The patient was a 32-year-old man who, approximately 17 years previously, after a penicillin injection, had started to have pain, swelling and erythema in his right buttock. After several days, the lesion started to produce a yellow secretion and made an orifice. Over the years, the secretion continued but the pain, swelling and erythema resolved. The patient reported occasional swelling around the orifice and that discharge occurred when he pressed on the area.
He had no significant past or family history and had not taken any medication at the time of admission.
Approximately 7 years previously, excisional surgery was carried out on the lesion and malignancy was ruled out.
Two years previously, he underwent a whole body scan that revealed inflammatory bone disease and pelvic MRI with a fistula protocol showed septic arthritis with osteomyelitis and an 8 cm fistulous tract that originated from fluid in the right sacroiliac joint and extended posteriorly to penetrate the gluteal muscles with an external opening in the right buttock.
In the physical examination, vital signs at admission were: body temperature 36.8 C, blood pressure 100/65 mmHg, pulse 75 beats/min and respiration rate 18 breaths/min. Lung auscultation was clear. No lymphadenopathy was detected. There was a 3 cm hyperpigmented area with fullness on the right buttock and an orifice with a small amount of yellow secretion. In addition, past surgery scars were seen on the right buttock but there was no erythema or redness. There was no limitation in the range of motion of the right hip and the muscle force of both inferior limbs was 5/5. No other significant signs were found in the physical examination.
Laboratory data showed a high erythrocyte sedimentation rate (ESR; 15 mm/h) and normal C-reactive protein (CRP) levels, haemoglobin of 16.6 g/dl, 5,700/ml leucocytes with a normal differential count (36.7% lymphocytes, 57% segment, 6.3% mixed) and 203,000/ml platelets. Fasting blood sugar, complete urinalysis and the Brucella agglutination test were all normal. Urine culture was negative.
A Mantoux test was carried out and the result was positive, with a 15 mm duration after 3 days.
Chest radiography showed a calcified area in the right hilum and also a prominent left hilum. Anteroposterior radiography of the pelvis showed an increased density of the right sacroiliac joint (Fig. 1). Computed tomography (CT) revealed right sacroiliac joint fusion and decreased joint space and sclerosis (Figs. 2 and 3).
During hospitalization, initial antibiotic therapy was prescribed and urea and creatinine were checked daily until the culture results were During hospitalization, initial antibiotic therapy was prescribed and urea and creatinine were checked daily until the culture results were obtained obtained. When the culture results revealed the presence of Mycobacterium tuberculosis, a 4-drug anti-TB therapy encompassing rifampin, isoniazid, ethambutol and pyrazinamide was prescribed for 18-24 months, in addition to daily vitamin B6 and pantoprazole. Due to atypical signs and symptoms, such as the absence of acute and severe pain and no limitations in the range of motion, and the normal laboratory findings (except for the ESR), the diagnosis took a long time.
On the other hand, our patient was from Afghanistan and was racially similar to the Iranian race. As the culture of the sacroiliac region secretions was positive for Mycobacterium tuberculosis, the patient started anti-tuberculosis treatment and was also improved in follow-up. A CT scan of the lung showed pulmonary hilum pump, but ACE testing for the patient was negative.
After treatment, the symptoms decreased and the patient now has no secretions. After 2 years, follow-up MRI of the hip joint showed evidence of chronic osteomyelitis in the right side of the sacrum and iliac bone with decreased signal intensity in favour of fibrotic changes. After comparison with previous images, the signal intensity of bone and soft tissue was decreased but the size of the collection in the sacroiliac joint had not significantly changed.