|IMAGES IN RHEUMATOLOGY
|Year : 2016 | Volume
| Issue : 3 | Page : 171-173
Skeletal fluorosis mimicking seronegative arthritis
Department of Immunology and Rheumatology, Narayana Multispeciality Hospital, Ahmedabad, Gujarat, India
|Date of Web Publication||11-Aug-2016|
B-4 Shree Hari Krishna Park, Near Cadila Crossing, Ghodasar, Ahmedabad - 380 050, Gujarat
Source of Support: None, Conflict of Interest: None
Keywords: Arthritis, dental fluorosis, skeletal fluorosis
|How to cite this article:|
Shukla A. Skeletal fluorosis mimicking seronegative arthritis. Indian J Rheumatol 2016;11:171-3
Skeletal fluorosis is endemic in many districts of India including southern districts of Rajasthan.  A 44-year-old female with joint pains was referred from Dhansa village in Jalore district of Rajasthan. Her complaints were pain in shoulders, knees, and heel region for 6 months. She had generalized body ache with early morning stiffness in shoulder girdles for 60 min. On examination, she had tender shoulders, peripatellar enthesitis, and Achilles tendinitis More Details. There was no swelling of any joint. Investigations showed raised acute phase reactants with erythrocyte sedimentation rate of 26 mm at 1 h and serum C-reactive protein of 1.36 mg/dl. Serum rheumatoid factor and anti-cyclic citrullinated peptide tests were negative. Based on these findings, a provisional diagnosis of seronegative arthritis was thought. Examination of the teeth showed certain changes in the enamel with attrition of the teeth [Figure 1]. X-ray images of the forearm, lumbosacral spine, and pelvis showed interosseous membrane calcification, osteosclerosis of cortical bones, with prominent granular trabeculae. Sacroiliac joints were normal and no calcification of ligaments or membranes was seen in the axial skeleton [Figure 2], [Figure 3], [Figure 4]. Based on these findings, the diagnosis of skeletal fluorosis that mimicked seronegative spondyloarthritis was concluded. Urine and serum fluoride levels were not measured. The level of fluoride in ground water in these districts has been reported to be high, 1-4 ppm.  She lived in the region from the birth and used well water for drinking. Thus, the source of excess fluoride intake was ground water.
|Figure 1: Teeth showed lacy opaque white patches in enamel (arrows) along with brown mottling (block arrows). Few teeth had cracking and fissuring on the edges (empty arrows)|
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|Figure 2: Forearm anteroposterior X-ray image showing calcification of interosseous membranes (arrows), osteosclerosis suggested by thick and dense cortical bones in diaphysis (block arrows) and coarse prominent trabeculae forming a mesh-like pattern in metaphysis (empty arrows). The granular and prominent trabecular pattern is possibly due to fluoride deposits|
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|Figure 3: X-ray of the lateral view of lumbosacral vertebral spine showing increased bone density of vertebral bodies particularly on upper and lower edges with beaked pointed osteophytes (arrows)|
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|Figure 4: X-ray of the pelvis anteroposterior view showing osteosclerosis with normal sacroiliac joints and coarse prominent trabeculae forming a mesh-like pattern possibly due to fluoride deposits in the femoral bone (arrows)|
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The early symptoms of skeletal fluorosis are arthralgia and backache due to bone pain. Achilles tendinitis, early morning stiffness, and mild increase in acute phase reactants have also been reported.  These findings can mislead to a diagnosis of inflammatory arthritis. However, definite signs of synovitis, for example, joint effusion and synovial hypertrophy are not seen in these patients. It mimics seronegative spondyloarthritis more closely due to backache and enthesitis but can also manifest as seronegative symmetric polyarthralgia, thus mimicking rheumatoid arthritis. The United States Public Health Service has divided skeletal fluorosis based on symptoms and radiology into 4 phases [Table 1].  The present case had clinical phase-II skeletal fluorosis which closely mimics arthritis. Osteosclerosis alone is a nonspecific finding also seen in Paget's disease, metastasis, myelofibrosis, hemoglobinopathies, renal osteodystrophy, and congenital disorders including osteopetrosis. Soft-tissue calcification is also not diagnostic alone as it can be seen in ankylosing spondylitis, diffuse idiopathic skeletal hyperostosis, psoriasis, other spondyloarthropathies, alkaptonuria, hyperparathyroidism, hypophosphatemic rickets, and osteoarthritis. It is the combination of symptoms in a patient from endemic areas with above radiographic findings that clinch the diagnosis. In such cases, raised urine fluoride level is not necessary to confirm the diagnosis.
In addition to musculoskeletal, teeth examination helps in the diagnosis. Dental fluorosis results from exposure to high fluoride intake in childhood (<12 years age), a period of permanent teeth mineralization.  Dental fluorosis classification based on Dean's fluorosis index grades it into five categories as Grade 0: Normal, translucent, smooth and glossy teeth; Grade 1: White opacities, faint yellow line; Grade 2: Brown stain; Grade 3: Pitting and chipped off edges; and Grade 4: Brown plaques, corrosion and falling of teeth.  Awareness of the above clinical, radiographic, and dental findings can help physicians and rheumatologist from the endemic areas to make early and accurate diagnosis of fluorosis thus, preventing unnecessary workup and treatment for inflammatory polyarthritis and stress for these patients.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]