Is presence of ANCA positivity in pulmonary tuberculous patient an indication for concomitant steroid therapy?
Dear Ashraf,
Your question can be interpreted in a couple of different ways. But before I do that, I would like to mention a bit about the pretest and post test probability of the illness. ANCA is about 90% sensitive and about 98% specific for vasculitis. (C ANCA for Wegeners and P ANCA for MPA). Both are rare diseases occuring about 10 in a million.
So if we test a million random people with ANCA testing, about 10 will have vasculitis and 9 will test positive (true positive). However, since the specificity is 98%, it means 2% of remaining people will also test positive (False positive). 2% of 9.999 million is almost 20000 of all the people tested positive (9+20000=20009), almost 99.99% are false positive. So the post test probability of this test is useless if you are not suspecting the disease before ordering the test.
Coming to your question. I can think of a couple of scenarios.
A. Your case was proven TB (Sputum positive) and came with some feature suggesting vasculitis. Why would you think of a second disease like ANCA Associated Vasculitis in the same partient at the same time? If pre test probability of AAV was low, the test positivity is very likely false positive.
B. Your diagnosis of TB was emperical (eg fever, cough plus pulmonary nodules) with AAV an important differential (i.e the prestest probability of an AAV was high). If that was the condition, then a positive ANCA increases the post test probability.
The ANCA positivity can only be evaluated knowing your prestest probability. Obviously, steroids will only be given if you are quite sure of a diagnosis of AAV.
Your decision is therefore going to depend on which of the two situation you encountered.
regards
Ok thanks for your effort
But my case presented by constititutional manifestations, hemoptysis other non specific symptoms plus uncontrolled diabetes state Iam not doubt for tuberculosis and smear examined in three different places with different samples
But other possible diagnosis while waiting AFB results is vasculitis as the patient constiutional manifestations were pronounced plus his age 48 years with chronic ischemic heart disease forced me to ask about ANCA c
Pt received full course of antituberculous ttt with sputum conversion after 2 months and complete resolution of bilateral consolidation and cavitary lesions after 6 months without steroid therapy
4 months later constitutional symptoms again and knee and elbow effusion with no respiratory symptons no radiological shadows
Good evening,
could you give more info on the "ANCA positivity" in your case? Method: IF or ELISA?pattern and titer? PR3, MPO or other Ag?
Immunologically, ANCA in vasculitis have a monospecific target in a given patient. In drug-induced ANCAs and during chronic infections, ANCAs are usually polyspecific, variably targeting many Ags. The latter situation does not have the same ominous meaning as the former. Hence the importance of having a trusted laboratory to help you interpret the test.
Although ANCA are quite diagnostic for vasculitis in the proper clinical context, like most autoantibodies, they can be positive in chronic infections without vasculitis. That is the case for anti-CCP and anti-ENA in HIV patients without arthritis or any CTDs. In the latter, the ANCA pattern is often atypical and they will tend to go away with treatment of the infection.
They can also be drug-induced, the Ags are then elastase and MPO, giving either typical or atypical patterns in IF especially when the ANA series are also targeted.
The good evolution of your patient suggests you were right, in not "treating the test". If you had been wrong, your patient would not have survived.
That being said, after 6 months, if Tb has been eliminated i.e. cured, something else is starting. That will require a new rheumatological CTD work-up including an ANCA repeat and synovial fluid exam and culture.
About steroids, have you ever used them as a short-term measure, in a life threatening overwheming Tb infection at the beginning of anti-Tb treatment? I think that has been reported without the consideration of an ANCA-vasculitis. At histology, there is always some kind of vasculitis in any infected tissue.
So, my answer to your question, would be a sybillin "Tb with ANCA is not an a priori indication for steroids but, depending on the context, Tb without ANCA is not a contraindication for steroids".
I believe we need more data in a sequential fashion in this patient, as above-stated. Apparently he had culture-proven TB, and a positive ANCA test, ? pattern and specificity. A diagnosis of true idiopathic vasculitis would require a tissue diagnosis regardless of the ANCA test. There are several questions to be answered, as raised by the other authors,
steroid indications for patient with tuberculosis especially those with extrapulomary tuberculosis will known and approved but i ask for another indication of addon steroid if tuberculosis is the cause of ANCA associated vasulitis
Is your diagnosis of vasculitis based just on a positive ANCA test, or is it biopsy-proven, e.g., coming from a lung biopsy? I suppose this is the first question; an ANCA test can be nonspecific and also be drug-induced,
Great, my finding is ANCA positivity in a case of evident pulmonary tuberculosis with recent arthritis, joint effusion , uveitis and acute coronary syndrome with evidence by cardiac cath.
Hi,
Thanks for the clinical f/up. Please add irequested nfo (test methods, Ag Targets and titers) on initial and f/up ANCA tests. Best.
HM
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