Diffuse p16 Immunohistochemical Expression in Basaloid 'Human Papillomavirus-Like' Oral Epithelial Lesions May Not Be Human Papillomavirus-Associated.

Autor: Maghrabi, Dr. Amr El, Novack, Dr. Rachel, Gardner, Dr. Pamela J., Taleghani, Dr. Maryam, Ng, Dr. Tony L., Choi, Dr. Jason, Babul, Dr. Adam, Todorovic, Dr. Jason, Poh, Prof. Catherine F., Ko, Dr. Yen Chen Kevin
Zdroj: Oral Surgery, Oral Medicine, Oral Pathology & Oral Radiology; Aug2024, Vol. 138 Issue 2, pe54-e55, 2p
Abstrakt: Human papillomavirus (HPV)-associated oral epithelial dysplasia (OED) and squamous cell carcinoma of the oral cavity (OSCC) are uncommon. They are known to present with distinct histomorphology and diffuse block-like p16 immunohistochemistry (IHC). We recently described a novel OED classification system using p53 and p16 IHC and encountered several cases of OED with both diffuse p16 expression and aberrant p53 expression ("double-positive"). We hereby report five cases of "double-positive" p53 and p16 OED and OSCC with their unique morphology and results of high-risk (HR) HPV in situ hybridization (ISH) and TP53 mutation analysis. Five cases of "double-positive" OED and/or OSCC with basaloid morphology were identified from the British Columbia Oral Biopsy Service, Vancouver General Hospital and Pathology and Laboratory Medicine, Foothills Medical Centre, University of Calgary. HR HPV ISH was performed on all cases. TP53mutation analysis by targeted Next-Generation Sequencing (NGS) was performed on four of the five cases. All five cases showed abundant karyorrhectic cells, apoptotic keratinocytes, and basaloid or "Bowenoid" morphology. All five cases demonstrated p16 diffuse block-like positivity and p53 abnormal staining patterns (3 overexpression, 2 null). HR HPV RNA ISH was negative in all five cases. Three of the four cases sent for targeted NGS demonstrated pathogenic TP53 mutations. Our results suggest these "double-positive" cases should be classified as p53 abnormal-OED and p53 abnormal-OSCC, instead of HPV-associated OED and HPV-associated OSCC, to accurately reflect their underlying pathophysiology. Interpretation of p16 IHC in OED and OSCC with basaloid histomorphology should be done with extreme caution. Confirmation with p53 IHC, with consideration for HR HPV ISH is highly recommended to prevent misdiagnosis and misclassification of these oral lesions. [ABSTRACT FROM AUTHOR]
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