title: Canine angiosarcoma: cytologic, histologic, and immunohistochemical correlations.
abstract: BACKGROUND
  Angiosarcomas (AS) are malignant tumors that arise from vascular endothelial cells and are common in dogs. Histologically, AS are markedly heterogeneous neoplasms that make interpretation by cytology difficult.
  
  
  OBJECTIVE
  Our objective was to evaluate the cytologic features of canine AS and look for additional diagnostic criteria.
  
  
  METHODS
  Cytologic specimens from 19 histologically and immunohistochemically confirmed cases of canine AS were extensively reviewed for cytologic features. We compared cytologic, histopathologic, and immunohistochemical findings.
  
  
  RESULTS
  Neoplastic cells in 14 cytology specimens had a high-grade sarcomatous appearance, whereas in 4 specimens the cells were extremely pleomorphic, ranging from sarcomatous to epithelioid. In the remaining case, the neoplastic cells were low grade, spindle shaped, and monomorphic. Other relevant cytologic findings were blood contamination (18/19 cases), cellular cohesiveness (16/19), punctate cytoplasmic vacuolation (19/19), background neutrophilia (11/19) and eosinophilia (5/19), erythrophagocytosis (8/19), extramedullary hematopoiesis (8/19), and apoptotic leukocytes (14/19). Vasoformative features (ie, pseudoacinar structures) were observed in 7 of 19 samples. Histologically, 16 neoplasms had a proliferative pattern typical of well-differentiated canine AS. Three tumors were atypical poorly differentiated AS; 2 of these had a striking epithelioid pattern and 1 was a poorly differentiated spindle cell tumor with focal vascular differentiation. Immunohistochemically, tumor cells in 16 cases were positive for both endothelial markers tested (Factor VIII-related antigen [FVIII-ra] and CD31 antigen), 2 were positive for CD31 only, and 1 was positive for FVIII-ra only. The epithelioid AS were negative for cytokeratins.
  
  
  CONCLUSIONS
  The cytologic characteristics of canine AS are widely heterogeneous, but supplementary findings can provide clues that are useful for making a cytologic diagnosis. Histologic and immunohistochemical confirmation is nonetheless warranted in all cases.
authors.affiliation: Pronto Soccorso Veterinario, Lodi, Italy. bertwalter@libero.it
authors.forename: Walter
authors.initials: W
authors.lastname: Bertazzolo
authors.forename: Marta
authors.initials: M
authors.lastname: Dell'Orco
authors.forename: Ugo
authors.initials: U
authors.lastname: Bonfanti
authors.forename: Gabriele
authors.initials: G
authors.lastname: Ghisleni
authors.forename: Mario
authors.initials: M
authors.lastname: Caniatti
authors.forename: Carlo
authors.initials: C
authors.lastname: Masserdotti
authors.forename: Elisa
authors.initials: E
authors.lastname: Antoniazzi
authors.forename: Luca
authors.initials: L
authors.lastname: Crippa
authors.forename: Paola
authors.initials: P
authors.lastname: Roccabianca
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000378:metabolism / Q000473:pathology*; D004285:Dogs; D006394:Hemangiosarcoma / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary