Tuberkulid

Tuberkulid is a term used to describe a specific type of skin reaction that can occur in individuals who have a known or suspected infection with tuberculosis (TB). It is not a disease itself, but rather a hypersensitivity response to the bacteria that cause TB, primarily Mycobacterium tuberculosis. This reaction is considered a manifestation of a delayed-type hypersensitivity, indicating that the immune system has been sensitized to the tuberculosis bacillus.

The term tuberkulid is generally applied to a group of exanthematous skin eruptions that are often lichenoid, papular, or nodular in appearance. These eruptions are typically found on the extremities, such as the arms and legs. The lesions are often small and may be itchy. They are not infectious and do not contain the tuberculosis bacteria themselves. Instead, they are thought to arise from the deposition of antigen-antibody complexes in the skin.

Diagnosis of tuberkulid is often made based on the characteristic appearance of the skin lesions in conjunction with a history of or active tuberculosis infection. It is important to distinguish tuberkulid reactions from other skin conditions and from direct cutaneous tuberculosis, which is a much rarer form of the disease where the bacteria are present in the skin. Treatment of tuberkulid focuses on treating the underlying tuberculosis infection. Once the systemic TB is managed, the skin lesions typically resolve on their own.