Papulonecrotic Tuberculid with Positive Acid-fast Bacilli
A 24-year-old Chinese female presented to our clinic with recurrent ‘boils’ around her thighs without low fever or cough since the last 4 months. The boils were non-tender, and some of them had healed spontaneously, leaving behind unsightly scars. Her grandmother got the diagnosis of pulmonary tuberculosis several years ago. Physical examination revealed pea-sized (0.3 cm to 0.5 cm in diameter) crusted papules symmetrically located around both her thighs, interspersed with nodules and pustules of similar size []. Routine hemogram, urinalysis, liver and renal profiles were within normal limits. The erythrocyte sedimentation rate was 25 mm/hour. Culture of the sputum and urine were negative for Mycobacteria. A chest X-ray and computed tomography examination were performed, and a cord-like shadow in the upper lobe of right lung was also found. The laboratory test of PPD was positive (72 hours): 20 × 20 mm. The Mycobacterium tuberculosis antibody (TB-IgG) was positive too. Ultrasound of her abdomen and pelvis were reported normal. Biopsy specimen taken from a crusted papule on the left thigh showed focal epidermal necrosis, below which lay an area of caseous necrosis, surrounded by a distinct, mixed inflammatory infiltrate filling the entire dermis that included histiocytes, lymphocytes, and multinucleate giant cells []. The dermal vessels showed evidence of focal lymphohistiocytic vasculitis. Positive acid-fast bacilli were also found []. GMS stain and PAS stain were negative for fungi. Mycobacterium tuberculosis DNA sequences were also confirmed by Real-Time PCR in the lesion. In view of the clinical, laboratory parameters, and the histopathology, a diagnosis of PNT was made. Treatment was also started 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. Significant clinical improvement was noted within one month. There was no recurrence for 5 months after the cessation of treatment. She is currently still on follow-up too.