Case 3:
A five-month-old boy was presented to the pediatric department as his parents had noticed a progressive swelling and erythema on the left thigh from one month ago. On physical examination vital signs were stable. There was a swelling sized 4*4 cm on the left thigh and the site was warm. No deformity, discharge, or tenderness was detected. The general physical examinations including lung and heart auscultation, abdominal examination, and the examination of lymph nodes were normal. He had received oral Metronidazole and Amoxicillin-Clavulanic acid for one week without any improvement. The patient had an appropriate growth and developmental history with no prenatal or perinatal difficulties and he had received the routine vaccination for Iranian children. The lab results were as follows: WBC: 39000/μl, Hemoglobin: 9.8 gr/dl, Platelet: 510000, and ESR: 21 mm/h. BUN and Cr were normal. Ultrasound results demonstrated a hypo-echoic lesion with internal septations (46*37*47 mm, approximately 42 ml, 10 mm under the skin). X-ray imaging was otherwise normal. Open surgical drainage was done and samples were sent for gram staining, acid-fast staining, culture, and PCR examination of various mycobacterium types. Clindamycin was administered after admission to cover possible causes of abscess and due to inappropriate response, it was changed to Vancomycin and Cefotaxime. Gram staining and routine culture were negative. Acid-fast staining and culture on Loewenstein Jensen culture media were both positive for mycobacterium. The PCR test result was positive for Mycobacterium Bovis. TST was done and showed 0 mm induration. Isoniazid and Rifampin were administered after the diagnosis of the mycobacterial cold abscess was confirmed. During the next two weeks, regarding the thigh swelling and possible pus re-accumulation, ultrasound examination of thigh soft tissue was repeated and showed an abscess (approximately 9 ml, 19 mm under the skin), so the patient underwent surgical drainage and debridement of the lesion for the second time. Isoniazid and Rifampin were continued for the next six months. The patient had good growth and development with no further re-accumulation of pus or any other remarkable health problem during the follow-up.