Isoniazid Induced Cutaneous Leukocytoclastic Vasculitis in Extra Pulmonary Tuberculosis (Pott's Spine): A Case Report.

Anti-tuberculosis drugs frequently result in cutaneous adverse reactions but Isoniazid is known to have least toxic potential for cutaneous reactions. We report a rare case of Isoniazid induced cutaneous leucocytoclastic vasculitis. A 64-year-old male was diagnosed to have Pott's spine with multiple vertebral body involvement (D8-12 vertebrae). Subsequently, he was treated with first line anti-TB drugs i.e., Isoniazid, Rifampicin, Pyrazinamide and Ethambutol. On the fourth day of treatment with Anti Tuberculosis Treatment (ATT), the patient developed an erythematosus rash over right upper limb not associated with itching or pain, non-blanchable macules and papules over bilateral shins on lower limbs, petechiae on both forearms and hyper pigmented, scaly rash over right axilla and buttocks. The skin biopsy report was consistent with cutaneous leukocytoclastic vasculitis. Although rare, Isoniazid among anti-tuberculosis drugs should be considered as potential cause of drug-induced cutaneous leukocytoclastic vasculitis in the differential diagnosis of erythematosus rash with petechiae.