Gross & Microscopic Description -- Echogenic Mass in Third Ventricle


At postmortem examination, the infant had generalized edema. The head was enlarged (crown-rump length, 28 cm; head circumference, 42 cm) (Fig. 4). The lungs showed evidence of mild hyaline membrane disease. Extensive acute tubular necrosis of the kidneys was also seen. The placenta showed extensive edema, chorionitis, villitis, and prominent syncytial knots. The brain weighed 315 gm (expected for body size, 180 +/- 34 gm) and had marked distortion of the architecture. Fibrous adhesions were seen between the brain, leptomeninges and dura (Fig. 5). There was severe hydrocephalus affecting the lateral, third and fourth ventricles. The cerebral hemispheres were massively dilated, with only a thin rim of apparent cortical tissue (Fig. 6). Beneath this rim was a mass composed of blot clot and soft, pale tissue measuring approximately 10 x 6 x 3 cm. The exact site of origin of this tumor was unclear due to extensive destruction of adjacent structures. The brainstem and cerebellum appeared orange-stained, rubbery and firm (Fig. 7).

Histologic examination showed neoplastic tissue involving lateral and third ventricles, supratentorial brain parenchyma (Fig. 8) and meninges (Fig. 9). The neoplasm was highly cellular, composed of small round to ovoid cells with hyperchromatic nuclei and little cytoplasm (Fig. 10). Some areas exhibit more compact spindle cells (Fig. 11). Mitotic figures and pleomorphism were not prominent (Fig. 12). Occasional pseudorosettes were seen (Fig. 13). There was extensive hemorrhage (Fig. 14) with areas of necrosis surrounded by multinucleated giant cells (Fig. 15). The tumor cells expressed S-100 (Fig. 16) and focally, synaptophysin and GFAP. Cerebellum was not involved by tumor (Fig. 17).



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