Talk to Dermatologist on Lump/swelling?

He has had a swelling for 4 years on sole of left foot and palm of right hand. They were soft in consistency until a doctor diagnosed it as wart after treatment, it has become hard now and there was an increase in the size (2 x 2 cm now). Pain on and off. No itching. No discharge. Colorless from surface.

He is diabetic, hypertensive, psoriasis (biopsy pending).

Family history: eczema and non-Hodgkin's lymphoma.

He has an appointment with a dermatologist next week. Question is which other doctor should we visit and tests required for differentials? Will biopsy be required?