Wiktoria Jamont 1, Maciej Krukowski 2, Janusz Jaworski 2, Naomi Earley 1
Background
Retained cartilage cores (RCCs) are developmental anomalies commonly affecting the distal ulna in young dogs, typically characterized by well-defined, radiolucent metaphyseal lesions. This case report describes an atypical presentation of RCCs associated with a femoral Salter–Harris type III fracture in a Flat-Coated Retriever. The study highlights the diagnostic complexity when RCCs present with aggressive imaging features that mimic neoplasia or infection.
Methods
A 9-month-old male Flat-Coated Retriever with chronic right pelvic limb lameness post-trauma was evaluated using radiography and contrast-enhanced computed tomography (CT). Additional diagnostics included synovial fluid cytology, hematologic and biochemical profiles, and a surgical bone biopsy. Following imaging and diagnostic assessments, a femoral head and neck ostectomy (FHO) was performed, with histopathological analysis of resected tissue.
Results
Radiographs and CT revealed a right proximal femoral Salter–Harris type III fracture with mixed geographic and ill-defined lysis in the adjacent metaphysis, widening of the joint space, and mineralized fragments. Histopathology confirmed retained cartilage cores characterized by disorganized clusters of chondrocytes and periosteal resorption, without evidence of inflammation or malignancy. Follow-up at 12 weeks postoperatively showed significant clinical improvement with reduced lameness and increased muscle mass.
Limitations
This is a single case report, limiting generalizability. The unusual presentation of RCCs made initial diagnosis challenging, especially given the breed's predisposition to neoplasia. Further, the case underscores the need for a potential classification system for atypical RCC presentations.
Conclusions
RCCs can present atypically with imaging features that mimic aggressive pathologies such as neoplasia or osteomyelitis. This case emphasizes the importance of histopathology for definitive diagnosis. RCCs should be considered a differential diagnosis for metaphyseal lytic lesions in young dogs, particularly when standard features are absent.
Ventrodorsal extended (A) and frog-leg (B) view radiographs of the coxofemoral joints. Black arrows show the poorly defined and heterogeneous proximal right femoral physis. White arrows demonstrate ill-defined lysis. Black oval outlines a suspected bony fragment at the dorsal margin of the right proximal femoral physis and epiphysis.
How did we do?
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