PIK3CD and histiocytic sarcoma: The PI3K/Akt pathway is commonly activated in cancers [28], and somatic mutations in PIK3CD and PI3KCA, which encode other PI3K isoforms, have recently been detected in a subset of primary human histiocytic sarcoma tumors as well as secondary tumors and their co-occurring lymphomas [3,37], although mutations in PI3Kγ genes have not yet been reported.