pencil-in-cup signA term of art referring to bony erosions in which the narrowed end of a metacarpal or phalange rests in the expanded end of the adjacent bone sharing the joint. The pencil-in-cup sign is classically described in atrophic neuropathic arthropathy of severe psoriasis, as well as in rheumatoid arthropathy.
Plain films of involved joints show a tapering of the convexity and an exaggeration of the concavity of bones in the joint, and are accompanied by osteoporosis.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.