Soft tissue gliomatosis. Morphologic unity and histogenetic diversity.

ABSTRACT

Normal-appearing tissues in non-native sites constitute one of the more common morphologic expressions of abnormal development. The presence of pancreas in the wall or on the serosa of the small intestine and adrenal cortical tissue in a hernia sac are two familiar examples of heterotopias. We report our experience of mature glial tissues in the soft tissues of six children who were between the ages of 4.5 months and 2 years when they presented with a solitary mass on the chest wall (three cases), scalp (two cases) and gluteal region (one case). These tumors were all characterized by pale-staining fibrillary foci of mature neuroglia, which were intensely immunoreactive for glial fibrillary acidic protein in each case. One of the two scalp lesions was accompanied by a nodule of cartilage and a meshwork of pseudovascular spaces, which were decorated with antibodies to vimentin and epithelial membrane antigen consistent with meningothelial tissue. The histogenesis of the neuroglial tissue in the gluteal region and scalp was, respectively, on the basis of a recurrence of a sacrococcygeal teratoma in the former case and sequestered encephaloceles in the last two cases. A facile explanation for the occurrence of neuroglial tissue in the soft tissue of the chest wall in the remaining three cases was less than obvious as none of the patients had accompanying neurologic or anatomic defects and all were in a nonmidline location. These three cases of soft tissue gliomatosis of the chest wall are similar to an earlier example in the recent literature whose histogenesis was as enigmatic as it proved to be in our three cases. Although the histologic and immunohistochemical features of these six cases were very similar in each instance, their origin varied from a recurrent sacrococcygeal teratoma and sequestered encephaloceles to essentially unknown.