An 80–year–old man was admitted for low back pain and bilateral lower extremity weakness and gait instability for 6 months. He also had weight loss of 40 pounds and fatigue over the last 6 months. No fever or night sweats. Three years earlier, he was diagnosed with bladder cancer and had cystoscopic tumor removal followed by BCG therapy. Later he had surveillance cystoscopy three monthly without any evidence of recurrence. His past medical history includes HTN, SVT. On exam, pt was lethargic and had severe lower extremity weakness. Labs showed Sed rate 81, CRP 11.73, platelets 67,000 and Hb 9.4. MRI spine showed T10 mass with cord compression and CT scan of chest, abdomen and pelvis was normal. PET scan showed increased uptake at T10. Pt was diagnosed as having spinal mets given his prior history of bladder cancer. CT guided biopsy was attempted but failed. He received ten radiation treatments to the T10 area for presumed spinal metastasis. As he did not improve, he underwent T9–T10 thoracic laminectomy and decompression. The tissue pathology of T10 vertebral body showed no evidence of malignancy. Post surgery, he had some improvement and was transferred to LTAC. Three weeks later tissue culture from T10 was positive for Mycobacterium bovis. Hence he was diagnosed with M. bovis BCG osteomyelitis 32 months after the last BCG therapy. His CXR, T spot and HIV were negative. He was started on Isoniazid, Ethambutol and Rifampin. With treatment he continues to improve.
Only eleven cases of M. bovis Bacillus Calmette–Guérin (BCG) strain osteomyelitis secondary to intravesical therapy have been reported so far. BCG is used for treatment of transitional cell carcinoma of the urinary bladder. Complications of BCG include cystitis, hematuria and fever. Late organ–specific manifestations (pneumonitis, osteomyelitis etc) are due to a reactivation of BCG infection. BCG organisms persist for months after completion of therapy and may account for prolonged immune anticancer effect and also delayed disseminated infection for months and years after treatment. 6 out of 11 patients with BCG vertebral osteomyelitis required surgical intervention with debridement similar to our case. One patient received a presumptive diagnosis of metastatic lung cancer and underwent empiric radiation therapy similar to our case. BCG is clinically indistinguishable from M. tuberculosis but has worse prognosis. Differentiation of BCG from M. tuberculosis includes colony morphology, biochemical assays, susceptibility and PCR genomic analysis. Genetic resistance of BCG to pyrazinamide precludes its use. The regimen consists of Isoniazid, Rifampin and Ethambutol for the first 2 months, followed by Isoniazid and Rifampin for 7 months and for meningitis up to a total of 12 months.
M. bovis osteomyelitis is a rare complication of intravasical BCG therapy and timely tissue diagnosis is critical to avoid complications/surgery as it can mimic metastasis from bladder cancer.