Erythema induratum and tuberculosis-associated ocular inflammation in low tuberculosis incidence setting: 11-year retrospective case review with prospective clinical follow-up in Alberta, Canada

Background: Erythema induratum (EI) – nodular vasculitis associated with Mycobacterium tuberculosis (TB) – and Tuberculosis-Associated Ocular Inflammation (TB-AOI) represent uncommon manifestations of TB in low incidence countries. Both entities are diagnosed indirectly and neither has standardized therapy.

Methods: Retrospective review of EI and TB-AOI cases managed in a provincial TB program between January 1, 2004, and December 31, 2014. Prospective phone-based follow-up pursued for those who received anti-tuberculosis therapy (ATT). TB-AOI diagnosis was based on referring ophthalmologist’s assessment and positive TB testing (IGRA/TST). EI cases were referred following dermatologist assessment and met clinical or pathologic criteria along with positive TB testing.

Results: 22 EI and 21 TB-AOI cases were managed over the study period, 10 and 11, respectively, were reached for phone-based follow-up. The majority of EI and TB-AOI cases were female and immigrated from TB high-burden countries. Mean ages at time of diagnosis were 44.3 and 39 years (IQR 8.25 & 18) for EI and TB-AOI cases, respectively. Mean duration of symptoms prior to diagnosis were 3.1 and 1.8 years (IQR 2 & 2.1) for EI and TB-AOI cases, respectively. Amongst 17 EI cases that underwent biopsy, granulomatous inflammation was the most common finding (88%) followed by panniculitis (59%), necrobiosis (53%) and vasculitis (47%). ATT was initiated in 41 (95%) cases with 36 (88%) completing therapy. 14 different ATT regimes were used for a mean duration of 5.8 months (Range 1-9). ATT related side effects occurred in 52% of EI and 35% of TB-AOI cases of which 18% and 19%, respectively, resulted in therapy cessation. Clinical resolution was documented in 70% of EI cases at a mean clinical follow-up of 7.3 months (Range 0-48); however, only 50% of EI and 18% of TB-AOI patients reported sustained resolution of symptoms on phone-based follow-up at mean post treatment periods of 4.5 and 3.8 years (IQR 3.8 & 4), respectively.

Conclusion: In this cohort, EI and TB-AOI represented uncommon presentations receiving highly variable therapy with high rates of ATT side effects. Fewer than half of patients contacted on follow-up reported durable resolution of symptoms.