Contributed by Pai Balaji S1, Nithyananda Shetty2, Anita Mahadevan 3, S.K. Shankar3
Departments of Neurosurgery1 and Cardiothoracic surgery2, M.S. Ramaiah Medical College, Bangalore, India
Department of Neuropathology3, National Institute of Mental Health and Neurosciences, Bangalore, India
A 21 month old female child of non consanguineous parentage was admitted to the neurosurgical unit with rapidly progressing spastic paraparesis of lower limbs, following a febrile episode of 20 days duration. The developmental milestones were normal, with no history of trauma or any significant illness or hospitalization in the past. MRI of the dorsal spine revealed a large T1 - T4 right paravertebral circumscribed mass with intraspinal extension and severe cord compression suggestive of a neurofibroma with dumb-bell shaped intra and extraspinal extension (Fig. 1 and 2). On ultrasound examination there was no evidence of an abdominal mass. The tumor was approached through a right posterolateral thoracotomy. A greenish pink tumor adherent to the parietal pleura and right T2 - T4 intercostal nerves, vagus nerve and extending as small lobules into the tracheo- esophageal groove and carina was excised, leaving a small portion adherent to the vessels. Resecting the posterior ends of second, third and fourth ribs on the right and nibbling the vertebral pedicles from T1 - T4, the intraspinal portion of the lesion was totally resected. Post operatively the child had chylothorax that regressed spontaneously after 4 weeks. Chemotherapy was advised, but the parents refused. On follow up after one year, the child had regained normal power of lower limbs, but had mild spasticity. A repeat MRI after one year revealed no increase in size of the residual lesion and no evidence of metastatic disease anywhere (Fig. 3).
Histological examination revealed a highly cellular, mitotically active neoplasm, fairly circumscribed except for finger like extensions into the surrounding soft tissues. Thick fibrocollagenous septae divided the tumor into grossly apparent lobules, populated by uniform small, dark, round-to-oval cells with hyperchromatic nuclei and scant cytoplasm, which were grouped around a fibrillar matrix forming large rosette like structures (Fig. 4 and 5). Interspersed were larger, immature cells having single, double or multiple nuclei with prominent nucleoli and variable amounts of eosinophilic cytoplasm (Fig. 5, insert). Small pockets of calcification and necrosis were found. At the periphery, close to capsule were few remnant mature neurons of the sympathetic ganglion of the posterior mediastinum. There was no schwannian/ stromal component in the tumor.
The highly differentiated zones marked by dense fibrillar matrix and rosette like structures were labelled strongly by synaptophysin (Fig. 6). The small undifferentiated tumor cells exhibited strong immunopositivity only for neuron specific enolase (NSE) (Fig. 7). The larger immature cells with prominent nucleoli, showed accumulation of neuroepithelial progenitor cell-intermediate filament marker, nestin (Fig. 8) in addition to other markers including cytoplasmic localization of synaptophysin (Fig. 9), neurofilament (Fig. 10) and NSE (Fig. 11). This contrasted with the mature ganglion cells of sympathetic ganglion at the capsular zone in which synaptophysin labelling was restricted to the cell membrane decorating the synaptic boutons (Fig. 12).