This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
Pencil-in-cup deformity is seen in 
Select and explain. 
A. Rheumatoid Arthritis, B. Psoriatic Arthritis, C. Ankylosing spondylitis, D. Gouty Arthritis
B: Psoriatic Arthritis
Answer: B: Psoriatic Arthritis 
Explanation: (B) Psoriatic Arthritis # Psoriatic Arthritis (PsA): The peripheral and axial arthropathies in PsA show a number of radiographic features that distinguish them from RA & AS, respectively.> Characteristics of peripheral PsA include DIP involvement, including the classic "pencil-in-cup" deformity; marginal erosions with adjacent bony proliferation ("whiskering"); small joint ankylosis; osteolysis of phalangeal and metacarpal bone, with telescoping of digits; and periostitis and proliferative new bone at sites of enthesitis> Characteristics of axial PsA include asymmetric sacroiliitis