Problems of differential diagnosis in dermatology using the example of polyangiitis of a single organ and papulonecrotic tuberculosis of the skin

Papulonecrotic tuberculosis of the skin is a rare form of tuberculosis infection caused by Mycobacterium tuberculosis or Mycobacterium bovis, which manifests as inflammatory nodules with necrosis in the centre. This form of tuberculosis occurs in two clinical variants: superficial and deep, characterised by varying degrees of severity of skin changes and a tendency to form atrophic 'stamped' scars after the rashes have cleared. Diagnosis of papulonecrotic tuberculosis of the skin is a complex task. The superficial form of tuberculosis of the skin should be differentiated from secondary syphilis, the deep form - from tertiary syphilis. Papulonecrotic tuberculosis of the skin should also be differentiated from the papulonecrotic form of dermal vasculitis. Diagnostic methods include radiological examination, skin biopsy followed by histological and immunohistochemical analysis, and specific tuberculin tests (T-SPOT.TB, Diaskintest et al.). The present article describes a clinical case of a patient with chronic inflammatory skin lesions of the lower extremities who was initially diagnosed with vasculitis. However, further comprehensive investigation, including histological studies and consultation with a dermatopathologist, led to the final diagnosis of papulo-necrotic tuberculosis of the skin.