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Table 2 Clinical and histopathological characteristics of the main leprosy lesions considered as diagnostic hypotheses that resulted in biopsies with a subsequent diagnosis of dermatofibromas originating in leprosy lesions

From: A case series of dermatofibromas originating in leprosy lesions: a potentially misdiagnosed condition

  Relapse T1Ra (RR)b T2Rc (ENL)d Histoid leprosy Drug resistance
Course Recurrence 1 year or more after withdrawal of treatment Usually within 6 months of withdrawal of treatment; in recurrent reactions, up to 2 years Can occur any time during the course of leprosy, but is most common within 1 year of starting PCT Patients who discontinued treatment or had resistance to sulfone Initial amelioration followed by halt or worsening
Leprosy lesions All types BT, BB, BL LL side (LL and BL) LL side (LL and BL) LL side (LL and BL)
Skin lesions Increase in size and extent of existent lesion(s); new lesion(s); reappearance of lesions over old lesions; ulcerations not seen Existing lesions become tumid and erythematous; distribution: locations of existing lesions; ulcerations seen in severe reactions New erythematous dermal and/or subcutaneous nodules; painful and tender; distribution: upper and lower extremities, trunk, face Skin-colored papules and nodules; bacillary proliferation and morphologically solid bacilli within fusiform macrophages Appearance of new lesions with bacillary proliferation and morphologically solid bacilli
Nerves Nerve involvement; no spontaneous pain; tenderness on pressure; sensory and motor deficits slow and creeping; bacillary proliferation Acute painful neuritis; nerves exquisitely tender; nerve “abscess” (caseous necrosis); sudden paralysis of muscles and increase in extent of sensory loss Similar to T1R, but with influx of neutrophils and formation of microabscesses and absence of caseous necrosis None Bacillary proliferation
Treatment Retreatment with standard PCT or drug change if resistance is detected Prednisone (start at 0.5–1.0 mg/kg) NSAIDs Azathioprine Cyclosporine Thalidomide (start at 100–200 mg daily) Clofazimine Prednisone Pentoxifylline TNF-alfa inhibitors Retreatment with standard PCT or drug change if resistance is detected Retreatment. New drugs are used according to the definition of which of them previously used resulted in resistance by M. leprae
  1. LL lepromatous, PCT polychemotherapy, I indeterminate, TT tuberculoid, BL borderline lepromatous, BB borderline borderline, BT borderline tuberculoid, NSAIDs nonsteroidal anti-inflammatory drugs
  2. aType 1 reactions; bReversal reaction; cType 2 reaction; derythema nodosum leprosum