PMC5791238_01
(a) Initial plain radiograph of the knee anteroposterior and lateral views showing an eccentric lytic lesion involving the epiphysis of right proximal tibia in keeping with chondroblastoma (white arrow) (b) Plain radiograph of the knee 5 years after the initial surgery showing a lytic lesion adjacent to previous bone cement in keeping with local recurrence of chondroblastoma (white arrow) (c) Coronal T2 weighted magnetic resonance image showing a heterogenous hypodense lesion at the metaphyseal region (red arrow) of right proximal tibia adjacent to previous cement (green arrow). (d) Plain radiograph of right knee post repeat curretage and polymethyl methacrylat cementation (e) X-ray of knee joint with leg bones anteroposterior view showing proximal tibia endoprosthesis
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PMC5791238_01_IJOrtho-52-87-g001.jpg
F1
The plain radiograph showed an eccentric lytic lesion over the epiphysis of right proximal tibia [Figure 1a]. Plain radiograph revealed a lytic lesion just adjacent to previous PMMA cement in keeping with local recurrence [Figure 1b]. Magnetic resonance imaging showed a homogenous lesion adjacent to the previous bone cement [Figure 1c]. Repeat curettage with bone cementation was done [Figure 1d] for the lesion. He further underwent proximal tibia wide resection with endoprosthesis reconstruction and medial gastrocnemius flap followed by adjuvant chemotherapy [Figure 1e].
Histopathology of slides showing (a) Uniform and cellular chondroblastic proliferation with calcification. (black arrow). (b) Areas with chicken wire calcification suggestive of chondroblastoma (black arrow). (c) Histiocytic-like cells displaying nuclear groves (black arrow). (d) The tumour consists of predominantly epithelioid cells exhibiting vesicular nuclei, clumped chromatin, prominent nucleoli and moderate amount of pale to eosinophilic cytoplasm. (e) Areas of lace like osteoid deposition with irregular mineralisation
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PMC5791238_01_IJOrtho-52-87-g002.jpg
F2
The final diagnosis remained as chondroblastoma [Figure 2a-c]. The resected specimen was send for histopathology and margins and revealed a high-grade conventional osteosarcoma [Figure 2d and e] with close margins.