Chondrosarcoma of the patella: A case report

Abstract

Rationale: Chondrosarcoma, characterized by the production of cartilage matrix, is a common bone tumor, accounting for 20% to 27% of all malignant bone tumors. It often occurs in the cartilage of the pelvis, femur, tibia, and humerus. However, chondrosarcoma of the patella is extremely rare.

Patient concerns: The present study describes a case of chondrosarcoma affecting the right patella in a 68-year-old woman. The chief complaints were painful swelling and limitation of motion of the right knee for about half a year. The pain was a kind of dull ache. The skin around the right knee was red and hot. Moreover, she had a claudication gait due to the symptoms.

Diagnoses: Irregular lytic lesions with ill-defined margins in the patella were determined through computed tomography and magnetic resonance imaging. The diagnosis of primary grade II chondrosarcoma was finally confirmed on the basis of postoperative pathological examination.

Interventions: The patient underwent an open surgery named extensive resection of patellar tumor to remove the tumor tissue completely.

Outcomes: The patient was discharged without any complications 1 week after the surgery. At the 3-month follow-up, the patient was completely free from pain during daily activities, and normal range of motion of the right knee was achieved. Her gait was normal. There was no evidence of recurrence.

Lessons: We believe that an extensive resection is suitable for treating chondrosarcoma to avoid as far as possible local recurrence. An awareness of the potential for chondrosarcoma to present in the patella is crucial for both orthopedic surgeons and radiologists when confronted with similar cases. Besides, as reports of chondrosarcoma of the patella are rare, this study adds a better understanding of this rare condition to the medical literature.

Figure 1

Lateral radiograph: multiple osteolytic lesions in the patella.

Figure 2

(A) CT: irregular lytic lesions on the patella. (B, C) Three-dimensional CT reconstruction: a few lytic lesions on the patella, resulting in rugged surface and edges.

Figure 3

Sagittal MRI with T1-weighting (A) and T2-weighting with fat saturation (B) diffusely abnormal marrow signal throughout the patella.

Figure 4

(A) A photograph: the removed tumor. (B) Hematoxylin and eosin stain: chondrosarcoma.