Although at first believed to be specific for actinic keratosis and squamous cell carcinoma, rosettes are sometimes seen in other lesions as well as in normal skin. Rosettes are most commonly found in:
Actinic keratosis (AK)
Thin squamous cell carcinoma (SCC)
Sun damaged skin
Tumours such as basal cell carcinoma (BCC) and melanoma
What is the histological explanation of rosettes?
The exact histological explanation of rosettes is unclear but they are thought to be due to an interaction between polarised light and narrowed keratin-filled, or fibroticadnexal openings.Haspeslagh et al found that small rosettes (0.1–0.2 mm) corresponded to concentric horny material in follicular and eccrine ducts at the infundibular level and larger rosettes (0.3–0.5 mm) to perifollicular concentric fibrosis .
Haspeslagh M, Noë M, De Wispelaere I et al. Rosettes and other white shiny structures in polarized dermoscopy: histological correlate and optical explanation. J Eur Acad Dermatol Venereol. 2016 Feb;30(2):311-3. doi: 10.1111/jdv.13080. Epub 2015 Mar 19. Review. PubMed PMID: 25786770.