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Case 382


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A 17-year-old female presents to the office complaining of dull right knee pain, which she relates to a lesion provoked by falling from height. History of a similar episode 4 months ago, when was prescribed common analgesia. She had good initial response, although, the symptoms recurred, with a progressive worsening of the pain, despite the analgesia. Physical exam shows right knee effusion and discrepancy between tights’ circumference. Plain radiograph of the tight and right knee pointed a non-specific subperiosteal thickening. Magnetic resonance imaging (MRI) was performed (images 1 to 3).

Considering the case report and the findings on the MRI, which is the most adequate approach in this moment?

a) Perform excisional biopsy of the lesion to diagnose the bone tumor


b) Communicate the suspicion of malignancy to the family, perform incisional biopsy of the lesion and the following exams: complete blood count, CRP, hepatic and renal function panels and serum electrolytes


c) Communicate the suspicion of malignancy to the family and transfer the patient to a referral hospital, where the diagnostic workup and management of the bone tumor will take place


d) Ask a computed tomography (CT) with the purpose of locally staging the tumor, communicate the suspicion of malignancy to the family and ask them to look for an orthopedic oncologist


Image analysis

Image 1: Magnetic resonance image of the right thigh, T1-weighted, coronal view. Presence of an expansive and heterogeneous lesion (marked in red). T1-weightening shows areas of low signal intensity related to the substitution of the medullary cavity by osteoid. There are soft tissue components inside the bone and in the adjacent tissue, with an intermediate signal (better viewed with T2-weightening – image 3)


Image 2: Contrast-enhanced magnetic resonance image of the right thigh, coronal view, T1-weighted. The lesion enhances heterogeneously by the contrast agent; this is viewed in the medullary component (dark red) and in the adjacent soft tissue (light red). There are hypoenhancing areas, probably related with necrosis (the most visible ones are marked in blue). The bone cortical presents irregularities, with some poorly defined areas.


Image 3: Magnetic resonance image of the right thigh, T2-weighted, coronal view. The medullary cavity presents heterogeneous high signal, involving the diaphysis, metaphysis and epiphysis (dark red) and in the adjacent soft tissue (light red); it is related with effusion and tumor infiltration. The areas probably associated with necrosis are marked in blue.



- Primary osteosarcoma is the most common primary sarcoma in children and adolescents. Its incidence peak is in between 13 and 16-year-old;

- There may be a relationship between rapid bone growth and the development of this neoplasm;

- The most common clinical findings are localized pain, soft tissue mass, effusion and antalgic gait;

- Diagnostic workup initiates with plain radiograph. Staging workup is imperative; MRI is essential for local staging. Other image modalities, as CT and PET/CT, are used for systemic staging.

- The main sites of metastasis are the lungs and other bones;

- Biopsy is necessary for definitive diagnosis. Treatment is based on surgery associated with neoadjuvant and adjuvant chemotherapy. Preoperative size reduction with chemotherapy is an important prognosis factor.



Letícia de Melo Elias, 5th year medical student at Federal University of Minas Gerais School of Medicine (UFMG).

Mail: letimelo02[at]



Adriana Teixeira Rodrigues

Pediatrician and professor at the Department of Pediatrics at UFMG.

Mail: adrianatr92[at]


Júlio Guerra Domingues

Radiologist and professor at the Department of Anatomy and Image at UFMG.

Mail: ituliob[at]



Aristeu Fonseca, Mariana Dinamarco Mestriner, Leandra Prates Diniz, Rafael Arantes, Rafaela Furtado


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