A 17-year-old girl is brought to the office for evaluation of a right wrist mass. She noticed swelling on the top of her wrist approximately 3 months ago but said that it did not bother her until she was teased about it in school. She has no other concerns. Examination shows a nontender, rounded mass on the dorsal wrist that transilluminates with a penlight. An image of the mass is shown below: Which of the following is the most likely underlying etiology?

Question

A 17-year-old girl is brought to the office for evaluation of a right wrist mass.  She noticed swelling on the top of her wrist approximately 3 months ago but said that it did not bother her until she was teased about it in school.  She has no other concerns.  Examination shows a nontender, rounded mass on the dorsal wrist that transilluminates with a penlight.  An image of the mass is shown below:  Which of the following is the most likely underlying etiology?

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11ec160b_3b63_0884_9249_b97f1d56f907_MD0001_00 This patient has a ganglion cyst, a benign, fluid-filled mass that overlies a joint or tendon. Ganglion cysts occur most commonly on the dorsal wrist; other common sites include the volar wrist, digits, and feet. They are thought to be due to mucoid degeneration of periarticular tissue, leading to outpouching of the connective tissue. Mucinous fluid collects via a 1-way valve mechanism, possibly due to repetitive joint movements, resulting in slow growth of the cyst. Ganglion cysts are usually painless, and most patients seek medical attention because of cosmetic concerns or fear of malignancy. However, some patients may experience mild aching, and significant compression can occasionally result in paresthesia or weakness. Physical examination reveals a smooth, rubbery, round structure that overlies a joint or tendon and transilluminates with a penlight. Most ganglion cysts resolve spontaneously without intervention. (Choice A) Lipomas are benign neoplasms caused by the proliferation of fat cells. Although they can occur on the wrist, they most commonly present on the trunk or proximal arms. Lipomas do not transilluminate. (Choice C) Rheumatoid arthritis (RA) is characterized by immune-mediated joint destruction. It can be associated with rheumatoid nodules, which present as nontender subcutaneous nodules over pressure points (eg, olecranon process). However, rheumatoid nodules do not transilluminate, and patients with RA typically have symmetric joint swelling and pain in the small joints of the hands and wrists, as well as characteristic joint deformities (eg, ulnar deviation). (Choice D) Synovial sarcoma occurs from the malignant transformation of synovial tissue and can cause isolated swelling along the tendons. However, it does not transilluminate. (Choice E) Tophi occur from chronic uric acid deposition and present with firm, nontender subcutaneous nodules that are often yellow tinged; they do not transilluminate. In addition, patients usually have a history of recurrent gout flares (ie, exquisitely painful, swollen, erythematous joint). Educational objective: Ganglion cysts are benign, fluid-filled masses that occur due to mucoid degeneration of periarticular tissue. They present as painless, smooth, rubbery, round structures that overlie joints (eg, wrist) or tendons and transilluminate with a penlight. Most resolve spontaneously without intervention.

A 17-Year-Old Girl Is Brought to the Office for Evaluation