We report a case of a 1-year-old girl with persistent fever and enlargement of laterocervical lymph nodes on the left side, fluctuant and with erythematous overlying skin. A positive Mantoux skin test first (induration of 20 mm in 72 hours) and then the DNA amplification by polymerase chain reaction (PCR) as well as the culture confirmed the diagnosis of Mycobacterium tuberculosis complex, in particular M. bovis. Nonetheless, after 1 month of standard mycobacterial regimen (isoniazid, rimpaficin, ethambutol, pyrazinamide), she developed new lymph nodes on the same and on the opposite side, apart from the residual ones. She underwent surgery three times (excision of a lymph node, incision and drainage of the others) for the definitive diagnosis and for the excessive enlargement of the nodes with risk of compression of underlying structures and diffusion. A drug resistance was ruled out by antibiogram. Paradoxical upgrading reaction (PUR) to the therapy offers a plausible explanation for this phenomenon, and this is supported by a prompt answer to steroids.
