LAUSR

Malignant mesothelioma (MM), the primary cancer of the mesothelium, is characterized by dismal prognosis. However, there are other forms of primary mesothelial tumors, which are benign, the adenomatoid tumors (AT) and the well-differentiated papillary mesothelial tumor (WDPMT, formerly called well-differentiated papillary mesothelioma) (1). Interestingly, two recent studies showed that both ATs and WDPMTs harbor mutations in the TRAF7 (2,3), suggesting a possible pathogenetic link between them (1). The authors further proposed that as a possible consequence of this mutation, the L1 cell adhesion molecule (L1CAM), should be expressed in these lesions (2,3). Indeed, after performing immunohistochemistry for this marker, they showed L1CAM expression in both ATs and WDPMTs. Another lesion that could enter the family of benign mesothelial lesions, is the so-called "multicystic mesothelioma" (4). The exact nature of this lesion, reactional or neoplastic, has been a matter of debate since decades, and their varied terminology does prove the uncertainty (4). Given their common mesothelial origin, we aimed to explore the possible expression of L1CAM in a large series of cystic mesothelial lesions.