Skeletal and extraskeletal angiomatosis with Kasabach-Merritt Syndrome. Report of a case

Background & Objective: Angiomatosis is general term employed to describe a spectrum of rare pathologic conditions characterized diffuse infiltration of bone, soft tissue and viscera by vascular channels filled with lymph or blood. We describe a case of paediatric angiomatosis with extensive skeletal and extraskeletal involvement, and consumption coagulopathy type Kasabach-Merritt syndrome (KMS). Method: A 3-year-old boy presented with a one-month history of left lower limb pain and swelling of the ipsilateral knee. At birth, multiple haemangioma of the soft tissues of the scalp were identified, and a lesion consistent with pulmonary sequestration was detected at chest CT scan. MRI studies revealed multiple lesions of the left femur, with soft tissue extension, of the left tibia and the right femur. A surgical biopsy was taken from the left femur, which was reported as non-diagnostic. One week later the mother reported bleeding from the site of the biopsy. Blood tests demonstrated anaemia, thrombocytopenia and both decreased and consumption of coagulation factors, consistent with KMS. Results: A new biopsy of the femur showed a proliferation of thin-walled, dilated blood vessels, in between the bony trabeculae, as well as in the cortical bone and in the adjacent soft tissues. The endothelial lining was devoid of atypia, and immunoreactive for CD31 and CD34, while podoplanin and GLUT1 were negative. Conclusion: Distinction of skeletal angiomatoses as discrete entities is difficult and has led to an array of confusing conditions with similar appearances at histology, with variable involvement of skeletal and extraskeletal sites.