Useful cytological confirmation of HPV 13 in lesional mucosa enhances diagnosis of focal epithelial hyperplasia

Abstract

An 11-year-old female presented with multiple oral lesions for several months. Histopathological findings suggested focal epithelial hyperplasia (FEH), also known as Heck disease. FEH is strongly associated with Human papillomavirus (HPV), especially genotypes 13 and 32. An oral swab of a mucosal lesion was subsequently obtained for cytology, immunohistochemistry and in situ hybridization. In addition, in situ hybridization and immunohistochemistry were also performed retrospectively on the biopsy specimen for correlation. The cytology specimen showed squamous cells with enlarged, slightly atypical nuclei and rare perinuclear halos. The histology findings included papillomatosis with acanthosis, mild nuclear atypia and focal perinuclear halos. The immunohistochemistry for the consensus HPV L1 capsid protein was found in both the cytology and biopsy specimens indicating that the lesion was HPV-related. High viral copy numbers of HPV 13 were detected by in situ hybridization in both the cytology and histology specimens. Although histologic features of FEH have been well characterized in the literature, to our knowledge, this is the first case to describe in FEH with adjunct immunohistochemistry and in situ hybridization results. Furthermore, these findings assisted in our diagnosis since the patient's clinical presentation was a diagnostic challenge with smooth dome-shaped papules instead of the typically described flat-topped verrucous lesions seen in FEH. In summary, our case reveals that there is a high concordance between the HPV 13 detection in the cytology and histology of FEH, and that performing cytology in addition to histology can be used to optimize diagnostic evaluation towards appropriate patient care.