Diagnostic Dilemma of Cutaneous Tuberculosis: Opening of the Pandora's Box

Tuberculosis in all forms, that is, pulmonary (PTB) or extrapulmonary (EPTB), is a universal health problem. Cutaneous tuberculosis (CTb) remains one of the least studied and often under-reported variants of EPTB because of its wide and protean clinical presentation. The diagnosis of CTb remains challenging because of lack of sensitive and specific investigations for its diagnosis. The sensitivity of some of the traditional tests is low because of low concentration of mycobacteria in paucibacillary lesions. Besides it is difficult to distinguish between M. tuberculosis (MTb) and other mycobacterial species in skin biopsies morphologically. Molecular methods may target either MTb DNA or RNA, and serve as promising tools in the diagnosis of various forms of CTb, with high sensitivity and rapidity. This review is focused on diagnostic challenges of CTb and to discuss various methods and newer technologies for diagnosing CTb. This will help the dermatologists and dermatopathologists to elucidate and accurately diagnose CTb from other infectious granulomatous dermatitis for appropriate timely treatment of the patient.