Lichenoid tuberculid is cutaneous tuberculosis frequently associated with lymph nodal or systemic tuberculosis.
According to sudden eruption, symmetrical distribution, tuberculosis in the pathological examinations, and sometimes acid-fast bacillus, but negative vaccination, it is considered to be hematogenously disseminated tuberculosis. However, the results of tuberculin tests are negative, the pathological changes are mainly epithelioid cells, and most patients are not with tuberculosis in other parts, and it is also believed to be a sarcoid reaction.
Signs and Symptoms
Sudden onset is present. Skin lesions are pea sized, brownish purple flat papules, mainly distributed symmetrically in the extremities, sometimes with fine scales at the top, sometimes annular or clustered, leaving brown pigmentation after healing, without scars.
Some tuberculous nodules in the upper dermis are visible, and occasionally caseous necrosis can be seen.
On the basis of sudden lichenoid eruption in extremities and results of histopathology, diagnosis is not difficult.
Treatment regimen is gold sodium thiosulfate intracutaneously once a week and vitamin D2 50,000 IU twice a day, until the regression of the skin lesions.