A 68 year old female presents with a relatively large, crusty scaly patch over the dorsum of her left hand. She describes the area as a persistent red patch that often itches. She has had significant sun exposure with multiple BCC and SCC excisions.

What is the most likely diagnosis?

Psoriatic plaque    
Bowen's disease     green tick
Basal cell carcinoma    
Squamous cell carcinoma    
Melanoma    

Well done, correct.