In this case, a 31-year-old female presented with progressive pain and decreased range of motion of her left hip over 2 months, and the pain had increased progressively and worsened with activity. During the 2 months, the patient reported fever and had self-administered cephalosporin antibiotics. She had no history of chills, fatigue, weight loss, or other systemic symptoms. However, she mentioned her husband was being treated for "tuberculosis". Physical examination revealed pain in flexion, adduction, and external rotation of the left acetabulum, but no swelling, local skin damage, ecchymosis, or obvious local deformity. It showed no respiratory and neurologic symptoms or signs. Laboratory investigations showed a serum C-reactive protein level of 67.51 mg/L, total white blood cell count of 7700/mm3 with 86.8% neutrophils, and erythrocyte sedimentation rate of 64 mm/h. The viral serology tests for hepatitis B yielded positive results and suggested chronic hepatitis B. The HIV screening, Mycobacterium tuberculosis antibody, and Mycobacterium tuberculosis DNA tests were all negative.
Radiographs demonstrated a 3 cm purely lytic lesion in the left acetabulum without sclerosis or periosteal reaction. The continuity of the local cortical bone was interrupted, and the adjacent soft tissues were inflamed (Fig. 1a). Computed tomography (CT) scan showed osteolytic bone destruction of the left acetabulum with clear borders and no sclerosed margins, and a soft tissue mass measuring 3.5 cm by 2.0 cm by 3.3 cm in the left acetabulum. The average CT value was approximately 44HU (Fig. 1b, c). The wall was strengthened with a CT value of 76HU, and there was a liquid low-density shadow in the mass with a CT value of 23HU, and no enhancement was seen (Fig. 1d, e). Three-dimensional reconstruction showed bone destruction in the left acetabulum (Fig. 1f). Chest CT showed bullae at the apical segment of the right upper lobe, with the remainder of the chest showing no obvious abnormalities. Magnetic resonance imaging (MRI) showed irregular bone destruction and abscess formation in the left acetabulum, with the abscess measuring 3.6 cm by 1.9 cm by 3.5 cm, cortex erosion and significant bone and soft tissue edema were also observed (Fig. 2a-c). The presence of enhancement at the edge of the lesion and an area of liquefaction necrosis without enhancement in the center indicate abscess formation (Fig. 2d-f). Imaging diagnosis of infectious disease with abscess formation.
The mass was sampled by fine-needle aspiration biopsy under ultrasound guidance. Histopathological examination of the specimen showed granulomatous inflammation surrounded by a large number of multinuclear giant cells, some lymphocytes, and plasma cells (Fig. 3a, b), and the presence of Cryptococcus was confirmed by periodic acid-Schiff's reaction (Fig. 3c). The resulting histopathological diagnosis was granuloma with Cryptococcus.
After one month of antifungal treatment with fluconazole and flucytosine, a fungal culture from diseased tissue secretions produced a negative result. Upon discharge, the left leg was placed under traction and immobilized to prevent hip dislocation and relieve the pain, and we continued the antifungal treatment. A follow-up of MRI after 10 months confirmed a decrease in the lesion's size (from 3.6 cm by 1.9 cm by 3.5 cm to approximately 2.7 cm by 1.6 cm by 3.1 cm), but there was still some bone defect in the left acetabulum (Fig. 4).