Korean J Dermatol.  2020 Jan;58(1):14-19.

Interferon-gamma Release Assay Positivity in Korean Patients with Erythema Nodosum/Erythema Induratum

• Kim KS
• Kim SS
• Kim CW

Abstract

Background
Erythema nodosum (EN) and erythema induratum (EI) are similar inflammatory diseases of the lower extremities. Several factors (infections, drug hypersensitivity, inflammatory diseases, etc.) have been suggested as the cause of these diseases. Among them is Mycobacterium tuberculosis (MTB) infection. However, there is still a lack of evidence supporting this finding.
Objective
This study aimed to confirm whether Korean patients with EN/EI will exhibit positive interferon-gamma release assay (IGRA) results and determine the association of these disease with tuberculosis.
Methods
We retrospectively analyzed the clinical characteristics and IGRA test results of 62 patients (46 with EN and 16 with EI).
Results
A total of 22 of 44 EN patients (50%) had positive IGRA test results, except for two with “undetermined” results, and 12 of 16 EI patients (75%) had positive test results. This result was higher than that of the control group (15.5%, 292/1887) and showed a statistically significant difference (each p=0.000). Moreover, the proportion of EI patients with positive test results was higher than that of patients with severe psoriasis (35.6%, 112/315; p=0.001). Among EN/EI patients with positive IGRA test results, those treated with antituberculosis therapy (HREZ) showed good response rate. The response rate was 85.7% (6/7) for patients with EN and 90% (9/10) for those with EI.
Conclusion
High IGRA positivity was found in Korean EN/EI patients. This finding suggests a significant association between these diseases and tuberculosis.

Keyword

Erythema nodosum; Erythema induratum; IGRA; Tuberculosis