Osteosarcoma of Distal Femur Presenting As Giant Cell Tumor: A Case Report - Cureus

The astir predominant benign bony tumour, known arsenic a elephantine compartment tumour, usually appears successful the property radical of 20-30 years. It often happens successful the epiphysis-metaphyseal portion of agelong bones. The distal femur and proximal tibia are the astir often encountered sites, followed by the distal radius [1]. Despite being benign, the lesion is assertive locally and has the imaginable to invade adjacent brushed tissues. Histologically, the mononuclear cells that marque up the elephantine compartment tumour are dotted with multinucleated ample cells. The biologic behaviour of the tumour and its histological quality whitethorn not needfully correlate. Surgery has mostly been considered the champion people of treatment. The tumour tin beryllium removed either done en bloc excision oregon intralesional curettage. The extremity of attraction is to support relation portion reducing the likelihood of recurrence [2]. The likelihood of a recurrence is influenced by the grade of curettage and tumour features, including tumour tract and size. Receptor-activated atomic origin Kappa is expressed by the multinucleated elephantine compartment tumour (RANK). The mesenchymal crab cells nutrient RANK ligands. The enactment of these RANK-RANKL triggers the differentiation of neoplastic cells successful elephantine compartment tumours, which gives the tumour its assertive quality and destroys bony [3,4]. Recently, denosumab therapy has been suggested to dainty bony elephantine compartment tumours. A humanized monoclonal antibody called denosumab blocks the RANK-RANKL connection, preventing tumour differentiation. Most of these malignant changes happened erstwhile tumours recurred pursuing radiation therapy, denosumab therapy, oregon surgical curettage [5,6].

Rarely are determination reports of superior bony elephantine compartment tumours that person undergone high-grade malignant translation without having antecedently had surgery, radiation therapy, oregon denosumab therapy. Some publications person referred to this lawsuit arsenic bony elephantine compartment tumor (GCT) dedifferentiation [3,7]. However, determination is precise small grounds to enactment this theory. A much communal mentation disposable successful the lit is that malignant GCT often contains areas of accepted GCT. The archetypal biopsy could person been taken from these sites, and the diagnosis could person been missed. In this lawsuit report, we contiguous a diligent who complained of genu symptom and swelling for 1 twelvemonth earlier visiting the tertiary attraction hospital. The X-ray of the distal femur showed a lytic lesion. The MRI suggested an aneurysmal bony cyst oregon consequent modifications of an aneurysmal bony cyst successful a elephantine compartment tumour. A benign elephantine compartment tumour of the bony without sarcomatous characteristics was discovered during an incisional biopsy. After being removed 2 weeks later, the tumour revealed sections of high-grade osteosarcoma and benign GCT.

A 25-year-old antheral diligent arrived astatine the Acharya Vinoba Bhave Rural Hospital (AVBRH) complaining of discomfort and swelling successful his near genu for 1 year, which had worsened during the erstwhile month. A widespread, poorly defined enlargement measuring 6 x 4 cm was seen during a objective introspection implicit the near lateral femoral condyle. Anteroposterior and lateral genu views connected a plain radiograph revealed a lytic lesion successful the lateral condyle of the femur (Figures 1, 2).

The diligent was admitted with a presumptive diagnosis of either a elephantine compartment tumour oregon an aneurysmal bony cyst. An MRI of the near genu was performed, and the results suggested either an aneurysmal bony cyst oregon consequent alterations of an aneurysmal bony cyst successful a elephantine compartment tumour. The lesion was highly defined, expansile, multilobulated, and had aggregate fluid levels (Figures 3, 4).

On June 23, 2022, an incisional biopsy nether spinal anaesthesia was carried out. Slides from the biopsy revealed sections of aneurysmal bony cysts (ABC) with a batch of hemosiderin pigment, bland stromal cells, and osteoclast-like cells (Figures 5, 6). All of these characteristics pointed to the aneurysmal bony cyst. There were nary pleomorphic oregon hyperchromatic lesions, antithetic mitoses, oregon cellular atypia.

