Calcium PyroPhosphate Deposition disease

Overview

Precipitation of crystals of calcium pyrophosphate dihydrate (CPP crystals) can be asymptomatic or associated with degenerative and/or inflammatory changes. The spectrum of CPPD disease (Calcium PyroPhosphate Deposition disease) consists of acute CPP crystal arthritis (closely resembling gout), chronic CPP crystal inflammatory arthritis (similar to rheumatoid arthritis), osteoarthritis with CPPD (similar to osteoarthritis), and other less frequent manifestations; more than one clinical phenotype is present in many patients. It is one of the most common forms of inflammatory arthritis, yet one of the least studied. Preferably, the diagnosis is based on the combination of clinical picture and detection of CPP crystals in the synovial fluid from affected joint. However, since accurate synovial fluid analysis is not always feasible in daily practice, X-ray imaging (or USG/CT) with a demonstration of chondrocalcinosis or soft-tissue calcification in the affected joint represents an alternative. If this does not enable establishing the diagnosis, X-rays of hands/wrists, pelvis, and knees can be added. The vast majority of patients suffer from an idiopathic form of CPPD disease, but the condition can develop on the background of an injury (trauma, surgery – meniscectomy, etc.), underlying genetic impairment, hyperparathyroidism, hemochromatosis, or hypomagnesaemia, and this should be considered in a younger individual (< 60 years of age). The therapeutic options consist of usual non-pharmacologic measures (rest, splinting, icing), joint aspiration and/or intra-articular steroid injection, analgesics, and, in particular, anti-inflammatory therapies. Unfortunately, the evidence base for individual treatment modalities is of a low quality, or absent. The widely recommended first-line options are NSAIDs, colchicine, and steroids, but none of them has been evaluated in a randomized controlled trial. The second-line options are hydroxychloroquine, methotrexate, magnesium carbonate, ACTH analogs, anakinra, tocilizumab, and radiation synovectomy. There is no modality that can eliminate the causative CPP crystals from the body.

Keywords:

calcium-pyrophosphate-dihydrate crystals – chondrocalcinosis – CPPD