Histologically, both carcinomas were squamous cell carcinomas, therefore the incidence of the FGFR3 mutation among the squamous cell carcinoma cases was calculated as 3.2% (2/63).
In addition, within the BRAF inhibitor-associated group, the lesions designated as KAs and BRAF inhibitor-associated verrucous keratoses had a similar mutational profile (mutations in PIK3CA, APC, and HRAS), which was distinct to that seen in squamous cell carcinomas (FGFR3, CDKN2A, and STK11).
The lung cancer subtypes share some genetic variations such as the dysfunction of tumor suppressor gene TP53, and also harbor specific variations of their own such as MET in ADC, FGFR1 and FGFR3 in SCC and MYC in SCLC.
In contrast, the tyrosine kinase receptor FGF receptor-3 (FGFR3) and the transcription factor forkhead box N1 (FOXN1) were highly expressed in SKs, and close to undetectable in SCCs.
We investigated the activation of FGFR3 and OIS by mutation and immunohistochemical analysis in skin tumours, including seborrhoeic keratosis, actinic keratosis (AK), Bowen's disease (BD), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC).
The FGFR3 gene was gained in 0.6% (1/179) of oral squamous cell carcinoma but no amplification was found in oral and oropharyngeal squamous cell carcinoma.