Background: Spectral concept of leprosy has evolved from the histopathology of leprosy skin lesions.
Objective: To identify sensitive histopathological markers of leprosy, to enhance the specificity of clinical diagnosis of leprosy, and to continue research and training in leprosy in postelimination era.
Material and Methods: This study was carried out in a state government referral center for leprosy from April 2009 to March 2010. Paraffin sections of biopsies were stained with hematoxylin and eosin, Ziehl–Neelsen, and Fite stains, examined, and classified histopathologically according to Ridley–Jopling scale. All new cases of leprosy diagnosed based on presence of at least two of the three cardinal features of leprosy were included. Released from treatment cases, partially treated cases, and those with lepra reactions were not included in this study.
Result: Fifty-nine skin biopsies of newly diagnosed untreated leprosy cases over a period of 1 year were included. Of the total 59 patients, the distribution of various types of leprosy is as follows: polar tuberculoid (TTp) leprosy, 18.33% (n = 11); borderline tuberculoid (BT) leprosy, 28.33% (n = 17); mid-borderline leprosy, 6.66% (n = 4); borderline lepromatous (BL) leprosy, 30% (n = 18); polar lepromatous leprosy, 5%( n = 3); histoid leprosy, 5% (n = 3); indeterminate leprosy, 5% (n = 3). Of the 11 patients with TTp leprosy, 81.8% (n = 9) showed mature epithelioid cell granuloma; of the 17 patients with BT leprosy, 94.11% (n = 16) showed immature epithelioid cell granuloma. Of the 18 patients with BL leprosy, 83.33% (n = 16) showed macrophage granuloma. Of the 28 patients on tuberculoid pole, 82.16% (n = 23) showed lymphocyte predominant infiltrate. Of the 32 patients on lepromatous pole, 84.37% showed macrophage predominant infiltrate. Wide Fite staining was positive in 14.28% (n = 4) on tuberculoid pole and in 87.5% (n = 28) on lepromatous pole.
Conclusion: Histopathology remains the only practical and viable tool for diagnosis of specific subtype of leprosy. Mature epithelioid granuloma is the most sensitive indicator for tuberculoid leprosy, and grenz zone is the most sensitive indicator of BL leprosy. Diffuse infiltration of the dermis except for narrow subepidermal zone is the most sensitive indicator of lepromatous leprosy.
Granuloma, grenz zone, spectral concept