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Enostosis -like lesions. Katie Phillips. Hanz accession 147214. 12 yr old warmblood gelding Used for dressage 2 week history of lameness Presented for evaluation of a sore back. 3/5 Lame RF & LH. No change with flexion Could not be blocked . Hanz RF.
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Enostosis-like lesions Katie Phillips
Hanzaccession 147214 • 12 yr old warmblood gelding • Used for dressage • 2 week history of lameness • Presented for evaluation of a sore back. • 3/5 Lame RF & LH. • No change with flexion • Could not be blocked
Hanz RF Differentials: enostosis-like lesion, or less likely fracture, osteomyelitis, bone infarct, osteonecrosis. VRUS 2009
Enostosis • Scintigraphically as focal or multifocal areas of intense increased radioisotope uptake within the medullary cavity of long bones. • Radiographically as one or multiple round to irregular shaped opacities within the medullary cavity. • A mass of proliferating bone within a bone. –Stedman • A morbid bony growth developed within the cavity of a bone or on the internal surface of the bone cortex. -Dorland
Hanz radiographs Well circumscribed intramedullary sclerosis with no apparent involvement of the cortex.
Enostosis-like lesions in the literature • Case reports and clusters of case reports, only. • All describe similar scintigraphy and radiographic findings. • Etiology is unknown • Often considered incidental • If no other cause of lameness is identified they are considered the cause. • O’Neil 2011 – report 15/21 cases where enostosis-like lesions were considered the cause of lameness.
Features • Multiple breeds and disciplines described. • May be single or multiple lesions, often multiple limbs. • Frequently associated with dorsal endocortexdirectly across from nutrient foramen. • Lameness and lesions resolve with time.
Speculation Similarities to Canine Panosteitis • Radiopharmacutical uptake & medullary sclerosis • Nidus in vicinity of nutrient foramen • Radiographic changes don’t always correlate with lameness. • Similar temporal changes • Histologically the same • But… case reports are all horses in work (skeletally mature). Human enostosis • AKA bone islands • Typically not scintigraphically active • Asymptomatic, static, solitary • Usually metaphyseal or epiphyseal • Bone Infarct • Case report in horse- showed colic like pain, then lameness. • Time line is different for scintigraphy changes and radiographic lag.
IMAGING DIAGNOSIS—ENOSTOSIS-LIKE LESION IN THE FEMUROF A HORSESUSANNE M. STIEGER-VANEGAS, HEGE KIPPENES-SKOGMO, EBBA NILSSONVeterinary Radiology & Ultrasound, Vol. 50, No.5, 2009, pp 509–512. • Case report 15yr WB • Only case in literature with histology!! • 4/5 lame LH localization was not possible. • Histo: No inflammatory cells, no thrombus, no evidence of bone necrosis. Similar to panosteitis of young dogs. • No histological involvement of endosteum.
References • Stieger-Vanegas, Kippenes-Skogmo, Nilsson. Imaging diagnosis- Enostosis-like lesion in the femur of a horse. 2009.VRUS.50(5) 509-512 • Bassage, Ross. Enostosis-like lesions in the long bones of 10 horses:scintigraphic and radiographic features. 1998.Equine vet j. 30(1) 35-42 • Ramzan.Equine enostosis-like lesions:12 cases 2002 EVE14(3) 143-148. • Jones & McDiarmid. Case report:Multiple enostosis-like lesions in a racing thoroughbred. 2005.eve. 17(2 92-95 • O’Neil & Bladon.Retrospective study of scintigraphic and radiological findings in 21 cases of enostosis-like lesions in horses. 2011 veterinary record. 168:326
MRI – Travis 147695 There are regions of intense medullary T2-hyperintensity in the third metatarsal bone at the level of the nutrient artery. This appearance is consistent with enostosis but hematogenous osteomyelitis could also have this appearance.
Hanz – follow up • One dose IV Tildren • 2 months rest • Re-check: grade 1/5 lame RF, mildly positive to flexion LH.