Lower lobe disease was found in these two latter reports to be more commonly associated with younger patients, specifically below the age of 40 years. The association of unusual roentgenographic disease with advanced age has also been questioned in two recent studies. Indeed, the increased occurrence of “unusual” disease at an earlier age was believed to reflect progression of primary tuberculosis and as such, was not necessarily unexpected. Hadlock et al suggest that the increased reporting of unusual roentgenographic appearances actually represents the increased frequency of primary disease within the adult population. Reports of patients with AIDS having concomitant pulmonary tuberculosis have drawn attention to the frequent occurrence of unusual radiologic disease. Several of these patients have had solitary anterior segment infiltrates. Unusual roentgenographic disease in this group may well be a manifestation of recently acquired infection, ie, primary disease.
Tuberculous disease of the anterior segment, while previously reported infrequently, is nevertheless well documented. Most often anterior segment disease has been reported as a manifestation of primary disease; however, our cases demonstrate that anterior segment disease may be found in reactivated states as well. Why tuberculosis should choose to reactivate in this area of the lung is unclear; its rarity might suggest an element of randomness. It may be a manifestation of spread from less visible prior disease in the apical and/or posterior segment, regions of the lung more frequently associated with reactivation disease. Some cases are undoubtedly examples of endobronchial tuberculosis. This condition has been associated with reactivation cavitary disease, although more recent studies have suggested an association with primary disease as well.
The importance of the unusual roentgenographic localization of tuberculosis lies in its potential to be overlooked in the pursuit of an alternative diagnosis, particularly malignant neoplasms. In fact, several textbooks of infectious diseases and pulmonary diseases suggest that anterior segment postprimary tuberculosis is a “rare” phenomenon. An overall incidence of 6.3 percent of all patients in our series would suggest a more frequent occurrence than previously appreciated. While our study does not confirm unequivocally a link between anterior segment disease and advanced age and alcoholism, the association with diabetes appears to be significant. It would seem prudent to advise particular vigilance with regard to the exclusion of tuberculosis in any patient with anterior segment roentgenographic changes, particularly where diabetes, advanced age, and alcoholism may coexist.