At this week’s KCC, we had a great variety of cases. The first case was tricky to interpret; the radiographic findings did not fit well with the history and clinical signs. This should always raise your index of suspicion that there is something else going on. Here are the case summaries, no images this time.
8 year old FS Australian Shepherd with acute right forelimb lameness.
Radiographs of the right radius and ulna are presented. There is a thin-walled lucency in the distal lateral radius. There is no evidence of cortical disruption or periosteal reaction. The zone of transition is sharp. Differential diagnoses include a bone cyst, and neoplasia (osteosarcoma, round cell neoplasia). Considering the history, the dog is older which is less characteristic of a bone cyst. In addition, it does not explain the acute lameness. The metaphyseal location of the lesion could also fit with a primary bone tumor. Because of the thin cortex, a pathological fracture is possible and follow-up radiographs are be warranted. Possible next steps include thoracic radiographs and bone aspirate or biopsy. Diagnosis: fibrosarcoma.
6 year old male neutered German Shepherd with an abdominal mass.
On abdominal radiographs, there is a large soft tissue mass in the right abdomen or retroperitoneal space. It is causing a mass effect with peripheral displacement of the small intestine. The left kidney is visible and caudally displaced. The right kidney is not clearly visible, but appears to be displaced by the mass to the ventral abdomen on the lateral projection. The spleen is visible and appears normal. Differentials include right renal hydronephrosis, neoplasia, other organ neoplasia (mesenteric, splenic, pancreatic), abscess, hematoma, granuloma. An abdominal ultrasound or EU was recommended. An excretory urogram was performed with two available time points. The left kidney is normal with a normal nephrogram and pyelogram. The right kidney enhances poorly, and the mass apears to be continuous with the pelvis. The mass does not enhance, but there is an irregular rim of contrast enhancement at the right renal pelvis which appears to be dilated renal diverticuli. A segment of normal ureter travels toward the bladder. Revised differentials include a retroperitoneal mass causing right ureteral obstruction (cyst of renal or ureteral origin, neoplasia, infectious, inflammatory). Diagnosis: cystadenocarcinoma and nodular dermatofibrosis (skin lesions not mentioned in history). German Shepherds are predisposed to this condition, which is caused by a mutation in the canine BHD gene. Multifocal renal tumors, uterine lyomyomas, and skin nodules comprised of dense collagen are all part of the syndrome.
Moe, L. and B. Lium (1997). “Computed tomography of hereditary multifocal renal cystadenocarcinomas in German shepherd dogs.” Veterinary Radiology & Ultrasound 38(5): 335-43.
Lingaas, F., K. E. Comstock, E. F. Kirkness, A. Sorensen, T. Aarskaug, C. Hitte, M. L. Nickerson, L. Moe, L. S. Schmidt, R. Thomas, M. Breen, F. Galibert, B. Zbar and E. A. Ostrander (2003). “A mutation in the canine BHD gene is associated with hereditary multifocal renal cystadenocarcinoma and nodular dermatofibrosis in the German Shepherd dog.” Hum Mol Genet 12(23): 3043-53.
4 year old Quarter Horse colt who caught limb in fence. 4/5 lame RH.
At the pastern, there is synovial proliferation and effusion in the digital sheath with soft tissue thickening. The margin of the tendon sheath is disrupted distally with fluid collecting in the subcutaneous tissues. The origin of the medial collateral ligament has a central anechoic disruption seen in short and long axis. Diagnosis: tenosynovitis with ruptured tendon sheath, and desmitis of the medial collateral ligament. Recommendation is to perform ultrasound guided centesis. Notes: To tell the difference between the transverse and longitudinal views of the collateral ligament, look at the contour of P1. The transverse is concave and parallel to the image, while the longitudinal image has an angled bone surface.
4 year old domestic short hair cat with several days of fever, anorexia, sneezing and coughing.
On thoracic radiographs, there is a diffuse bronchointerstitial pattern. The lungs are mildly hyperinflated. There is increased opacity in the area of the esophagus on the lateral projection. Differentials for this non-specific radiographic pattern include infectious lower airway disease such as fungal (cryptococcus, toxoplasmosis, histoplasmosis, blastomycosis), heartworm, bacterial, parasitic or viral. Diagnosis: Aelurostrongylus abstrusus. The adult worms lay their eggs in the bronchioles and alveolar ducts. Many cats are asymptomatic with this disease.
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