Cytoplasmic P53 Immunostaining With N-Terminus P53 Antibody And Absence Of Staining With C-Terminus P53 Antibody: A Report Of Two Pediatric Sarcomas With Distal Truncating Mutations Affecting Nuclear Localization Domain.

P53 immunohistochemical staining with antibodies targeted to epitopes at or near the N-terminus are commonly used in diagnostic pathology practice as a surrogate for mutations. The abnormal staining patterns indicating mutations include nuclear overexpression, null, and the recently described cytoplasmic staining. The latter staining pattern occurs with the less common mutations affecting its nuclear localization and/or tetramerization domains that are located toward the C-terminus. Here we describe the first two cases of pediatric sarcomas with cytoplasmic staining with P53 antibody against N-terminus epitope and the absence of staining with P53 antibody against C-terminus epitope. We propose that a more precise description of P53 immunohistochemical staining patterns should include the nature of the antibody used.