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Radiology

Case of the Month

Case No. : 13
Month : January
Year : 2000
Contributor :

Dr. Joshita Singh

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Clinical Profile :

An 18-year-old lady presented with right sided chest pain since 1 year associated with right sided chest wall swelling and low grade fever on and off since 2 months.

On inquiry, she also gave history of loss of weight, anorexia and occasional dry cough.A chest radiograph (Fig 1) was obtained. This was followed by a CT Scan(plain & contrast) of the chest (Fig 2a,2b)

Fig 1
Fig 1: A chest radiograph
Fig 2a Fig 2b
Fig 2a : CT Scan(plain) of the chest Fig 2b : CT Scan(contrast) of the chest

The chest radiograph shows a homogeneous, soft-tissue density mass opacifying the entire right hemithorax and causing a shift of the mediastinum to the left .No calcification is seen within the lesion. Relative enlargement of the right breast shadow is seen which shows a bulge on its lateral aspect. Closer inspection of the thoracic cage reveals a lytic non-expansile lesion of the right second rib with cortical thinning and no periosteal reaction. The left lung field is clear.

The CT Scan(plain & contrast) of the chest shows an inhomogeneous, soft tissue density mass lesion in the entire hemithorax extending into the adjacent chest wall and right breast causing enlargement of the right breast. No calcification is seen in the lesion which shows a variegated enhancement on post-contrast scans. Destruction of the entire right second rib is noted ; collapse of the underlying right lung is seen. Right pleural effusion with septations is seen. There is shift of the mediastinum to the left. The left lung is clear and there is no lymphadenopathy.

A biopsy of the lesion was done. This showed findings classical of an Ewings sarcoma.

Differential Diagnosis :

  1. Osteosarcoma :It is a strong differential as it has a similar clinical profile in terms of age of presentation and symptomatology. Osteosarcomas can also have a large soft tissue component. However rib is a rare site for an osteosarcoma. New bone formation is another differentiating feature.
  2. Pulmonary Pathology :On a chest film (which is the first imaging modality a patient is subjected to) patient's symptomatology and the predominant soft tissue component may simulate an intrapulmonary pathology. However demonstration of rib destruction will rule this out. Rib involvement in a Pancoast's tumor is via an extrinsic erosive process of remodelling or frank erosion.
  3. Malignant mesothelioma invading the rib : This affects elderly patients and those with prolonged exposure to asbestos.
  4. Osteomyelitis :soft tissue component will be not be so prominent.
  5. Early in the course of the disease, some of the other differentials will be eosinophilic granuloma (no soft tissue component), fibrous dysplasia (expansile lesion), metastasis (affects elderly age group) and neuroblastoma (affects younger patients).

Discussion :

Introduction :Identified in 1921 by James Ewing, Ewing`s Sarcoma is a highly malignant bone tumor characterized histologically by small round tumor cells.

Clinical characteristics :It primarily affects young people (adolescents & young adults ) and shows a male predominance with a male to female ratio of 2:1.The patient typically presents with pain &/or a soft tissue swelling .Fever, cough, or a pathological fracture may also bring the patient to the doctor.

Location :Ewing`s sarcoma commonly arises from long tubular bones(50-60%) especially the femur, tibia & humerus. The next common sites of origin are the flat bones(40%) especially the innominate bones, the ribs & scapula. The incidence of Ewing`s sarcoma in a rib is approximately 11%.

Radiological Features : A majority of the Ewing`s sarcoma of the rib are predominantly lytic lesions. However there may be mixed lytic and sclerotic or predominantly sclerotic lesions. The chest radiograph may show the rib lesion to be lytic with cortical thinning or densely sclerotic with cortical thickening and obliteration of the medullary cavity or there may be permeative bone destruction. A striking feature of Ewing`s sarcoma of rib is the accompanying soft tissue involvement which may be markedly disproportionate to the intraosseous involvement of the tumor. The tumor growth direction tends to be intrathoracic so that the intrathoracic component is much larger than the extrathoracic component. Another characteristic feature is the minimal periosteal reaction seen with these lesions. CT or MRI will delineate the extent of the lesion. On MRI the tumor shows intermediate signal intensity on T1-weighted images and increased signal intensity on T2-weighted images

Treatment :Chemotherapy and Radiation-therapy in combination with surgery when possible .
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