Cryptic miliary tuberculosis refers to miliary tuberculosis that lacks the widespread mininodules that are the hallmarks of the disease. Failure to consider the diagnosis can result in delayed therapy or a missed diagnosis.


Features of cryptic miliary tuberculosis:

(1) The miliary tubercles are too small to be seen on imaging studies.

(2) The patient is often over 60 years of age.

(3) The patient may present with fever of unknown origin (FUO), unexplained fatigue, malaise or unintended weight loss.

(4) The patient may have pancytopenia or leukemoid reaction.

(5) The erythrocyte sedimentation rate (ESR) is often normal or only slightly elevated.

(6) Some patients will be afebrile or have an intermittent low-grade fever.

(7) The tuberculin skin test may be positive, borderline or negative.


Diagnostic tests that may help to establish the diagnosis:

(1) bronchoscopy with culture for acid fast bacilli or PCR

(2) liver biopsy with culture for acid fast bacilli

(3) bone marrow biopsy with culture for acid fast bacilli

(4) analysis of pleural or ascites fluid with culture of acid fast bacilli

(5) fundiscopic exam


In the past a trial of antituberculous therapy would be tried even in the absence of definitive findings. A patient with miliary tuberculosis will show a positive response after 1-6 weeks of therapy (afebrile, improved well-being, etc).


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