A 54 year old man with haemophilia A (FVIII=9%) presented with pain and a palpable mass in the right iliac fossa. The patient mentioned that the mass increased in size since last year and especially during last months.
On examination, a mass in the right iliac fossa was palpated.The mass was painful and increased in size since last year,although the patient mentioned that the first time he palpated it was approximately 2 years ago.There was a slight injury in this region,according to his sayings.A CT was performed.
The axial non-contrast CT demonstrates a large expansile lytic lesion with soft tissue attenuation and calcifications that involves the right iliac bone and extends into the pelvis (Fig 1). The next step was MRI. An axial T1WI (with fat suppression) of the pelvis shows a large mass with inhomogeneous signal intensity,due to existing blood products in various stages of organisation (methemoglobine with high signal in T1, fluid, and fibrosis). A low signal rim is demonstrated, because of hemosiderine deposition (Fig 2).
On axial contrast enhancement T1WI with fat suppression the lesion shows absence of enhancement.Moreover, one can see the iliac vessels displaced to the left, as a result of the mass extension (Fig 3). Therefore, a magnetic angiography was obtained, and showed in more detail the displacement of the right common, external and internal iliac artery to the left (Fig 4).
Haemophilic pseudotumours are uncommon, developing in 1-2% of patients affected with haemophilia. In most cases there is a prior history of trauma to the region. The pseudotumour represents a chronic, expanding haematoma with blood products in varying stages of organization, surrounded by a fibrous capsule.
The majority of the pseudotumours are contained within the soft tissues, most within muscles. There are also osseous pseudotumors, less common, developing within the medullary cavity or in a subperiosteal location.In most cases,the involved bones are the femur, pelvis (as in this case), tibia and hand bones.
Pseudotumours are radiographically variable. They are typically lytic, expansile lesions, may cause erosion of the adjacent bone(as in our case the right iliac bone), which may mimic a more aggressive lesion. MR imaging of the lesion demonstrates heterogeneous T1 and T2 signal due to blood products contained(showed in figures 2 and 3). MR is useful to delineate the extent of the lesion, as in this case with the displacement of iliac vessels.
Despite the variable imaging findings hemophilic pseudotumours may demonstrate, lesions with these characteristic findings in the clinical setting of a severe coagulopathy may be confidently diagnosed. The differential diagnosis includes many entities both benign (aneurysmal bone cyst, infectious processes, solitary bone cyst) and malignant (metastasis, osteosarcoma, malignant fibrous histiocytoma etc.).Therefore, clinical information is of great significance.
Treatment may vary from conservative (correction of coagulopathy) to aggressive (surgical excision), as in our case. Percutaneous biopsy or drainage is contraindicated due to complications, such as haemorrhage, infection or fistula formation.
Hemophilic pseudotumor,treated with surgical excision
Based on the provided CT and MRI images, the following can be observed:
• A large space-occupying lesion is visible in the right iliac fossa region, with an irregular shape and relatively clear boundaries, showing localized expansile changes.
• MRI indicates heterogeneous T1 and T2 signals, suggesting that the lesion contains blood or clots from different stages of hemorrhage.
• The lesion is adjacent to the right iliac bone, displaying local bone compression and erosion.
• The lesion significantly occupies the pelvic cavity, with evidence of pushing or displacing surrounding vessels (including the iliac vessels).
• Considering the patient’s long-term coagulation disorder (Hemophilia A), the mass has relatively well-defined borders and is suspected to be a chronic hematoma encapsulated by fibrous tissue.
Taking into account the patient’s age, established history of Hemophilia A (with a Factor VIII level of about 9%), the typical expansile and destructive nature of the lesion, and the mixed signal characteristics on MRI indicative of hemorrhage in different stages, the most likely diagnosis is: Hemophilic Pseudotumor.
Treatment Strategy:
• Correction of Coagulation Function: Primarily ensure adequate levels of clotting factors (e.g., supplementation or infusion of Factor VIII) to reduce bleeding risk.
• Surgical Intervention: For large pseudotumors threatening surrounding nerves and vessels or causing severe symptoms, surgical removal can be considered. In this case, if the lesion exerts marked pressure on local structures, surgery combined with clotting factor administration to reduce surgical risks is a proactive approach.
• Avoid Simple Puncture or Drainage: Without professional expertise and sufficient coagulation support, puncture or drainage carries a high risk (bleeding, infection, fistula formation, etc.).
Rehabilitation and Exercise Prescription:
Given the patient’s hemophilia background and potential surgical or conservative treatment outcomes, a “gradual and individualized” approach is crucial for safety. The following training outline is for reference:
1. Postoperative/Acute Phase (first 2–4 weeks): Focus on static exercises and mild activities, avoiding large joint movements or collisions. Simple bodyweight resistance exercises may be performed.
2. Recovery Phase (4–8 weeks): Once coagulation function is stable, gradually introduce moderate-intensity aerobic exercises such as walking or using a stationary bike. Each session may last 20–30 minutes, 3–5 times per week.
3. Enhancement Phase (after 8 weeks): If the tumor is resected or the lesion has regressed and stabilized, introduce light weight-bearing resistance exercises to maintain muscle strength (15–20 minutes per session, 2–3 times per week) combined with aerobic workouts. Avoid overuse that may lead to reinjury or bleeding.
4. Individual Adjustments: Adjust the intensity and type of exercise based on the patient’s bone health and bleeding frequency. Monitor for any pain, swelling, or joint stiffness. Discontinue exercise and seek medical evaluation if abnormalities occur.
This report is based solely on the current imaging and medical history available, and it does not replace face-to-face consultation or the final opinion of professional physicians. If the patient’s condition changes or further diagnosis and treatment are needed, please seek timely medical attention and follow the guidance of specialized healthcare providers.
Hemophilic pseudotumor,treated with surgical excision
