Case Report
A 24-year-old woman presented with a 2-year history of a painless limp
on the left side requiring a walking stick to mobilise. Her medical
history included keratoconus associated with diabetes mellitus and
anxiety disorders, treated by Metformin (850 mg), Vildagliptin/Metformin
(50 mg/1000mg), and Fluoxetine (20 mg), respectively. The patient denied
any history of pain, loss of weight-appetite, fever, or family history
of cancer.
Radiological examination was conducted with hip X-ray revealed a large
aggressive tumour of the left hemipelvis. The tumour involved entirety
of acetabulum and extended to the sacroiliac joint. (Figure 1 ).
Magnetic resonance imaging (MRI) showed an extensive bone forming tumour
involving whole hemipelvis and eroding the hip (Figure 2 ).
There were no lung metastases. The patient underwent an open biopsy
through the ilioinguinal approach, and the diagnosis of a giant cell
rich telangiectatic osteosarcoma was made by the specialist sarcoma
pathology team.
The interdisciplinary sarcoma group recommended neoadjuvant
chemotherapy; MAP (methotrexate, doxorubicin, cisplatin) regimen was
given to the patient. The MAP regimen consisted of 120 mg/m2,
doxorubicin 37ยท5 mg/m2 per day on days 1 and 2 (on weeks 1 and 6)
followed 3 weeks later by high-dose methotrexate 12 g/m2 over 4 hours.
Sequential computed tomography (CT) indicated that the tumour did not
respond to chemotherapy and the tumour had increase in size, involving
the entire of the hemipelvis, the hip joint and crossed the sacroiliac
joint (Figure 3 ). External hemipelvectomy (left hindquarter
amputation) was performed in this case. Post-surgery, the patient
received adjuvant chemotherapy MAP (methotrexate, doxorubicin,
cisplatin) + Mifamurtide.
Histopathological examination of the resected specimen showed a large
malignant bone forming tumour, 20 cm x 25 cm x 16 cm, which partly
destroyed the ilium and widely invaded adjacent soft tissues
(Figure 4 ). The tumour surrounded the acetabulum, but did not
breach the articular surface, there was no involvement of the hip joint
or femur.
The tumour was relatively well circumscribed and mostly composed of
large cyst-like blood filled spaces lined by markedly pleomorphic tumour
cells and a small amount of bone and osteoid formation. Abundant
osteoclast-like giant cells permeated the tumour and septa
(Figure 5 ). The femur showed evidence of osteopenia.