Sheng-Kai Wang,1 Jia-Wei Cai,2 Yu Zhang,3 Ya-Jing Lin,4 Yi-Hui Yang2 

1Department of Pathology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang, 310022, People’s Republic of China; 2Department of Pathology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, 321000, People’s Republic of China; 3Department of Pathology, Hangzhou TCM Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, Zhejiang, People’s Republic of China; 4Department of Clinical Laboratory, the First People’s Hospital of Wenling, Affiliated to Wenzhou Medical University, Taizhou, Zhejiang Province, People’s Republic of China

Correspondence: Yi-Hui Yang, Department of Pathology, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, No. 365, Renmin East Road, Jinhua, 321000, People’s Republic of China, Tel/Fax +86 139 5848 5323, Email aoliao0211@163.com

Abstract: Squamous cell carcinoma (SCC) in situ can occur on any skin or mucus surface and is more commonly found in elderly patients on areas of skin that have been sunburnt. Most previous case reports are from dermatologists, with few published reports from pathologists. In this study, three patients underwent pathological routine and auxiliary immunohistochemical (IHC) examination and were ultimately diagnosed with pagetoid SCC in situ – a different diagnosis from the initial clinical assessment. All three patients received a complete resection of the skin mass. After follow-up, as of June 2023, the patients had no tumour recurrence or metastasis. Pagetoid SCC in situ is a particular type of SCC in situ that has no specific features in clinical manifestations, gross diagnosis or histopathological sections. The final diagnosis depends on IHC staining. Pagetoid SCC in situ expresses EMA, CK5/6 and p63 but not CEA, CK8 or S-100, which are expressed in extramammary Paget’s disease. Pagetoid SCC in situ is usually only locally invasive, and the main treatment is complete surgical resection. The prognosis is related to human papillomavirus infection, surgical margin closure, disease location, tumour thickness and other factors.

Keywords: pagetoid, pagetoid squamous cell carcinoma in situ