Two weeks later, the diligent was managed with curettage and interior fixation with sheet osteosynthesis (Figures 7, 8). A bony graft filled the ample bony defect from the iliac crest. The samples were sent for a histopathology examination. The study suggested osteogenic sarcoma oregon malignant translation of elephantine compartment tumours. Sections from the insubstantial showed osteocartilagenous insubstantial with a tumour rim showing malignant spindle cells with ample nuclei, nucleoli and abnormal chromatin clumping on with elephantine cells, affirmative for infiltration by malignant cells connected histopathology. There were besides highly atypical mitoses, up to 5-10 per precocious powerfulness tract (Figure 9). The diligent was past planned for chemotherapy aft 28 days of excision.

Although elephantine compartment tumours are often found, they seldom go malignant. The word "primary malignant elephantine compartment tumour" refers to a malignant bony tumour with sections of emblematic benign compartment tumour interspersed passim and has ne'er undergone curettage oregon radiation therapy. Usually, with a anterior past of radiation therapy, curettage, oregon excision, the operation secondary malignant elephantine compartment tumour of bony is utilized to picture a malignant bony tumour that exhibits sarcomatous maturation astatine a spot wherever it was antecedently reported arsenic a benign elephantine cell. The causes of consequent malignant elephantine compartment tumours of the bony that make aft radiation and curettage person been the taxable of assorted theories [1,3,6]. Sakkers et al. projected a mentation which stated that post-curettage malignant translation of GCT of bony was owed to the proliferative changes astatine the margins of a dormant bony which serves arsenic a stimulus for the enactment of a malignant tumour [2].

Brien et al. [1], successful their report, authorities that determination beryllium 3 antithetic compartment lines successful a elephantine compartment tumour of bone. First, mononuclear spindle cells acquisition proliferation successful culture; second, non-spindle mononuclear cells bash not proliferate successful culture. Third, multinucleated elephantine cells are akin to osteoclasts and are formed owed to the conjugation of mononuclear stromal cells. The mononuclear cells and elephantine cells are derivatives of the haematopoietic system. They authorities that retired of these 3 compartment types, astatine slightest 1 is derived from the mesenchymal system, which is astir apt to beryllium the mononuclear spindle cells owed to their quality to proliferate successful civilization [1,3]. A elephantine compartment tumour is frankincense a substance of cells that are derived from haematopoietic arsenic good arsenic mesenchymal origin. This explains the occasional conversion of a elephantine compartment tumour into osteogenic sarcoma.

Various studies of malignant translation of elephantine compartment tumours conducted antecedently person reported either a erstwhile past of radiotherapy, curettage oregon a malignancy which occurred astir 1.7 to 15 years aft attraction of elephantine compartment tumour [4,6,7]. Boriani et al. studied 327 elephantine compartment tumours and observed 10 cases of malignant transformation. Out of these, 8 cases had a past of erstwhile radiotherapy oregon curettage and 2 cases transformed into sarcoma aft galore years of attraction [5,8,9]. A elephantine compartment tumour that has been malignant from the opening is highly rare. In this case, the diligent gives a past of complaints for lone 1 year, which got aggravated implicit the past month. The objective findings, x-rays, and MRI studies suggested an aneurysmal bony cyst oregon secondary changes of aneurysmal bony cyst successful a elephantine compartment tumour. The biopsy specimen findings were accordant with these findings. However, aft the implicit excision of the tumour, a sarcomatous constituent was besides interspersed with benign tumour cells. Thus the tumour was malignant from the beginning, an infrequent occurrence. This tin beryllium explained by the anticipation of the biopsy being taken from a tract that was not typical of the tumour. This tin hap owed to the beingness of areas of accepted GCT interspersed wrong osteosarcoma, which often makes the diagnosis difficult. Hence, the superior malignant elephantine compartment bony tumour often mimics GCT clinically and radiographically.