Teaching Case

A 30-year-old male presenting with a nine month history of worsening nocturnal right hip pain. A sitting position aggravates his pain and over-the-counter anti-inflammatory medication relieves his pain.

Figure 1: AP pelvic radiographs of the pelvis show that a lytic expansile lesion with a shell type periosteal reaction is present within the right superior pubic ramus, extending into the inferior pubic ramus and medial wall of the right acetabulum. The superior and inferior borders are indistinct.
Figure 2: Coronal T1-weighted post gadolinium MR of the pelvis demonstrates 4.5 x 3.0 x 4.0 cm multi-lobulated avidly enhancing lesion in the right anterior acetabulum and the right pubic ramus.
Figure 3: Non-contrasted axial image of the pelvis showing percutaneous biopsy approach to the pelvic lesion.
Figure 4: Pre-embolisation angiogram of the pelvic vasculature from the right iliac artery cannulation.
Figure 5: Post gel-foam embolisation angiogram of the right pelvic vasculature.
Figure 6: Immunohistochemistry positive CD13 and SMA confirming the final pathological diagnosis of epithelioid haemangioma of the bone.

Background:
Early middle-aged patient with 9 months of worsening right hip pain presented to the orthopaedic clinic for work-up. Physical examination was unremarkable.

Imaging Perspective:
Pelvic and right hip radiographs showed an expansile lytic lesion with shell type periosteal reaction involving the right superior and inferior pubic rami and the anterior acetabulum.

Follow-up pelvic MR showed a 4.5 x 3.5 x 4.0 cm multi-lobulated avidly enhancing lesion within the right anterior acetabulum and superior pubic ramus, with an associated expansion of the osseous structures. Pathological fracture was present in the anterior column.

Clinical Perspective:
CT guided biopsy of the right acetabular bone lesion was performed and samples sent to pathology for characterisation. Final diagnosis of epitheliod haemangioma was made by immunohistochemical stains.

Patient underwent right iliac angiogram with subsequent embolisation of right inferior gluteal, obturator, and inferior branches of the superior gluteal artery. Following the procedure, complete intralesional curettage with operative polymethylmethacrylate fixation of the right anterior column was performed by the orthopaedic service.

Teaching points:
Epithelium based vascular tumours are controversial due to challenging differentiation between various types, including haemangioendothelioma, angiosarcoma, lymphangioma, fibrous dysplasia, and atypical metastasis [1, 2]. It is vital to discern between the tumour types because of their behaviour, and consequential treatment differences [3]. Epithelioid haemangiomas are lobulated or multinodular in growth and benign in skin, but may occur in the metaphysis or diaphysis of long bones [3, 4].These tumours are rare and are characterised by vascular proliferation with endothelial and inflammatory cells and typically occur in the head or scalp [5, 6]. These tumours present most often in adults with only a few reported paediatric cases [4]. A high index of clinical and an imaging index of suspicion is needed in conjunction with immunohistochemistry to successfully diagnose EH, especially one in an a-typical location [2]. Once diagnosed, trans-arterial embolisation should be performed as pre-treatment prior to any surgical intervention to reduce tumour size for an easier operative excision, and reduce intra-operative risk of massive haemorrhage.