Retiform Hemangioendothelioma

Retiform hemangioendothelioma typically presents in adults as an ill-defined plaque of the distal extremities, although involvement of other areas of the body has been reported. The tumor consists of elongated vessels involving the dermis and extending into subcutaneous tissue. The endothelial cell lining is cuboidal or hobnailed in appearance. These tumors are regarded as low grade malignancies; however, lymph node involvement has been reported.

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Slide 1: 65 year-old woman with an abdominal lesion. R/O angiolipoma. Within the subcutaneous fat there is a very distinct vasoformative tumor. Even at low power, we can identify organizing thrombi.

Slide 2: The thrombi have undergone a hyalinizing fibrosis with dystrophic calcification.

Slide 3: The main vasoformative component has a hybrid morphology including delicate septal-like structures almost reminiscent of interalveolar septa of the lung with accompanying pseudoalveolar spaces. There is a more solid pattern of growth whereby in such areas the pattern of vascular proliferation is one which assumes a retiform one.

Slide 4: TDelicate septal-like structures almost reminiscent of interalveolar septa of the lung with accompanying pseudoalveolar spaces and adjacent more solid pattern of growth.

Slide 5: There is a concomitant proliferation of smooth muscle as well amidst the vasoformative channels in areas that have a more retiform appearance but as well spindled cells are present within the delicate septal foci.

Slide 6: Organizing thrombi with adjacent vasoformative delicate septal-like structures.

Slide 7: Smooth muscle proliferation amidst the vasoformative channels.

Slide 8: Smooth muscle cells are present within the delicate septal foci as well.

Slide 9: Vasoformative channels that have a more retiform appearance.