A 10 year old boy presented with a 4 months history of pain in the left hip.
The patient had no history of preceding trauma or accident.
On clinical examination, there are no local tenderness, no swelling or mass, and no systemic symptoms. There is also no impairment of the function of the hip or other joint and no neurologic defect.
A radiographic image of the pelvis revealed a large osteolytic and loculated lesion in the left iliac wing and sacrum with well-defined geographic margins (Fig 1).The diagnosis of giant cell tumour or eosinophilic granuloma was advocated.
CT showed an aggressive lytic lesion involving and destroying left iliac wing and sacrum with a presacral soft-tissue component (Fig 2). It extended into the vertebral canal through the neuroforamen of the L5-S1 and S1-S2 spines and it compressed dural sleeve without infiltrative appearance. There is no periosteal reaction.
The lesion marked an heterogeneous enhancement After contrast material administration and its size is 81x55.6x82.7 mm.
Open biopsy was performed that lead to the diagnosis of benign fibrous histiocytoma (BFH).
Benign fibrous histiocytoma (BFH) is a tumour that occurs predominantly in the skin and most commonly in younger individuals. The tumour typically presents as a painless nodule varying in size from a few millimetres to several centimetres [1].
BFH of the bone has been a subject of increasing interest within the past few years. The term was initially introduced by Dominok in 1980 to describe a cystic lesion in the femur of a 66 year old man [2]. Only a few cases of BFH of bone have been described in the literature since then. Its occurrence in pelvic bones is even rarer [3,4] and it accounts for approximately 1% of all surgically managed benign bone tumours [5]. Histologically, BFH arising from soft tissues cannot be distinguished from those arising from bone [6].
Several names were given to the BFH: fibrous histiocytoma, xanthofibroma, fibroxanthoma of bone, and primary xanthoma of bone. Its exact nature remains somewhat controversial. A lesion may be designated a benign fibrous histiocytoma based on clinical, radiographic, and microscopic criteria [7].
Peak incidence of BFH arising from bone is reported in the third decade [8].It is most common in the metaphysis of long bones [9]. Pain is most often the predominant presenting symptom [6], which helps to distinguish this tumour clinically from other fibrous lesions, such as non ossifying fibroma. In addition, non-ossifying fibroma nearly always manifests in patients less than 20 years of age [11].
On radiography the lesion is characterized by osteolytic and loculated lesions with a well defined sclerotic margin [4]. There is no matrix mineralization and the zone of transition of the lesion is narrow. Various benign lesions such as non ossifying fibroma, giant-cell tumour, fibrous dysplasia, aneurysmal bone cyst and eosinophilic granuloma are included in the differential diagnosis [7].
Computed tomographic (CT) scan typically shows fibrous osteolytic lesions with cortical thinning and no periosteal reaction. [10]. There have been reported cases of aggressive lesions with local spread and dissemination [11]. Soft tissue invasion are rarely seen.
Magnetic resonance (MR) Imaging of BFH usually shows low signal intensity on T1- and high signal intensity on T2-weighted images. Peripheral contrast enhancement has also been described in BFH [12,13,14].
Positive bone scans may be helpful in differentiate BFH from non ossifying fibroma [12].
Biopsy is mandatory to confirm the diagnosis: Histologically BFH represents a benign but diverse group of neoplasms that are characterized by both fibroblastic and histiocytic differentiation [15]. It may be difficult to differentiate BFH from low-grade malignant fibrous histiocytoma. Lack of marked pleomorphism or of atypical mitoses is suggestive of a benign diagnosis [3].
Treatment consists of careful and complete curettage and filling of the defect with graft material, bone cement, or other suitable bone void filler. A local recurrence rate of 5-25 % is reported in literature. The recurrence rate is typically related to the size of the tumour [3,16]. Consequently, careful clinical and radiological follow-up including regular MRI is recommended [3].
Benign fibrous histiocytoma
Based on the provided X-ray and CT images, there is a well-defined lytic lesion in the left hip region (left side of the pelvis). The focus shows focal destruction with possible thinning of the local cortical bone, but no definite cortical disruption or significant soft tissue swelling is observed. The lesion appears relatively localized, with a surrounding sclerotic rim. No obvious osseous matrix calcification or distinct periosteal reaction is noted.
Considering the child is 10 years old, with left hip pain for 4 months, along with the imaging characteristics and clinical presentation, the main differential diagnoses are as follows:
Taking into account the following factors:
• The child is 10 years old, with prolonged left hip pain (4 months);
• Imaging shows a lytic lesion with a clear boundary, associated sclerosis, and no obvious soft tissue infiltration;
• If pathology (if biopsy or histopathological results are available) indicates a benign lesion composed of fibrous cells and histiocytes;
The most likely diagnosis is: Benign Fibrous Histiocytoma (BFH) of bone origin.
If there is still uncertainty, further MRI or histopathological examinations are recommended to confirm the diagnosis.
Treatment Strategy:
1. If confirmed by histopathology as BFH, the primary choice is thorough curettage of the lesion, followed by filling of the defect with autograft or allograft bone, bone cement, or other suitable bone substitute materials, depending on the size of the defect.
2. For larger lesions in challenging locations, or in cases of recurrence or suspicion of malignant transformation, more aggressive surgical interventions may be considered.
3. Postoperative follow-up imaging (including MRI) is recommended at regular intervals to monitor for local recurrence or healing progress.
Rehabilitation/Exercise Prescription:
• Early Stage (postoperative or upon initial diagnosis, during early recovery):
a. Focus on protecting the affected area and avoid excessive weight-bearing on the involved bone.
b. Under the guidance of a physician or physical therapist, perform gentle range-of-motion exercises for the hip joint (e.g., passive and active movements in seated or supine positions).
c. Use supportive devices or crutches to reduce stress on the hip joint, and engage in short, low-intensity walking exercises as necessary.
• Middle Stage (when the lesion is stable/when there is obvious postoperative bone healing):
a. Continue monitoring hip function recovery and gradually increase weight-bearing activities.
b. Perform muscle-strengthening exercises (such as resistance band training) to enhance stability of the hip’s surrounding muscle groups. Adopt low-load, high-repetition exercises for safety.
c. Include core strengthening exercises (such as straight leg raises, bridging) to maintain trunk stability.
• Late Stage (good recovery, local stability achieved):
a. Based on the progression of bone healing, gradually incorporate higher resistance exercises (e.g., gym equipment, ankle weights) in a stepwise manner.
b. Integrate aerobic exercises such as swimming or cycling, which improve cardiopulmonary function while avoiding excessive impact on the joint.
c. Follow the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, Progression) and progressively increase activity volume and intensity each week according to individual tolerance.
d. Remain alert for any hip pain or discomfort. If marked discomfort occurs, seek medical evaluation promptly.
Disclaimer: This report is a reference-based analysis derived from the current information and cannot replace an in-person consultation or professional medical advice. If you have any questions or if your condition changes, please consult an orthopedic surgeon, oncologist, or a relevant specialist promptly.
Benign fibrous histiocytoma
