Acute Calcific Tendinitis of Flexor Carpi Ulnaris: A Big Mimicker and Unusual Cause of Wrist Pain with a Pictorial Review

: Calcific tendinitis of flexor carpi ulnaris (FCU) at the wrist is an extremely rare cause of ulnar side pain of the wrist. Owing to the infrequency of this entity, most cases are misdiagnosed as other diseases such as fractures, tendinopathies or infection. We present a case of recent-onset ulnar side wrist pain and swelling with a normal radiography. This case was referred to the imaging clinic to obtain magnetic resonance imaging (MRI) to rule out Kienbock disease. Multimodality imaging examination confirmed the correct diagnosis of acute calcific tendinitis. After two weeks of rest, wrist immobilization by splinting and consumption of anti-inflammatories, the patient’s symptoms were resolved. To conclude, this case emphasizes the requirement of awareness about this uncommon but important cause of acute wrist pain and the need of applying imaging methods for an early and accurate diagnosis in order to avoid misdiagnosis and unwarranted treatments.