1. Interactive Case Tutorial

2.  Review the history and signalment for the client  Evaluate the radiographs provided  Explore the interactive images and compare the answers given with your own interpretations. When you’ve clicked on the image, click the same spot again to make the label disappear.  Answer the questions regarding a diagnosis and recommendations  Review the radiologist’s findings

3.  Signalment: 14 year old, MN, DSH  History: swollen and painful right carpus; non- weight bearing right thoracic limb; treatment with antibiotics, prednisone and pain medication have provided no benefit  Study: lateral and dorsopalmar views of the right manus

4. Circumferential spiculated periosteal reaction on 3 rd metacarpal bone Solid periosteal reaction on 4 th metacarpal bone (abaxial) Marked extracapsular soft tissue swelling Spiculated periosteal reaction on 3 rd metacarpal bone

5.  Provide a diagnosis based on your findings. Submit There is an aggressive lesion of the third metacarpal bone with associated soft tissue swelling. Differentials include neoplasia (metastatic or primary bone tumor, soft tissue neoplasia) and osteomyelitis (fungal or bacterial). The reaction on the fourth metacarpal bone is thought to be secondary to the swelling (reactive periostitis) Feedback Continue

6.  Provide your recommendation for this client. Submit Careful physical examination to assess for evidence of puncture wound. Fine-needle aspirate or biopsy of the third metacarpal bone. Thoracic radiographs for staging given the possibility of neoplasia Feedback Continue

7.  Centered at the mid metacarpus is marked extracapsular soft tissue swelling  The third metacarpal bone has marked spiculated periosteal reaction along the entire diaphysis  No definitive lysis of the third metacarpal bone is identified  The fourth metacarpal bone has a solid periosteal reaction on the abaxial cortex

8.  Biopsy of the third metacarpal bone: carcinoma with desmoplasia  Comments: the origin of the carcinoma is not clear; metastatic pulmonary adenocarcinoma should be considered

9. Soft tissue mass in the right cranial lung lobe

10.  Provide a diagnosis based on your findings from the thoracic radiographs. Submit The most likely differential is a primary lung tumor (for example, bronchogenic or bronchoalveolar adenocarcinoma). Less likely consideration is given to a large, solitary metastatic lesion Feedback Continue

11.  The right cranial lung lobe mass was sampled (fine-needle biopsy) with ultrasound guidance  Cytology: carcinoma, most likely primary lung tumor