The last case of the year is 10-year-old male Boxer with swelling on the thoracic wall and right thoracic limb. What are your findings and differential diagnoses?
FindingsThere are multiple thickened regions of soft tissue surrounding the right carpus. Many of these swellings have air-filled cavities on the surface indicating ulceration. There is irregular to pallisading periosteal new bone formation along the medial aspect of the proximal phalanx of the second digit. The phalanx of the first digit is irregularly margined and tapers to a sharp osseous projection, with a small mineral opacity seen just distal to this phalanx. There is smoothly margined periosteal new bone formation along the medial aspect of the mid-diaphysis of the right 3rd metacarpal bone. There is also smoothly margined, periosteal new bone formation along the mediocaudal aspect of the distal radial diaphysis.
Differential DiagnosisThe soft tissue changes are consistent with neoplasia, likely an additional site to that seen on the thoracic wall. The ulceration may have resulted in osteomyelitis, or periostitis of the adjacent bone. Neoplastic extension into the bone could also be considered.
- Non-epitheliotrophic cutaneous T-cell lymphoma (large cell)