A case of systemic lupus erythematosus presenting as bilateral avascular necrosis of femur

A 26 year old female has been referred to our clinic with right sided hip pain of sub acute onset. Her pain worsened with movement and weight bearing. On clinical examination, she had restricted range of movement with pain and mild joint tenderness. On plain x-ray she found to have AVN of right femoral head suggested by classical crescent sign with preserved articular margins on plain film and underwent extensive evaluation for a cause. Apart from malaise, fatiguability and moderately elevated erythrocyte sedimentation rate (ESR) of 65 mm in 1st h no other symptom or laboratory feature could be found. Her hemoglobin level was 10.6 g/dL and white cell count, platelet count, C-reactive protein was normal. After 6 months she presented with a similar pain in left hip and subsequent work up revealed AVN of left femoral head as well on plain x-ray and findings were similar to the previous right sided hip joint. Other than above presentation she had no other complains at that point. Her past medical history was not significant, she gave birth to a healthy term baby 7 months prior to above presentations and her obstetric history was uneventful. She did not consume alcohol and was a non-smoker. She was not on any form of corticosteroid or other medications prior to the event except nutritional supplements during antenatal period and she has not taken any indigenous medicines. There was no family history of connective tissue or other autoimmune condition of note. At the time she of the second event of hip pain she underwent a comprehensive work up with involvement of a multidisciplinary specialists. In view of persistently high ESR and multiple AVN of bones, she underwent a work up for chronic infections such as tuberculosis, and for autoimmune connective tissue diseases with serological studies including antinuclear antibody (ANA), Anti Smith antibody (Sm), serum complements C3 and C4, Anti Ro and Anti La antibodies. She was also screen for Human Immunodeficiency Virus (HIV) infection, Hepatitis B and C infections. Hematological evaluation for sickle cell disease, thrombophilic conditions including anti-cardiolipin antibodies IgG and lupus anticoagulant test, beta-2 glycoprotein 1 both IgM and IgG. All of the above tests were negative. A probable cause could not be ascertained despite above extensive workup. She has been continuously followed up with a future plan of hip joint replacement. During the subsequent period patient revealed that she felt mild fatiguability and hair loss continuously, which she considered not significant and did not report to the doctor hence further workup was not done for next 4 years. She did not take any medications except simple paracetamol for hip pains. After about 4 years of above events she reported significant hair loss, which was unusually high according to her. On further assessment she found to have isolated thrombocytopenia of less than 100,000/mm³ on repeated blood counts and also continuously high ESR, at times exceeding 100 mm/1st h. Patient was re-evaluated considering above developments. She had positive ANA with titre above 1:160 and a positive anti double stranded DNA (dsDNA) antibody with titre of 233 IU/mL. Both these tests were negative 3 years back. She did not report abnormality in urinalysis or neuropsychiatric manifestations of SLE. In light of above clinical manifestations and serological studies, definite diagnosis of SLE was made according to SLICC 2012 classification criteria. Her coagulation screening was repeated and was negative although beta-2 glycoprotein 1 was not repeated. Her initial presentation of bilateral AVN of femoral head 4 years back was ascertained as related to evolving autoimmune disease, since no other etiology was evidenced. Patient was prescribed hydroxy-chloroquine and simple analgesics in her subsequent management and total hip joints replacement surgery was planned.