Case No. :	60
Month :	December
Year :	2003
Contributor :	Dr. Vidyadhar Suryakar

Other Cases

A four and a half year-old-boy presented with complaints of low grade, continuous fever and dry cough since one month. This was associated with gradually increasing breathlessness. On clinical examination, the air entry was absent on the right side. Based on the initial interpretation of the chest radiograph, a right pleural effusion was tapped; but, there was no improvement in the clinical condition of child. Three weeks after the onset of the first symptoms, the child developed weakness of both lower limbs.

The ESR was 48mm at the end of first hour. The TLC was 10600cells/cmm (P-48%,L-51%,E-1%), Microscopic examination of the smears of pleural fluid prepared after cytocentrifugation showed few RBCs, occasional mesothelial cells, but no malignant cells.


RADIOLOGICAL FINDINGS:

The frontal projection of the chest radiograph shows a homogenous soft tissue shadow in the right hemithorax with shift of the mediastinum to the opposite side.. The density of the opacity is most marked in the mid-lower zone with the costophrenic angle being relatively less dense. There was no evidence of bone destruction. In view of this a loculated collection or a mass was suspected and a CT of the thorax was performed.

Fig.1

The plain and post contrast computed tomography of thorax showed multiple, bulky lobulated, inhomogenously enhancing masses within the right hemithorax causing displacement of the heart and the mediastinum to the left. The lesion insinuates into the lung bases between the right lobe of the liver and the parietal wall. There is a right hydropneumothorax. The fat planes adjacent to the mediastinal structures, the heart and the right dome of the diaphragm appear effaced. The lesion surrounds about half the circumference of the thoracic aorta. The left lung parenchyma shows no evidence of focal pathology. Intraspinal extension of the mass with resultant cord compression is seen at the mid dorsal level. There is lytic expansion of the vertebral end of the fourth rib on the right side. Extension of the lesion into the adjacent back muscles is seen. The visualised upper abdominal structures appear unremarkable.

Fig.2	Fig.3
Fig.4

An MRI of the dorsal spine was performed to better evaluate the intraspinal extension.

This showed an intermediate signal intensity soft tissue lesion on T1W images in the right lateral and posterior epidural space between D5 and D8 levels. The lesion turns heterogeneously hyperintense on the T2W images. The dorsal spinal cord over these levels is compressed and displaced antero-laterally and to the left. Moderate cord edema is seen. There is extension of the lesion in the posterior paraspinal region. A large soft tissue lesion is seen to occupy nearly the entire right hemithorax and extend into the prevertebral region and partly encase the descending thoracic aorta. The mediastinum and vascular structures are displaced anteriorly and to the left with loss of fat planes between the lesion and the mediastinum. The carina is also displaced anteriorly and to the left of midline. The visualised dorsolumbar vertebral bodies and intervertebral discs reveal normal signal intensity.

Fig.5	Fig.6
Fig.7

These radiological features were thought to represent a neoplastic process - a round cell tumor - such as Ewing's sarcoma, Askin's tumor, Non Hodgkin's lymphoma etc.

PATHOLOGICAL FINDINGS:

Histopathological study of the biopsy from the mass lesion showed a strip of edematous stromal tissue containing compact groups and large contiguous sheets of small round undifferentiated malignant cells. The nuclei were dense hyperchromatic and irregular. The differential diagnosis being Ewing's sarcoma, Askin's tumor, PNET.

DISCUSSION:

Malignant round cell tumors of the bone comprises Ewing's sarcoma, peripheral neuroectodermal tumors, primary lymphoma of bone and metastatic neuroblastoma. Cytogenic analysis shows a specific constant reciprocal translocation between chromosomes 11 and 22 which is shared with extraskeletal Ewing's, PNET and Askin's tumor.

Ewing's sarcoma is a rare, highly malignant primary neoplasm of bone. 75% of patients are under the age of 20yrs. The male:female ratio is 2:1.Usually a single bone lesion is involved - but multiple lesions do occur . Commonest sites are femur, tibia, humerus as well as marrow rich sites such as pelvis and ribs. The neoplasm is usually medullary in origin. The bone lesion is destructive in pattern; early lesions in the medulla may be very ill-defined, allowing periosteal reaction to be visualised but extension tends to occur along the length of marrow. Classical findings of saucerisation and onion peel appearance are common. The commonest sites of metastases are the lung and bone.

Askin's tumor is rare, malignant, small, round cell tumor of thoracopulmonary region usually occurring in children and young adults. Radiologically 70% patients present as pleural disease with a soft tissue mass involving the chest wall.

Primitive neuroectodermal tumors of bone resemble Ewing's sarcoma clinically except that they are common in the female sex. They are destructive, ill-defined neoplasms which readily spread into soft tissues .

Primary malignant lymphoma of bone (a form of non-Hodgkins lymphoma, usually B cell) is a rare skeletal neoplasm. The age limit is wide from the second to the eighth decade with peaks around 20& 50yrs .They uncommonly affect children. The male:female ratio is 1.6:1.

In the pediatric age group, large pleural effusions should be viewed with grave suspicion as they often represent pleural masses of malignant origin associated with pleural effusion

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