Immunohistochemical evaluation of p16 expression in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions

• Published in: Journal of cutaneous pathology 2016-08, Vol.43 (8), p.671-678
• Main Authors: Smith, Emily H., Lowe, Lori, Harms, Paul W., Fullen, Douglas R., Chan, May P.
• Format: Article
• Language: English
• Subjects: Biomarkers, Tumor - analysis; Cyclin-Dependent Kinase Inhibitor p18 - analysis; Cyclin-Dependent Kinase Inhibitor p18 - biosynthesis; Female; histiocytosis; Humans; Immunohistochemistry; melanocytic lesions; non-Langerhans cell; p16 protein; Skin Neoplasms - diagnosis; Young Adult
• ISSN: 0303-6987; 1600-0560
• DOI: 10.1111/cup.12730

Background Expression of p16 is frequently evaluated in melanocytic lesions. Expression of p16 in cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions has not been well characterized. Methods We evaluated p16 expression in a cohort of histiocytic (reticulohistiocytoma, Langerhans cell histiocytosis, xanthogranuloma, Rosai Dorfman disease and xanthoma), fibrohistiocytic (dermatofibroma, epithelioid fibrous histiocytoma and dermatofibrosarcoma protuberans) and undifferentiated (atypical fibroxanthoma and pleomorphic undifferentiated sarcoma) lesions. A group of melanocytic lesions (Spitz nevus, ordinary nevus, spitzoid melanoma and non‐spitzoid melanoma) were also evaluated as reference. Each case was scored by the proportion of p16‐positive cells and by staining intensity. Results Immunoreactivity for p16 was found in almost all histiocytic (28/30, 93%) and fibrohistiocytic (22/24, 92%) lesions. About half of the undifferentiated lesions also exhibited p16 staining (9/17, 53%). Most of the melanocytic cases examined in this study expressed p16. A wide range of staining intensity and proportion of p16‐positive cells was observed in most groups. Conclusion Expression of p16 is common, albeit variable in proportion and intensity, amongst a wide variety of cutaneous histiocytic, fibrohistiocytic and undifferentiated lesions. Further studies are required to determine if p16 expression is useful in distinguishing benign from malignant neoplasms of these types.