Case Reports

Xanthogranulomatous Osteomyelitis of Proximal Femur Masquerading as Benign Bone Tumor

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References

Discussion

To the best of our knowledge, a total of 5 cases of XO have been reported in the literature. The earliest of these reports were by Cozzutto and Carbone,1 who reported 2 cases of XO of the first rib and of the epiphysis of the tibia, respectively. The importance of these lesions to diagnosis is their confusion with a neoplastic disease, as XO is itself a benign disorder. These lesions can mimic a neoplastic lesion in clinical and radiologic presentation and the only way to differentiate the lesion from a neoplastic disease is by histopathologic examination of the tissue. Hypothetically, xanthogranulomatous disorders can be related to trauma or infection.

In 2007, Vankalakunti and colleagues6 reported XO of the ulna in a 50-year-old postmenopausal woman. In that case, progressive swelling was present on the extensor aspect of her right forearm for a period of 2 years, for which curettage and bone grafting were performed, using autograft from the ipsilateral iliac crest. The tissue culture was sterile, and XO was diagnosed as a result of the histopathologic examination. In 2009, Cennimo and colleagues7 reported XO of the index finger and wrist of a man complaining of pain and swelling for 1 year, which was unresponsive to antibiotics. The diagnosis of XO was confirmed histopathologically, when the culture of the same tissue grew Mycobacterium marinum. Radical synovectomy of the lesion was performed, after which minocycline, clarithromycin, and ethambutol were administered. In 2012, Borjian and colleagues8 reported a case of XO of the proximal humerus and proximal fibula in a 14-year-old child. The child, who presented with fever, pain, and restriction of shoulder movements, was started on oral antibiotics as the tissue culture grew Staphylococcus aureus; the patient did not complete the course of treatment in the hospital. No surgical intervention was done in this case. The diagnosis of XO was confirmed by microscopic examination of the tissue.

An association between bacterial infection and xanthogranulomatous inflammation has existed in several organs, such as the kidneys, and in the gastrointestinal system, but such an association of the 2 is yet to be determined for bone.5,10,16-19 Because of the paucity of literature on the disease, a management protocol for XO of bone has not been defined, and decisions have to be made considering the natural history of the disease in other organs. We present this case primarily because of its rarity, curability, and its close resemblance to bone tumors. While XO is benign, it can mimic a neoplastic bone lesion in its imaging and clinical manifestations, and appropriate differentiation is crucial. Currently, histopathologic examination of lesions is the most specific and is the gold standard for diagnosis.

Conclusion

Xanthogranulomatous osteomyelitis is a very rare entity, and only a few cases have been reported in the English-language literature. Though rare, XO warrants greater emphasis than it receives in the literature. It is a chronic inflammatory disease having a close resemblance to bone tumors. A high index of suspicion must be practiced to differentiate XO from tumors. Histopathologic examination is mandatory to establish definitive diagnosis and correct treatment.

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