A number of reports over recent years have drawn attention to the unusual roentgenographic presentations of pulmonary tuberculosis. With few exceptions, these reports have given little attention to tuberculous involvement of the anterior segment of the upper lobes. Anterior segment involvement is relatively common in primary disease of childhood, but it is less frequent in adulthood. Moreover, anterior segment disease, when apparent in the adult, is generally understood to signify “recent infection,” ie, adult-onset primary tuberculosis. Unfortunately, the reports documenting anterior segment disease have, with the exception of that of Woodring et al, seldom differentiated between primary and reactivation disease.
The present study noted an overall incidence of localized anterior segment involvement in 6.3 percent of patients. However, approximately half of this number actually had additional (though roentgenograph- ically minimal) disease in a single adjacent upper lobe segment. If these cases are excluded, four patients of the 142 had truly focal anterior segment disease, an incidence of 2.8 percent. The latter corresponds with incidence rates of 2 percent, 3.9 percent, and 1.8 percent in previous studies. An equal number of patients with isolated anterior segment involvement had primary and reactivation disease. When considered in the context of all cases exclusively involving the upper lobes, focal anterior segment disease occurred with an incidence of 7.1 percent and predominant anterior segment disease occurred in 16 percent of patients.
The persistence of reports detailing difficulties in the expeditious diagnosis of pulmonary tuberculosis supports the current preoccupation with unusual roentgenographic features of the disease. Furthermore, it has been suggested that there is greater difficulty in demonstrating the presence of tubercle bacilli from secretions of patients with unusual roentgenographic disease. Focal lesions such as tuberculomas may not be expected to shed large numbers of bacilli into the bronchial tree. Failure to demonstrate the presence of acid-fast bacilli from respiratory secretions in patients with lower lobe and supposedly “stable” upper lobe disease has been regarded as evidence of a low bacillary burden. Little difficulty in arriving at the diagnosis of tuberculosis was encountered with the group of patients with anterior segment involvement described in this report. Bacilli were readily demonstrated in sputa in all but one who required an open lung biopsy. Indeed, this patient (case 2) was noted on bronchoscopy to have occlusion of the orifice of the right anterior segment bronchus and had endobronchial tuberculosis on open biopsy. In keeping with a number of reports on endobronchial tuberculosis, findings from sputum examination were repeatedly negative.
Impaired host immunity has been regarded as a predisposing factor in the reactivation of tuberculosis in adult life. Classically, tuberculosis has been reported to occur more commonly during old age, diabetes, renal failure, corticosteroid therapy, malignancy, and chronic alcoholism. More recently the associations have broadened to include AIDS. Whether these associations also foster the development of tuberculosis at unusual roentgenographic sites in the lungs is not entirely clear. Unusual roentgenographic presentations, particularly involving the lower lobes, have been described in pregnancy, diabetes, and advanced age. However, Hadlock et al and Shachor et al were not able to confirm an association of diabetes mellitus and unusual roentgenographic tuberculosis. No cases of diabetes were described in two widely quoted reports of lower lobe disease.