Spina ventosa: An often missed diagnosis

Rare and varied presentations of tuberculosis make it difficult for treating clinicians to arrive at the diagnosis. An adolescent female presented to the orthopedic outpatient department with slowly increasing swelling over the dorsum of the hand near the base of the third digit for 5 months. With multiple consultations, she was being treated with antibiotics as a case of abscess. On examination, the swelling was soft bulging with whitish watery discharge. Plain radiography revealed periosteal elevation with bony destruction of the proximal phalanx. Magnetic resonance imaging revealed signal intensity changes with collection suggestive of infection. Blood investigations were within the normal limits, except slightly raised erythrocyte sedimentation rate. A differential diagnosis of chronic osteomyelitis was performed. Since the swelling was growing with the overlying skin likely to give way, it was treated with incision and drainage. Cytology with Gram's and auramine staining helped in confirming the diagnosis of spina ventosa. Biopsy is the gold standard for diagnosis, and antitubercular therapy forms the mainstay of treatment.