in group A and 6 (25%) dogs in group B were positive for Leishmania amastigotes; however, no correlation was found between the density of amastigotes and cytopathologic patterns of lymphadenopathy.
  
  
  CONCLUSIONS
  Abnormal lymph node cytology is much more common in dogs with clinical leishmaniosis than in dogs with subclinical infection, and primarily involves lymphoid hyperplasia. Despite finding no association between the density of amastigotes and type of lymphadenopathy, lymph node cytology still is a valuable diagnostic tool for diagnosing canine leishmaniosis.
authors.affiliation: Clinic of Companion Animal Medicine, School of Veterinary Medicine, Aristotle University of Thessaloniki, Greece.
authors.forename: Mathios E
authors.initials: ME
authors.lastname: Mylonakis
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Papaioannou
authors.forename: Manolis N
authors.initials: MN
authors.lastname: Saridomichelakis
authors.forename: Alexander F
authors.initials: AF
authors.lastname: Koutinas
authors.forename: Charalambos
authors.initials: C
authors.lastname: Billinis
authors.forename: Vassilios I
authors.initials: VI
authors.lastname: Kontos
mesh_terms: D000375:Aging; D000818:Animals; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D006965:Hyperplasia / Q000473:pathology / Q000662:veterinary; D018314:Leishmania infantum / Q000302:isolation & purification; D007898:Leishmaniasis, Visceral / Q000473:pathology / Q000662:veterinary*; D008206:Lymphatic Diseases / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D008297:Male