Kaposiform Hemangioendothelioma

Diagnosis

Kaposiform Hemangioendothelioma

Diagnosis

Kaposiform Hemangioendothelioma

History

Incidental finding of a left 8th rib lesion on chest X-rays in a young boy.

Findings

Very discrete lesion in the anterior aspect of the left 8th rib suggestive of a benign process. Low dose CT images 196-201; Fused images 194-201; CTAC images 242-249.

Discussion

Vascular lesions in infants and children include malformations and tumors. The most common ones are congenital infantile hemangiomas.
Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor found in infants.
Clinically, they present themselves as enlarging and painful masses.
A recent meta-analysis reported a median age at diagnosis of 5 months, with almost 70% of cases in patients less than 1-year old. Lesions occurred in the extremities in 20-30% of cases, trunk in 20-50% and head and neck in 25%. Median size of the lesion is 27 cm2 with some up to 600 cm2. A frequent complication is the Kasabach-Merritt phenomenon (KPM), a consumptive coagulopathy yielding to severe thrombocytopenia, hypofibrinogenemia and microangiopathic anemia which occurs in two-thirds of patients.
Characteristic findings on magnetic resonance imaging are heterogeneous speckled hypointense lesions on T2 weighted sequences, with ill-defined margins.
The only case imaged with FDG was in a 22 year-old patient presenting herself with an abdminal mass and only minimal FDG upatake as in our patient, suggestive of mesenteric paniculitis.
Pathology findings includes tissular infiltration by spindle endothelial cells , congested capillaries, positivity for vascular CD31/ CD34 and lymphatic D2-40/LYVE-1/Prox1 biomarkers and negativity for GLUT-1 and WT-1.
Differential diagnosis includes among others, infantile hemangioma, tufter angioma and kaposiform lymphangiomatosis . The latter occurs mostly in the mediastinum and lungs, in older patients but is also associated with KPM.
As spontaneous regression does not occurs with KHE and due to the complications , systemic treatment including steroids, vincristine, sirolimus or interferon alpha is needed. Other options are surgery, embolization and radiotherapy or a combination of local and systemic approaches.KHE in the retroperitoneum, while infrequent has a worse prognosis due to local complications and KMP.

Key points

Unusual lesion with low uptake.

References

1. Kaposiform hemangioendothelioma in children: a benign vascular tumor with multiple treatment options. Schmid I et al . World Journal Ped 2018;14:332-329
2. Vascular Tumors in Infants: Case Report and Review of Clinical, Histopathologic, and Immunohistochemical Characteristics of Infantile Hemangioma, Pyogenic
Granuloma, Noninvoluting Congenital Hemangioma, Tufted Angioma, and Kaposiform Hemangioendothelioma. Johnson EF et al. Am J Dermatopathol 2018;40:231-239
3. Clinical and imaging features of Kaposiform Hemangioendothelioma. Hu PA. Br J Radiol 2018;91:20170798
4. Kaposiform lymphangiomatosis and kaposiform hemangioendothelioma:
similarities and differences. Ji Y et al. Orphanet J Rare Diseases 2019;14:165-173
5. Kaposiform hemangioendothelioma: current knowledge and future perspectives. Ji Y et al. Orphanet J Rare Diseases 2020;15:39-556. Imaging findings of Kaposiform Hemangioendothelioma in children. Ryu YJ et al. Eur J Radiol 2017;86:198-2057. Abdominal Kaposiform Hemangioendothelioma Associated With Lymphangiomatosis Involving Mesentery and Ileum. A Case Report of MRI, CT, and 18F-FDG PET/CT Findings. Dong a et al. Medicine 2016;95:e2806