Nocardia brain abscess
Dr. Mark C. Delano
over 4 years ago
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Joseph Junewick, MD FACR
|Diagnostic Category: Developmental or Congenital
|Created: over 5 years ago
|Updated: over 5 years ago
Painful enlarging mass.
MR – Snail-shaped macrolobulated fluid collection continuous with the superior recess of the pisotriquetral joint and flexor ulnaris tendon.
Pain and tenderness are common in the palmar and ulnar aspects of the wrist in the area of the pisiform bone. When chronic, this pain may be due to tendinopathy at the insertion site of the ulnar flexor tendon, to carpal fractures, or to osteoarthritis of the pisotriquetral joint.
The most common soft-tissue masses in the hand and wrist are ganglion cysts although volar cysts are less common than dorsal cysts. Ganglion cysts may occur at any age but are most prevalent during the 2nd, 3rd, and 4th decades of life. Women are affected three times as often as are men. Ganglion cysts likely arise from modified synovial or mesenchymal cells at the synovial-capsular interface, in response to repetitive minor injury which stimulates the production of hyaluronic acid. The cyst wall consists mainly of collagen fibers and has no synovial lining. A small pedicle frequently connects a ganglion cyst of the hypothenar eminence with the pisotriquetral joint.
A synovial cyst in the hypothenar eminence is usually associated with pisotriquetral joint osteoarthritis or synovitis. The pisotriquetral joint is connected to the radiocarpal joint in most patients; it includes a large superior recess and a smaller inferior one. A ganglion cyst, in contrast, is often the only visible lesion, with no joint alteration.
Theumann NH, Pfirrmann CWA, Chung CB, et al. Pisotriquetral Joint: Assessment with MR Imaging and MR Arthrography. Radiology (2002); 222: 763-770.
Blum AG, Zabel JP, Kohlmann R, et al. Pathologic Conditions of the Hypothenar Eminence: Evaluation with Multidetector CT and MR Imaging. Radiographics (2006); 26:1021-1044.