Scrofuloderma: report of two cases

Tuberculosis (TB) is a chronic, granulomatous, infectious disease caused by the Mycobacterium tuberculosis complex. Cutaneous TB accounts for less than 1-2% of all TB cases. Scrofuloderma is a subcutaneous form of cutaneous TB, which results from direct spreading of infection from deeper tissues.

We present two patients with scrofuloderma who exhibited typical clinical features but posed significant diagnostic challenges. In the first case, diagnosis was confirmed by polymerase chain reaction (PCR) of a tissue specimen which detected M. tuberculosis. All other microbiological tests, including direct microscopy, acid-fast bacilli smear, mycobacterial cultures, and TB-PCR of caseous discharge, were negative. In the second case, M. tuberculosis was identified via PCR of an ulcer swab, while other tests were negative. Histopathological findings were consistent with cutaneous TB. Both patients were treated with four first-line antitubercular drugs. The first patient developed progressive leukopenia and neutropenia and the treatment was adjusted to exclude ethambutol. Both the patients showed significant clinical improvement shortly after starting therapy.

Cutaneous TB is often misdiagnosed due to its rarity and the challenges of microbiological testing, especially in paucibacillary forms. Histopathological features, though suggestive, are not pathognomonic, contributing to diagnostic delays. Increased awareness among dermatologists can lead to earlier diagnosis and better outcomes.