Comparative study of soft tissue perineurioma and meningioma using a five-marker immunohistochemical panel

Aims: Owing to their close embryological relationship, soft tissue perineurioma and meningioma may closely mimic each other, not only histologically but also by immunohistochemistry. We aimed to compare the frequency of perineurial marker expression in these two entities, and to determine whether somatostatin receptor 2 (SSTR2) and progesterone receptor (PR), both expressed frequently in meningiomas, are also expressed in perineuriomas. Methods and results: We analysed and compared the immunohistochemical findings in 58 WHO grade I meningiomas (29 meningothelial, 16 fibrous, 10 transitional, and three others), 10 WHO grade II (atypical) meningiomas, and 20 soft tissue perineuriomas. All tumours were stained using five antibodies against antigens that are known to be expressed in perineuriomas or meningiomas: epithelial membrane antigen (EMA), claudin-1, GLUT-1 (glucose trans-porter-1), SSTR2, and PR. Of the meningiomas, EMA was expressed in 59 of 61, claudin-1 in five of 63, GLUT-1 in 19 of 62, SSTR2 in 59 of 68, and PR in 44 of 62. Of the perineuriomas, EMA was expressed in 20 of 20, claudin-1 in 17 of 18, GLUT-1 in 14 of 16, SSTR2 in one of 20, and PR in one of 20. The SSTR2-positive/PR-positive phenotype was detected in 42 of 60 meningiomas, but in none of 20 perineuriomas. On the other hand, the claudin-1-positive/GLUT-1-positive phenotype was detected in only four of 62 meningiomas, and in 14 of 16 perineuriomas. Conclusions: Epithelial membrane antigen expression is ubiquitous in both entities, and does not distinguish between them. SSTR2 and PR are highly sensitive and, in this context, specific meningioma markers. They may be helpful in distinguishing between the two entities, particularly in cases of meningioma occurring at unusual (extracranial) sites.