This 44-year-old woman presented to her family physician with complaints of chronic unilateral wrist pain with intermittent redness and local heat, with no previous episode of wrist trauma or infection and no known malignancy. Serum WBC, calcium, urate and phosphate levels were normal. A left wrist radiograph was performed (Fig. 1).
The radiographs reveal a focus of dystrophic soft tissue calcification antero-medial to the carpal bones, near the pisiform. The most likely diagnosis in this young woman is:
a) triquetral avulsion injury
c) calcium pyrophosphate deposition disease (CPPD)
d) synovial sarcoma
e) hydroxyapatite deposition disease (HADD)
The answer is e) hydroxyapatite deposition disease (HADD)
The crystal deposition disorders are frequently encountered clinical diseases that lead to articular and periarticular pain. The most common and well known of these is gout, in which monosodium urate crystals are involved. The other common crystal deposition diseases are calcium pyrophosphate deposition disease (known as CPPD, or “pseudogout”), and calcium hydroxyapatite deposition disease (HADD). These disorders may involve one joint or many, may arise as primary abnormalities (most commonly) or may be associated with other disease entities such as hemophilia, hyperparathyroidism, hypervitaminosis D, hemochromatosis, hypophosphatasia, hypothyroidism, rheumatoid arthritis, renal failure, amyloidosis and ochronosis.
Calcium hydroxyapatite deposition disease is a very common idiopathic disorder characterized by the presence of various calcium crystals (mainly hydroxyapatite) in the periarticular soft tissues, particularly tendons, which may cause both acute and chronic arthritis and bursitis. HADD is likely best known as “calcific tendonitis” at its most frequent joint of involvement, the shoulder, afflicting the distal rotator cuff complex. HADD occurs in up to 3% of adults between the ages of 40 and 70 years and can result in joint pain, local swelling, erythema, and low-grade fever, along with potential bone erosion, adhesive capsulitis and even joint destruction. “Milwaukee shoulder” describes a clinical presentation of shoulder pain, periarticular and hyaline cartilage calcification, destructive inflammatory-type arthropathy and apatite crystals in the synovial joint fluid.
On plain x-rays, the features of HADD can vary from localized small amorphous clumps of dystrophic periarticular soft tissue calcification (most common), to more defined linear and coarse calcific deposits, with hyaline cartilage and meniscal calcification as well (chondrocalcinosis). The crystals can be demonstrated in synovial joint fluid by light microscopy (purple-staining clumps on Wright’s stain) and electron microscopy.
Treatment of HADD depends on the clinical presentation and severity of disease. In most patients, non-steroidal anti-inflammatory medications (NSAIDs), local heat and/or ice application and range-of-motion exercises will be all that’s required. Occasionally, periarticular or intra-articular steroid injections (methylprednisolone) may be needed. After a short course of conservative treatment (with or without steroids) the dystrophic calcifications may in fact resolve entirely on imaging studies, concomitant with resolution of clinical symptoms.
Although HADD is clinically similar to CPPD arthropathy (“pseudogout”) and gout, the hydroxyapatite crystals are distinctly different from the crystals of pseudogout or gout. The conditions, though, may co-exist, and hydroxyapatite crystals are not uncommonly found in the company of the calcium pyrophosphate crystals. CPPD is typically an intra-articular disease, not periarticular, as in the case shown. Although gout can result in localized soft tissue calcification as shown, the appearance is more typical of HADD. Triquetral avulsion injury refers to traumatic fracture involving the dorsal aspect of the triquetral bone of the proximal carpal row, at the attachment of the radiocarpal ligament. The fragment may be located in the same position on the AP radiograph, as the abnormality of the case presented, but is situated dorsal to the carpal bones on the lateral x-ray (vs the volar location in Fig. 1). As such, this is not a consideration in this case. Synovial sarcoma is a rare malignancy that typically develops in younger adults, usually before age 30, more common in men (2:1 ratio). One third of lesions contain dystrophic calcification but usually also exhibit other findings such as a prominent non-calcified mass lesion, and aggressive features like adjacent lytic cortical bone destruction and periosteal reaction. The diagnosis of HADD is much more likely than synovial sarcoma in the case presented.
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