Recurrent acute limb swelling with mild D-dimer elevation leading to longitudinal recognition of characteristic imaging findings consistent with multisite calcium pyrophosphate deposition disease: a case report

Background Calcium pyrophosphate deposition (CPPD) disease is a crystal-associated arthropathy that may present with acute monoarticular inflammation and mimic thrombotic, traumatic, or degenerative conditions. Definitive diagnosis requires synovial fluid analysis; however, aspiration may not be feasible in the setting of minimal effusion. Imaging findings such as fibrocartilage chondrocalcinosis and peri-odontoid calcification may provide critical diagnostic clues. This case highlights the importance of longitudinal diagnostic reasoning and retrospective imaging synthesis when recurrent inflammatory episodes are initially evaluated as isolated events. Case presentation A Black woman in her late 60s was referred for outpatient musculoskeletal evaluation following a motor vehicle accident. During care she developed acute right knee swelling with calf tenderness, prompting evaluation for deep venous thrombosis and gout, including D-dimer and serum uric acid testing. Normal uric acid and mildly elevated D-dimer levels prompted referral for lower extremity duplex ultrasonography (US). Review of prior emergency department records revealed a similar episode of acute wrist swelling associated with mildly elevated D-dimer and negative duplex ultrasound imaging. Expanded retrospective imaging review demonstrated linear calcification of the triangular fibrocartilage complex, lamellar meniscal calcification at the knee, bilateral hip chondrocalcinosis, and peri-odontoid calcification consistent with a crowned dens configuration. Synovial fluid analysis was considered on two occasions but deferred because of minimal effusion. Integration of multisite fibrocartilage calcifications supported a working diagnosis of probable imaging-supported recurrent CPPD rather than thrombotic disease. Conclusions This case underscores the importance of cross-episode diagnostic integration of history and imaging in patients with recurrent inflammatory limb swelling and mild D-dimer elevation. Recognition of characteristic fibrocartilage and peri-odontoid calcification patterns may facilitate identification of probable CPPD when aspiration is not feasible and broaden the differential diagnosis in patients with recurrent inflammatory limb swelling.