Case 1:
A four-month-old girl was presented to our hospital due to a right thigh swelling since four days ago. The parents did not report any fever, poor feeding, or irritability. On physical examination vital signs were stable. There was a 5*7 cm fluctuating mass with sharp borders at the anterior surface of her right thigh (Figure 1). No erythema, deformity, discharge, or tenderness was detected. Both hips and knees had a normal range of motion. The general physical examinations including lung and heart auscultation, abdominal examination, and the examination of lymph nodes were normal. There was no history of insect bite or trauma. The patient had an appropriate growth and developmental history with no prenatal or perinatal difficulties. She had received the routine vaccination for Iranian children that included BCG, the first dose of hepatitis B, the first dose of OPV (Oral Polio Vaccine), and the first dose of DPT (Diphtheria, Pertussis, and Tetanus). The lab results were as follows: White Blood Cell (WBC): 11500/μl (Polymorphonuclear leukocyte (PMN): 29% and Lymphocyte: 66%), Hemoglobin: 9.6 gr/dl, Platelet: 519000/μl, and Erythrocyte Sedimentation Rate (ESR): 50 mm/h. Blood Urea Nitrogen (BUN), Creatinine (Cr), Blood Sugar (BS), and electrolytes were normal. Ultrasound results demonstrated a large collection of thick fluid (49*29*32 mm) with debris and septations in the depth of the anterior thigh muscle. X-ray imaging was otherwise normal.  On the first day of admission needle aspiration of the lesion was done and 5 milliliters of green purulent fluid was drained and sent for gram staining, acid-fast staining, and culture. Gram staining and routine culture were negative. The patient received intravenous Cloxacillin without significant improvement and so open surgical drainage was done and light yellow cheesy material was drained and sent for acid-fast staining. Both samples sent for acid-fast staining showed more than 10 acid-fast bacilli per field. On Loewenstein Jensen culture media, light yellow slow-growing colonies were reported. The patient had no abnormal findings on chest Computed Tomography (CT) scan and immunological screening tests. The patient received Isoniazid, Rifampin, and Ethambutol with diagnosis of mycobacterial cold abscess and there was no improvement after three weeks. Clarithromycin was added and the patient improved significantly after two weeks. These medications were continued for four months and Isoniazid and Rifampin for further two months. The patient had good growth and development with no further re-accumulation of pus or any other remarkable health problem during the one-year follow-up.