Selective tuberculin anergy: case report and review

: Because of the human immunodeficiency virus epidemic, skin testing for Mycobacterium tuberculosis is now performed in conjunction with control skin tests to assess anergy and thus provide information to aid in the interpretation of a negative tuberculin test. However, anergy can occur selectively to purified protein derivative tuberculin when reactions to other recall antigens are present. We report an illustrative case of selective anergy in a patient with tuberculous meningitis and review the literature on this poorly understood phenomenon. When one suspects M. tuberculosis disease, repeating a 5 unit PPD-tuberculin skin test after four to eight weeks of antituberculous treatment may assist in establishing or excluding the diagnosis of tuberculosis.