A 68-year-old man comes to the office with a 2-day history of right foot pain and swelling. The pain started acutely when he awoke in the morning. Initially, the patient had pain only on dorsiflexion of the foot, but he progressively developed pain with any movement at the ankle or weight bearing. The patient has not had similar symptoms before. He is normally very active, and had spent a week bicycling in Utah 3 weeks prior to this presentation. Medical history is notable for type 2 diabetes mellitus, hypertension, and hyperlipidemia. Temperature is 37 C (98.6 F), blood pressure is 140/90 mm Hg, and pulse is 90/min. Examination of the right foot shows warmth, swelling, and tenderness over the dorsal surface of the foot and around the right ankle. Both dorsiflexion and plantar flexion are restricted due to pain. The skin is intact without ulcers or breaks. Pulses are full and equal in both feet, and sensory sensations are normal. X-rays reveal soft tissue swelling, small tibiotalar joint effusion, and chronic calcification of the articular cartilage. There are no fractures or dislocation. Which of the following is the most likely diagnosis?

Question

A 68-year-old man comes to the office with a 2-day history of right foot pain and swelling.  The pain started acutely when he awoke in the morning.  Initially, the patient had pain only on dorsiflexion of the foot, but he progressively developed pain with any movement at the ankle or weight bearing.  The patient has not had similar symptoms before.  He is normally very active, and had spent a week bicycling in Utah 3 weeks prior to this presentation.  Medical history is notable for type 2 diabetes mellitus, hypertension, and hyperlipidemia.  Temperature is 37 C (98.6 F), blood pressure is 140/90 mm Hg, and pulse is 90/min.  Examination of the right foot shows warmth, swelling, and tenderness over the dorsal surface of the foot and around the right ankle.  Both dorsiflexion and plantar flexion are restricted due to pain.  The skin is intact without ulcers or breaks.  Pulses are full and equal in both feet, and sensory sensations are normal.  X-rays reveal soft tissue swelling, small tibiotalar joint effusion, and chronic calcification of the articular cartilage.  There are no fractures or dislocation.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d517_8cc9_bc81_4908dafec22c_MD0003_00 This patient has characteristic findings of acute calcium pyrophosphate dihydrate (CPPD) crystal arthritis (pseudogout), including onset at age >65, monoarticular arthritis, and chondrocalcinosis (calcification of articular cartilage). Synovial CPPD deposition can also cause a chronic inflammatory arthritis resembling rheumatoid arthritis and a noninflammatory degenerative process resembling osteoarthritis. Pseudogout commonly affects the knees and ankles, where it may be difficult to distinguish from urate gout, but it also frequently affects the large joints of the upper extremity and may involve multiple joints concurrently. Attacks of pseudogout often occur in the setting of trauma/overuse, surgery, or medical illness. The finding of chondrocalcinosis in a joint with a typical acute inflammatory arthritis establishes a diagnosis of probable CPPD crystal arthritis. Synovial fluid analysis will show an inflammatory effusion (15,000-30,000 cells/mm³) along with rhomboid-shaped, weakly positively birefringent CPPD crystals. Arthrocentesis for synovial fluid analysis is advised to exclude urate gout (up to 50,000 cells/mm³, needle-shaped negatively birefringent urate crystals) and septic arthritis (>50,000 cells/mm³, visible organisms on Gram stain). chondrocalcinosis CPPD crystals (Choice A) The risk for septic arthritis is higher in joints injured by other conditions, including gout and pseudogout. However, septic arthritis is usually associated with fever and other systemic symptoms, and arises from hematogenous spread or following trauma. Chondrocalcinosis on x-ray is more suggestive of pseudogout. (Choice C) Urate gout has significant overlap with pseudogout in clinical features and may also affect the ankle. However, urate gout is not associated with chondrocalcinosis. (Choice D) Neuropathic (Charcot) arthropathy causes destructive arthritis in patients with long-standing diabetes who have peripheral neuropathy. Although the ankle is commonly involved, obvious deformities and chronic pain are characteristic. (Choice E) Plantar fasciitis causes subacute to chronic pain on the plantar surface of the hindfoot. Inflammatory features are absent, and the tibiotalar joint is not involved. (Choice F) Metatarsal stress fractures can be seen following strenuous activity and may be undetectable on initial x-ray. However, they are usually not associated with a joint effusion or chondrocalcinosis. Educational objective: The finding of chondrocalcinosis in a joint with a typical acute inflammatory arthritis establishes a diagnosis of probable calcium pyrophosphate dihydrate (CPPD) crystal arthritis (pseudogout). Synovial fluid analysis will show an inflammatory effusion and rhomboid-shaped, weakly positively birefringent CPPD crystals. References: Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases. (http://www.ncbi.nlm.nih.gov/pubmed/24703344)

A 68-Year-Old Man Comes to the Office with a 2-Day