Annals of diagnostic pathology
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Benign peripheral nerve sheath tumors (PNSTs) showing more than one line of differentiation (hybrid PNSTs) have been increasingly recognized, mainly due to awareness of their existence and as a consequence of increased use of immunohistochemisty during the last decade. Two recent studies suggested overrepresentation of hybrid tumors among benign PNSTs in patients with neurofibromatosis type 1 (NF-1). This study was performed to assess the presence of perineurial cells in microscopic (early) neurofibromatous lesions and normal-looking peripheral nerves in specimens from 5 patients with NF-1 using markers of perineurial cell differentiation (epithelial membrane antigen, claudin-1, and glucose transporter 1). ⋯ Both patients had concurrent multiple larger PNSTs (plexiform neurofibromas, hybrid neurofibroma/perineurioma and lesions with features intermediate between the 2 types). One specimen harboring high-grade malignant PNST and 2 specimens with large solitary neurofibromas displayed no intraneural perineurial cells. These observations suggest that intraneural perineurial proliferations are part of the early lesions in the setting of constitutional NF-1 inactivation and support the concept of pure and hybrid perineuriomatous lesions as novel member of the spectrum of PNSTs in NF-1.
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Intraosseous hibernoma is a rare benign bone tumor, with only 3 cases reported in English literature. In this report, we describe a 50-year-old woman with a history of stage IIB breast cancer and posterolateral right hip pain. Imaging studies showed a sclerotic lesion in the right ilium, which was biopsied and showed mildly thickened bone trabeculae and multivacuolated brown fat cells replacing the normal white fat and hematopoietic elements, diagnostic of intraosseous hibernoma.
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Mutations of isocitrate dehydrogenase-1 gene (IDH1), most commonly resulting in replacement of arginine at position 132 by histidine (R132H), have been described in World Health Organization grade II and III diffuse gliomas and secondary glioblastoma. Immunohistochemistry using a mouse monoclonal antibody has a high specificity and sensitivity for detecting IDH1 R132H mutant protein in sections from formalin-fixed, paraffin-embedded tissue. Angiocentric glioma (AG), a unique neoplasm with mixed phenotypic features of diffuse glioma and ependymoma, has recently been codified as a grade I neoplasm in the 2007 World Health Organization classification of central nervous system tumors. ⋯ All control cases showed appropriate reactivity. IDH1 R132H mutation has been described as a common molecular signature of grade II and III diffuse gliomas and secondary glioblastoma; however, AG, which exhibits some features of diffuse glioma, has not been evaluated. The absence of mutant IDH1 R132H protein expression in AG may help further distinguish this unique neoplasm from diffuse glioma.
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Tobacco and alcohol use are established risk factors for head and neck squamous cell carcinoma (HNSCC). However, patients with a unique subset of human papilloma virus (HPV)-associated HNSCC have been documented to have a better survival outcome. These tumors occur more frequently in the tonsils and oropharyngeal sites, among younger patients, higher socioeconomic group, and those exposed to more sexual partners and oral sex compared with HPV-negative HNSCC. ⋯ This study compares the p16 IHC staining patterns in HNSCC and laryngeal papillomas and assesses the concordance of p16 and high-risk HPV-ISH to determine the usefulness of p16 as a first-line marker. Using an objective criterion of diffuse intense confluent staining pattern as definite positive (akin to the 3+ of HER2/neu in breast cancer) and focal scattered staining pattern as equivocal reaction requiring confirmatory HPV assay, p16 IHC expression shows good concordance with high-risk HPV-ISH and can be used as a first-line marker. We propose p16 overexpression as a suitable surrogate and screening marker, with high potential of impacting the standard of care.