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Fifty-four patients with cutaneous tuberculosis, consisting of 23 with lupus vulgaris, 22 with scrofuloderma, and nine with verrucosa cutis, were investigated for cell-mediated immunity, through estimation of peripheral total T lymphocytes (CD3+), CD4+ (helper/inducer), and CD8+ (cytotoxic/suppressor) lymphocytes, by immunohistochemical staining of peripheral blood smears, using specific monoclonal antibodies and the alkaline phosphatase-antialkaline phosphatase (APAAP) method. Absolute values of total T lymphocytes (CD3+), and CD4+ and CD8+ subsets, were found to be significantly raised in scrofuloderma, but the percentage values and the CD4+/CD8+ ratio remained unaltered. In tuberculosis verrucosa cutis, only the percentage of the CD8+ subset of T lymphocytes was found to be significantly lowered, and this altered the CD4+/CD8+ ratio. No significant change was observed in the peripheral blood T cells and their subpopulations in patients suffering from lupus vulgaris.

During the past 3 years, we have seen a changing pattern of cutaneous tuberculosis, in which its incidence was recorded to show an upward trend affecting predominantly the adult men. The latter was true in reinfection--lupus vulgaris and tuberculosis verrucosa cutis, whereas a substantial number of children were victims of reactivation--scrofuloderma. The duration of the disease was usually short in reactivation tuberculosis. Its clinical expression, however, conformed largely to the ritual text except that apple-jelly nodules were infrequently demonstrated. Similarly, the morbidity was low. The affliction of the extremities in lupus vulgaris, in particular, was a contrasting feature. The histopathology invariably either confirmed or supplemented the clinical impression. The ultimate confirmation of cutaneous tuberculosis was done only by the demonstration of Mycobacterium tuberculosis in smears, or its recovery in vitro. In view of the limitations of the preceding parameters, the diagnosis may reasonably be made based on the history and evolution of the disease, cardinal morphologic features of reinfection and reactivation tuberculosis, and histopathologic characteristics. A response to antitubercular drugs may be of assistance.

Cutaneous tuberculosis incidence was recorded as 0.15%. Of the 42 patients, 23 had scrofuloderma, 17 lupus vulgaris, and 2 tuberculosis verrucosa cutis. Both men and women were affected by the disease in the second and third decades. Its duration was variable. An affirmative family history was elicited in five scrofuloderma patients. The clinical expression largely conformed to the ritual text. Variation in Mantoux test positivity was unremarkable. The disparity in the demonstration of bacilli in the smear and tissue sections was, however, quite apparent in scrofuloderma. The correlation of different parameters indicates a continuous spectrum, formed at one end by lupus vulgaris, and at another by scrofuloderma. A moderate to strongly positive Mantoux text, enormous lymphocytes in the granuloma, absence of tubercle bacilli, negative culture, and an apparently normal immunoprofile were features of lupus vulgaris; whereas scrofuloderma had a moderately positive Mantoux test, lesser number of lymphocytes in the granuloma, large number of bacilli in tissue smear and/or tissue section, raised levels of immunoglobulins, and a grossly lowered C3 levels. The other variants probably occupy a position in between.