Rare case of Kaposiform haemangioendothelioma of spine associated with fixed hyperlordotic deformity: a report

Kaposiform haemangioendothelioma (KHE) is a rare childhood disease classified by the International Society for the Study of Vascular Anomalies (ISSVA) as a locally aggressive vascular tumor. It has been reported to affect any site, with a predilection for the extremities and trunk.

KHE can manifest at any site, most frequently in the extremities and trunk, as an enlarging firm, purpuric cutaneous or soft tissue lesion with telangiectasia that typically crosses multiple tissue planes. Skin involvement is not present in approximately 10% of cases, with the retroperitoneum being the most frequently involved extracutaneous site.

Despite its limited metastatic potential, KHE is associated with a high rate of morbidity due to its locally invasive characteristics and compressive effects. It can also give rise to Kasabach-Merritt phenomenon (KMP), a potentially fatal thrombocytopenic coagulopathy associated with a risk of severe microangiopathic anemia.

Approximately twenty cases of KHE with bony involvement have been reported in the literature to date, with only five of those cases involving the spine specifically.

Leanne H. Q. Chin presents a rare case of KHE who presented with progressive fixed hyperlordotic deformity, multiple non-specific spinal lesions, and abnormal blood tests, posing a clinical and radiological diagnostic challenge.

A previously healthy 9-year-old boy was referred for abnormal gait. At the age of seven, he first complained of an acute episode of spontaneous lower back pain lasting 2–3 days, with persistent back stiffness affecting lumbar flexion. He had normal bladder and bowel movements with no associated numbness or weakness, but also presented with easy bruising and gum bleeding.

During physical examination, he was found to have a waddling gait and a fixed hyperlordotic deformity with anterior pelvic tilt. Apart from localised tenderness over the back during palpation, other clinical examinations were unremarkable.

Laboratory investigations revealed significant thrombocytopenia (Platelet count 19×10^9/L), mild anaemia (Haemoglobin level 10.0 g/dL, mean corpuscular volume (MCV) 73.4fL), normal white blood cell count (8.23× 10^9/L), normal prothrombin time (12.9 s), activated partial thromboplastin time (31.1 s), and international normalized ratio (1.1). Human leukocyte antigen (HLA)-B27 was negative.

Skeletal survey showed lordotic deformity of the lumbosacral spine, multiple sclerotic bone lesions involving the vertebral bodies and pedicles of T12-L3, sacrum, bilateral iliac bones and acetabulum. There was no pathological fracture or vertebral collapse. Displacement of bilateral paravertebral stripes were noted from T9–T12 levels. Magnetic resonance imaging (MRI) reveals scattered multi-level T1 and T2 iso-to-hypointense lesions involving both the vertebral bodies and posterior elements from T10 to sacrum, corresponding with sclerotic changes seen on the plain radiographs. These lesions showed surrounding T2 hyperintense signals and contrast enhancement as well. In the surrounding soft tissues, there were also ill-defined infiltrative T2 hyperintense signals with contrast enhancement seen involving the anterior and posterior paraspinal soft tissues including the retroperitoneum, bilateral psoas and posterior paraspinal muscles. There was also diffuse involvement with abnormal contrast enhancement of bilateral sacroiliac joints in a symmetrical fashion without overt joint space widening, erosion or ankylosis. There was also mild thickening of the anterior epidural space from L5 to S1. No signs of central cord, cauda equina, or nerve root compressions were seen.

Given the presence of "marrow lesions" on imaging and suspected bone marrow failure, the initial working diagnosis was underlying haematological disease such as myeloproliferative disorders. Bone marrow aspiration and trephine biopsy was subsequently done, but only showed non-diagnostic findings of active trilineage hematopoiesis, reactive plasmacytosis and non-specifc stromal damage suggestive of granulomatous inflammation.

Mantoux test, angiotensin converting enzyme (ACE) levels, metabolic screen and tumour markers were all negative. Whole body fuorodeoxyglucose (FDG)-positron emission tomography (PET)-computed tomography (CT) showed low grade metabolic FDG activity along the affected paraspinal soft tissue components (SUVmax 1.8; liver and mediastinal blood pool references SUVmax 1.4 and 1.0 respectively), but no metabolic activity in the associated bones.

Bilateral sacroiliac joints also show mild increased FDG activity (SUVmax 2.1) with no other abnormal uptakes elsewhere. Findings remained nonspecifc and differentials such as chronic infection (e.g. TB spondylitis), Langerhan cell histiocytosis, small round cell tumours and lymphoma were proposed.

Due to inconclusive results, CT-guided biopsy with platelet transfusion was performed after multidisciplinary team discussion. The patient was placed in prone position under conscious sedation. The lumbar bony site was biopsied using 11-gauge powered bone access system, obtaining three tissue cores. Paraspinal soft tissue was biopsied using 18-gauge core biopsy needle in a coaxial fashion, obtaining three tissue cores. Cores of tissue composed of cellular and reticulin-rich islands of spindle-shaped endothelial cells was seen on light microscopy. These formed slit-like vascular channels containing hemosiderin deposits and intravascular microthrombi in a fibrotic background. The tumour cells were arranged in short fascicles within the cellular islands with a whorl-like pattern. Lymphatic channels were inconspicuous with scanty bony fragments seen. Immunohistochemical (IHC) staining was focally positive for both vascular endothelial markers (CD34, CD31 and ERG), lymphatic endothelial markers (D2-40), and SMA. GLUT-1 and HHV8 are negative. The Ki67 index was low. Final histopathological diagnosis was suggestive of Kaposiform haemangioendothelioma.

Medical therapy with sirolimus followed by interval MRI reassessment was recommended after multidisciplinary consensus. Surgery was deemed not feasible at the time due to extensive involvement, and radiotherapy was not advocated in view of its adverse effects on spinal growth. Prior to the starting of sirolimus treatment, fibrinogen levels were checked and found to be low 1.52 g/L, consistent with Kasabach-Merritt syndrome. Both the fibrinogen levels and platelet counts showed significant improvement within two months of starting treatment without the need for transfusion.

Further reading:

Kaposiform haemangioendothelioma of the spine associated with fixed hyperlordotic deformity and Kasabach–Merritt Syndrome: a case report and literature review Chin, L.H.Q., Fung, K.K.F., Chan, J.P.K. et al. Skeletal Radiology https://doi.org/10.1007/s00256-022-04152-z