Soft-Tissue Swelling Around the Proximal Interphalangeal Joints Bilaterally—Quiz Case

A 16-year-old boy presented with asymptomatic progressive symmetrical thickening of the soft tissue around the proximal interphalangeal (PIP) joints of both hands of 2 years' duration. His medical history was remarkable for attention-deficit/hyperactivity disorder, for which he was prescribed methylphenidate hydrochloride. For the past 2 to 3 years, he and his psy-chiatrist had noted the development of a nervous tic consisting of stretching out the arms, grasping his fingers tightly across the PIP joints, and pushing externally. There was no other notable medical history, and his development was otherwise normal. No family members were similarly affected.

Physical examination revealed symmetric soft-tissue swelling of the second through fifth fingers at the location of the PIP joint bilaterally (Figure 1). Healing abrasions from prior accidental trauma were evident on the distal third and fourth digits. There were no joint effusions, and the range of motion across all joints was normal. Findings from radiographs of the hands were normal, aside from the evident soft-tissue swelling overlying all PIP joints. A skin biopsy specimen was taken from an involved site and histopathologically analyzed (Figure 2 and Figure 3).