Lewandowsky's Rosaceiform Eruption: a Form of Cutaneous Tuberculosis Confirmed by PCR in Two Patients.

introductionCutaneous tuberculosis (TBC) is a chronic disease caused by Mycobacterium tuberculosis, and is present in less than 1-2% of all TBC cases. The current problem with diagnosis is the demonstration of bacillus in the skin, especially paucibacillar forms, where sources like polymerase chain reaction (PCR) have improved diagnostic capacity. CASE PRESENTATION: Two cases of cutaneous TBC are reported. The first patient was 52-year-old woman with facial erythematous papulo-nodular lesions which had been developing for 4 months, and had previously been treated as acne rosacea, with partial response. Histopathological studies showed chronic granulomatous inflammation. TBC was suspected, so PCR was performed, which showed positive for M. tuberculosis. The second case was a 43-year-old woman with a facial rosaceiform plaque which began 6 months previously, and was treated as rosacea without any change for 5 months. Skin biopsy and PCR were positive for TBC. Both cases were treated using primary schedule for TBC, and both presented a favorable response. DISCUSSION: A clinical profile called Lewandowsky's rosacea-like eruption has been previously described. The condition has been questioned for years and was later removed from the spectrum of tuberculids and cutaneous TBC for not being able to isolate microorganisms in skin samples, a situation that might now change. In paucibacillar forms, when culture and staining are negative and TBC is still suspected, it is recommended to use DNA amplification by PCR for an accurate diagnosis. Both cases bring up the concern about once again bringing Lewandowsky's rosaceiform eruption into the spectrum of cutaneous TBC, and the discussion about the current definition of tuberculid.