Papulonecrotic Tuberculid with Positive Acid-fast Bacilli
An 11-year-old Chinese boy presented to our clinic with recurrent ‘boils’ on his face, forearms, and thighs without low fever or cough since last month. The boils were non-tender. His uncle got the diagnosis of pulmonary tuberculosis for half a year. Physical examination revealed pea-sized to coin-sized (0.5 cm to 2.0 cm in diameter) atrophic and crusted ulcers symmetrically located around his face, forearms, and thighs, interspersed with varisized papules, nodules, and pustules []. Routine hemogram, urinalysis, liver and renal profiles were within normal limits. The erythrocyte sedimentation rate was 5 mm/hour. Culture of the sputum and urine were negative for Mycobacteria. A chest X-ray examination was performed, and cord-like shadow was found in the middle lobe of right lung and showed ‘sclerosis.’ The laboratory test of purified protein derivative (PPD) was strongly positive (72 hours): 30 × 30 mm. The Mycobacterium tuberculosis antibody (TB-IgG, produced by Beijing WANTAI Biological Pharmacy Enterprise Co., Ltd.) was positive. Biopsy specimen taken from a large crusted ulcer on the left forearm showed focal epidermal necrosis, below which lay an area of caseous necrosis, surrounded by a dense, palisade of inflammatory infiltrate filling the entire dermis that included histiocytes, lymphocytes, neutrophils, and numerous multinucleate giant cells []. The dermal vessels showed evidence of vasculitis. Positive acid-fast bacilli were found []. GMS stain and PAS stain were negative for fungi. Mycobacterium tuberculosis DNA sequences were confirmed by real-time polymerase chain reaction (Real-Time PCR) using slices of wax block of the lesion. In view of the clinical, laboratory parameters, and the histopathology, a diagnosis of PNT was made. The boy's weight was 33.5 kg. Treatment was begun with isoniazid, 300 mg/day, pyrazinamide, 750 mg/day, and rifampin, 450 mg/day, for 2 months and was followed by isoniazid, 300 mg/day, and rifampin, 450 mg/day, for 4 months. One month later, all the lesions regressed obviously. There was no recurrence for 8 months after the cessation of treatment. He is currently still on follow-up.