[Various manifestations of calcium pyrophosphate-associated arthritis].

In calcium pyrophosphate (CPP)-associated arthritis, deposits of calcium pyrophosphate lead to acute attacks of painful joint inflammation. The disease may present with signs of systemic inflammation such as fever, mimicking an infectious disease. Early recognition and treatment of this disease can prevent overdiagnosis and joint damage.

[Unexplained pain in the ankle and foot. Consider transient osteoporosis].

Transient osteoporosis is an increasingly recognized condition that causes severe pain in weight-bearing joints and is characterized by otherwise unexplained bone-marrow oedema on MRI. We present two patients, a 40-year-old man and a 60-year-old woman, with longstanding severe pain in the foot and ankle. Both had invalidating pain with only mild swelling of the foot or ankle.

[A man with swollen fingers].

A 28-year-old man was referred to our hospital because of localised swelling of his fingers, with suspicion of arthritis of the proximal interphalangeal (PIP) joints. At physical examination we observed a swelling, superficial to the PIP joints. Ultrasonography revealed a hypo-echoic structure above the extensor tendon, typical for knuckle pads.

Pain at the knee: the Morel-Lavallée lesion, a case series.

Post-traumatic pain at the knee is a common clinical presentation with a wide and varied differential diagnosis. The Morel-Lavallée lesion (MLL) is a rare cause of pain at the knee, caused by post-traumatic shearing of the hypodermis from the underlying fascia. The space created can fill with blood, lymph and necrotic fat giving specific findings on ultrasound and magnetic resonance (MR) evaluation.