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Respiratory Disorders (Expert Forum)
Lung infiltrates, negative Mantoux & blood test: Tuberculosis or differential?
Answered by
MN
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Lung infiltrates, negative Mantoux & blood test: Tuberculosis or differential?
by cynom, Mar 13, 2008 03:13PM
Dear Doctor
My brother [39] (smoker for 20 years, but quit about 3 weeks ago) complained of pains in his side (upper chest), coughed up a little bit of blood 2-3 times in the past week, and lost weight (not sure how much, but he claims he's fasted for about 3 weeks). 2 different radiologists think the lung/chest MRI and X-ray respectively 'look like TB', and show 'infiltrates' but Mantoux test was negative and blood test was negative for TB. Blood work suggests his white blood cell count is low (but I don't know the value).
Doctor wants to wait for sputum test to return (another 3 weeks), but in the meantime has prescribed TB medication. Is it possible that it's TB even though the other test suggest it is not? Should he take the TB medication? What is a possible differential diagnosis and is it prudent to wait another three weeks to get to the root of low white blood cell count and lung infiltrates? Could it be something more (or hopefully less!) serious? Any other diseases that mimic TB on xray?
Thank you
My brother [39] (smoker for 20 years, but quit about 3 weeks ago) complained of pains in his side (upper chest), coughed up a little bit of blood 2-3 times in the past week, and lost weight (not sure how much, but he claims he's fasted for about 3 weeks). 2 different radiologists think the lung/chest MRI and X-ray respectively 'look like TB', and show 'infiltrates' but Mantoux test was negative and blood test was negative for TB. Blood work suggests his white blood cell count is low (but I don't know the value).
Doctor wants to wait for sputum test to return (another 3 weeks), but in the meantime has prescribed TB medication. Is it possible that it's TB even though the other test suggest it is not? Should he take the TB medication? What is a possible differential diagnosis and is it prudent to wait another three weeks to get to the root of low white blood cell count and lung infiltrates? Could it be something more (or hopefully less!) serious? Any other diseases that mimic TB on xray?
Thank you
Doctor's Answer
by National Jewish Health, Mar 18, 2008 05:40PM
, Mar 18, 2008 05:40PM
The negative Mantoux (PPD) and negative blood test do not rule-out the diagnosis of tuberculosis. False negatives can and do occur. This could be related to your brother's low blood count. Has he been tested for the possibility of immunodeficiency? If not, this testing should be considered. In some populations smear negative disease is common. Thus, your brother may have tuberculosis (TB).
Blood testing, in a number of forms, has greatly increased our ability to establish a diagnosis. For example, a new type of invitro T-cell based assay, for the detection of TB was recently developed. This interferon gamma (IFN gamma) blood assay is based on the measure of IFN gamma production by previously sensitized lymphocytes in response to the M. tuberculosis (TB) specific proteins.
Other techniques have been developed, to enhance the sensitivity of sputum smear. For example the use of sodium hypochlorite (NaOCl) significantly enhances positivity of smear negative sputum, for the diagnosis of TB, when used with fluorescent microscopy.
The above tests could be done quickly, without a 3 week wait.
You asked, "Could it be something more (or hopefully less!) serious? Any other diseases that mimic TB on xray?" The answer is yes. A number of infections can mimic TB and these include:
1) Actinomycosis, caused by an anaerobic gram positive bacterium;
2) Nocardiosis; and
3) a number of fungal infections, including opportunistic fungal infection.
The decision to proceed with therapy for TB is best made by a lung specialist, also called a pulmonologist, preferably one with experience treating TB, who has access to all of your brother's clinical and lab information. This would also include the specialist's sense of rapidity of the presumed infectious process, the likelihood that it is TB, and the urgency of initiating treatment, lest it be rapidly progressive, if untreated. If you are anxious or unsatisfied with the current physician's recommendation, you could request a second opinion.
If your husband’s doctor would like to learn about the Mycobacterial Disease Consult Service, please share this National Jewish Medical and Research Center website address
http://www.nationaljewish.org/patient-info/progs/med/mycobacteria/consult.aspx.
This information includes a link to the mycobacterial consultation form, which your husband’s doctor is welcome to complete and submit for a second opinion.
Blood testing, in a number of forms, has greatly increased our ability to establish a diagnosis. For example, a new type of invitro T-cell based assay, for the detection of TB was recently developed. This interferon gamma (IFN gamma) blood assay is based on the measure of IFN gamma production by previously sensitized lymphocytes in response to the M. tuberculosis (TB) specific proteins.
Other techniques have been developed, to enhance the sensitivity of sputum smear. For example the use of sodium hypochlorite (NaOCl) significantly enhances positivity of smear negative sputum, for the diagnosis of TB, when used with fluorescent microscopy.
The above tests could be done quickly, without a 3 week wait.
You asked, "Could it be something more (or hopefully less!) serious? Any other diseases that mimic TB on xray?" The answer is yes. A number of infections can mimic TB and these include:
1) Actinomycosis, caused by an anaerobic gram positive bacterium;
2) Nocardiosis; and
3) a number of fungal infections, including opportunistic fungal infection.
The decision to proceed with therapy for TB is best made by a lung specialist, also called a pulmonologist, preferably one with experience treating TB, who has access to all of your brother's clinical and lab information. This would also include the specialist's sense of rapidity of the presumed infectious process, the likelihood that it is TB, and the urgency of initiating treatment, lest it be rapidly progressive, if untreated. If you are anxious or unsatisfied with the current physician's recommendation, you could request a second opinion.
If your husband’s doctor would like to learn about the Mycobacterial Disease Consult Service, please share this National Jewish Medical and Research Center website address
http://www.nationaljewish.org/patient-info/progs/med/mycobacteria/consult.aspx.
This information includes a link to the mycobacterial consultation form, which your husband’s doctor is welcome to complete and submit for a second opinion.
