Abnormal skin changes and unilateral vision loss after a tuberculin skin test

In Canada, latent tuberculosis (TB) is diagnosed with a positive tuberculin skin test (TST) or QuantiFERON-TB Gold Plus (QFT-Plus), in the absence of clinical symptoms. The TST or QFTPlus tests measure the immune response to M. tuberculosis antigens. In the TST, a small amount of purified protein de...

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Bibliographic Details
Published in:Canadian Medical Association journal (CMAJ) 2021-11, Vol.193 (47), p.E1811-E1814
Main Authors: Naidu, Sumana C, Kaplan, Alexander J, Daneman, Nick, Sundaram, Arun N E, Kohly, Radha P
Format: Article
Language:English
Subjects:
Antigens
Asymptomatic
Blindness
Blood tests
Canada
Case studies
Causes of
Complications and side effects
Cutaneous manifestations of general diseases
Diagnosis, Differential
Diagnostic tests
Drug Hypersensitivity - etiology
Drug Therapy, Combination
Edema
Female
Humans
Infections
Latent Tuberculosis - diagnosis
Latent Tuberculosis - drug therapy
Lymphatic system
Patients
Practice Cases
Risk factors
Steroids
Tuberculin test
Tuberculin Test - adverse effects
Tuberculosis
Uveitis - drug therapy
Uveitis - microbiology
Vaccines
Visual impairment
Young Adult
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Summary:In Canada, latent tuberculosis (TB) is diagnosed with a positive tuberculin skin test (TST) or QuantiFERON-TB Gold Plus (QFT-Plus), in the absence of clinical symptoms. The TST or QFTPlus tests measure the immune response to M. tuberculosis antigens. In the TST, a small amount of purified protein derivative of M. tuberculosis is injected intradermally, whereas the QFT-Plus is a blood test. With TST, in someone with latent TB, there is a delayed type IV hypersensitivity reaction that peaks within 2-3 days when the test is read, while the QFT-Plus can be completed in 24 hours. The TST has cross-reactivity in those who have received the Bacillus Calmette-Guérin vaccine; therefore, QFT-Plus is the preferred testing method for these patients. Neither test can differentiate between latent or active TB. Here, Naidu et al examine the case of a 20-year-old woman who had a florid TST reaction, a unilateral granulomatous panuveitis, a positive QFT-Plus, and a culture-positive mediastinal lymph node after the TST reaction, suggesting the presence of active TB.
ISSN:0820-3946
1488-2329
DOI:10.1503/CMAJ.211021