Clinical and histopathological activity in paucibacillary leprosy patients after fixed-duration multidrug therapy.

In 37 clinically-diagnosed borderline-tuberculoid (BT) leprosy patients skin biopsies were done prior to starting multidrug therapy (MDT) and at the end of 6 months therapy. Clinical and histopathological activity, graded as active, resolving and inactive, were studied at the end of 6 months of MDT. Of the 37 clinically-diagnosed BT patients 24 could be confirmed by histopathology as having BT leprosy, while the other 13 biopsies showed features of indeterminate (I) leprosy. After 6 months of MDT, out of the 24 histopathologically-confirmed BT patients, 4 (17%) showed clinical activity and 8 (33%) showed histopathological activity. Of the 13 histopathologically-diagnosed indeterminate cases all were clinically inactive but histological activity persisted in 3 cases (23%). Out of the 37 clinically-diagnosed BT patients 3 showed both clinical and histopathological activity at the end of MDT. This study emphasizes the importance of performing histopathological examinations on leprosy patients undergoing research studies for the confirmation of diagnosis and for proper classification of the disease. The histopathological activity that outlasts the MDT may be due to the bacillary fragments that persist but clinical activity coupled with histopathological activity seen in 3 patients at the end of 6 months may foreshadow a relapse and these patients and others like them need to be followed up for longer durations.