CRYSTALLINE INCLUSIONS IN A SUBEPENDYMAL GIANT-CELL TUMOR IN A PATIENT WITH TUBEROUS SCLEROSIS

Unusual crystalline cytoplasmic inclusions were encountered in tumor c ells in a subependymal giant cell tumor (SEGT) in a 16-year-old girl w ith tuberous sclerosis. By electron microscopy, the tumor cells demons trated typical features previously described in SEGT, including abunda nt dense bodies, prominent Golgi complexes, abundant mitochondria, rou gh and smooth endoplasmic reticulum, scattered intermediate filaments and microtubules, glycogen, and rare synaptic contacts as well as prim itive intercellular junctions. The dense bodies were bound by a single membrane and were round, ovoid, irregular, or cylindric in appearance with electron-dense homogenous content or fingerprint profiles. Of no te was the presence of numerous cytoplasmic rhomboidal or rectangular crystalline inclusions akin to those seen in alveolar soft part sarcom a. These inclusions measured as much as 8 mum in length and had 7-nm p eriodicities, often with intersecting lamellae. Rarely, the membrane-b ound dense bodies showed areas of similar periodicities, indicating th at the crystalline inclusions are related to and might originate from the dense bodies. While crystalline inclusions have previously been de scribed in one patient with SEGT (Bender and Yunis, Ultrastruct Pathol 1980; 1:287-299), the inclusions in the present case were a striking feature and add to the spectrum of the ultrastructural pathology of SE GT.