Atypical Bilateral Cystic Foot Swellings with Osteomyelitis-Like Features: A Diagnostic Dilemma

Introduction: We report an unusual case of bilateral multiloculated cystic foot swellings in which extensive investigations failed to establish a definitive diagnosis, highlighting the challenges in distinguishing culture-negative infectious osteomyelitis from chronic non-infective osteomyelitis. Chronic osteomyelitis typically presents with localized infection and an identifiable microbiological etiology. However, atypical presentations with bilateral involvement and sterile cultures pose significant diagnostic challenges, especially in immunocompromised individuals. Case Report: A 56-year-old female presented with multiple bilateral foot swellings of 2 years duration, associated with pain. Clinical examination revealed well-defined cystic, fluctuant swellings without classical signs of infection. Magnetic resonance imaging (MRI) demonstrated multiloculated fluid collections with sinus tracts and adjacent bony involvement suggestive of chronic osteomyelitis. Despite aspiration and biopsy, microbiological studies remained negative. Histopathology revealed acute on chronic inflammatory granulation tissue. The patient had significant comorbidities, including diabetes mellitus, rheumatoid arthritis, and prolonged steroid use. Conclusion: Although MRI findings were highly suggestive of chronic osteomyelitis, persistently negative microbiological studies and non-specific histopathology precluded definitive confirmation of infection. After extensive multidisciplinary evaluation, chronic non-infective osteomyelitis emerged as the most plausible diagnosis. This case represents a significant diagnostic dilemma.