The use of alkaline phosphatase and runx2 to distinguish osteosarcoma from other common malignant primary bone tumors in dogs

Abstract

In dogs, primary bone tumors can be difficult to distinguish with histopathology. Of those tumors, osteosarcoma (OSA) is the most common and aggressive. In this study, 4 immunohistochemistry markers—alkaline phosphatase (ALP), osteonectin (ON), osteopontin (OP), and runx2—were evaluated for their ability to distinguish OSA from other primary bone tumors. The 42 formalin-fixed, paraffin-embedded, primary canine bone tumors included 15 OSAs, 8 chondrosarcomas, 11 fibrosarcomas, and 8 histiocytic sarcomas. All 4 antibodies were highly sensitive for detection of osteosarcoma. ALP was the most sensitive at 100% and runx2 the most specific at 78%. Running ALP and runx2 in series resulted in a sensitivity of 87% and a specificity of 85%. This combination of immunomarkers resulted in a diagnostic panel for distinguishing osteosarcoma from other primary bone tumors.

Telangiectatic osteosarcoma in four dogs: Cytologic, histopathologic, cytochemical, and immunohistochemical findings

“…BCIP/ NBT cannot be performed on formalin-fixed tissues due to the epimembranous location of the ALP enzyme and current immunohistochemical options for confirmation of bone origin perform poorly, conferring an advantage to cytologic evaluation of lytic bone lesions for OSA. 6 In our cases, cytologic findings included an atypical population of pleomorphic mesenchymal cells with variably distinct to irregular cytoplasmic borders, scant to abundant cytoplasm ranging from pale to deeply basophilic. Nuclei were pleomorphic and typically measured 2-4× the diameter of an erythrocyte with a variable nuclear to cytoplasmic ratio and frequent karyomegaly.…”

“…1,[3][4][5] In a recent study of primary bone tumors in dogs, immunohistochemical staining of formalin-fixed tissues for ALP and runx2 in series was 87% sensitive and 85% specific for osteosarcoma. 6 Telangiectatic osteosarcoma (tOSA) is an uncommon subtype of OSA in dogs. Clinically, tOSA can be difficult to distinguish from HSA of bone, as both are characterized by monostotic aggressive lesions radiographically and by large blood-filled spaces within bone histologically.…”

“…In canine tumors without obvious osteoid formation, it may be difficult to distinguish OSA from other primary bone sarcomas 1,3–5 . In a recent study of primary bone tumors in dogs, immunohistochemical staining of formalin‐fixed tissues for ALP and runx2 in series was 87% sensitive and 85% specific for osteosarcoma 6 …”

“…Distinguishing OSA from other sarcomas of bone is further enhanced using BCIP/NBT cytochemical staining of cytology smears for ALP activity, 4,11,12 although care must be taken to confirm staining in atypical cells as benign cells are also positive. BCIP/NBT cannot be performed on formalin‐fixed tissues due to the epimembranous location of the ALP enzyme and current immunohistochemical options for confirmation of bone origin perform poorly, conferring an advantage to cytologic evaluation of lytic bone lesions for OSA 6 …”

Canine soft tissue sarcomas: the expression of RUNX2 and karyopherin alpha-2 in extraskeletal (soft tissues) and skeletal osteosarcomas

“…The antibodies selected for the comparative study were RUNX2 (Santa Cruz, clone F-2) ( 13 ), and karyopherin alpha-2 ( 7 ) (Santa Cruz, clone B-9).…”