This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Tophus is the pathognomic lesion of which of the following condition - 
Select and explain. 
A. Multiple myeloma, B. Cystinosis, C. Gout, D. Eale's disease
C: Gout
Answer: C: Gout 
Explanation: Gout

Gout is the common endpoint of a group of disorders that produce hyperuricemia.
It is marked by transient attacks of acute arthritis initiated by crystallization of monosodium urate into the joints, leading eventually to chronic gouty arthritis and deposition of masses of urates in joints and other sites, creating top
Most common joint involved in gout is a big toe, i.e. metatarsophalangeal joint of the great toe.