Intermediate or Borderline Forms (BT, BB, and BL)

Abstract

Leprosy is a long-term spectrum disease and can present various clinical and histopathological aspects. Between the two poles of leprosy, there is a wide range of types, consisting of intermediate or borderline forms. In this chapter, the clinical, histopathological, and bacilloscopic characteristics of the intermediate forms (borderline-tuberculoid [BT], borderline-borderline [BB], and borderline lepromatous [BL]) are presented and discussed. The main clinical and pathological characteristics that allow the diagnosis and classification of leprosy among the different borderline forms are described and illustrated in panel form, as well as their most significant clinical and histopathological differential diagnoses are also discussed. The clinicalpathological classification of this disease has important implications in the choice of the correct treatment, the understanding of the pathophysiology, and the development of the reaction phenomena typical of leprosy.

Keywords: Borderline lepromatous, Borderline tuberculoid, Hansen’s disease, Leprosy, Mid-borderline.

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