RANKL expression is a useful marker for differentiation of pagetoid squamous cell carcinoma in situ from extramammary Paget disease

• Published in: Journal of cutaneous pathology 2016-09, Vol.43 (9), p.772-775
• Main Authors: Fujimura, Taku, Kambayashi, Yumi, Kakizaki, Aya, Furudate, Sadanori, Aiba, Setsuya
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Biomarkers, Tumor - analysis; Carcinoma in Situ - diagnosis; Carcinoma, Squamous Cell - diagnosis; Diagnosis, Differential; extramammary Paget disease; Female; Humans; Immunohistochemistry; Male; Middle Aged; Paget Disease, Extramammary - diagnosis; pagetoid squamous cell carcinoma in situ; PD-L1; RANK Ligand - analysis; RANK Ligand - biosynthesis; RANKL; Skin Neoplasms - diagnosis
• ISSN: 0303-6987; 1600-0560
• DOI: 10.1111/cup.12743

Background Pagetoid squamous cell carcinoma in situ (SCCIS) is a histopathologic variant of SCCIS composed of cells that display an abundant, pale‐staining cytoplasm in a pagetoid distribution within the epidermis. As pagetoid SCCIS is sometimes difficult to differentiate from extramammary Paget disease (EMPD) histopathologically, specific markers for pagetoid SCCIS or EMPD are needed by dermatopathologists. Methods In this report, we employed immunohistochemical staining for receptor of activated nuclear factor kappa ligand (RANKL) and programmed death‐ligand 1 (PD‐L1) in six cases each of pagetoid SCCIS and EMPD. Results The Paget cells strongly expressed RANKL in EMPD, whereas the atypical keratinocytes did not express RANKL in any of the six cases of pagetoid SCCIS. In all cases of pagetoid SCCIS, atypical keratinocytes expressed PD‐L1. In EMPD, Paget cells expressed PD‐L1 in half of the cases at a lower level of expression than was seen in the surrounding keratinocytes. Conclusion This study suggested that RANKL, but not PD‐L1, could be a marker to differentiate between pagetoid SCCIS and EMPD.