Although papillary endothelial hyperplasia may occur at almost any site, one of the
most common sites is the hand. It is generally regarded as a reactive vascular proliferation
i.e. exuberant form of organizing thrombus. Diagnosis of Masson tumor can be challenging
due to its close clinical, radiological and even histopathological resemblance to
angiosarcoma. We present seven cases of Masson tumor of the hand; wanting to reveal
its nature using new vascular markers and discuss the treatment options and expected
outcomes, present clinical and radiological features that may aid diagnosis and also
offer treatment plans. A multicenter retrospective study was performed between January
2014 and November 2019. Immunohistochemical stains of Glut1, WT1, ERG, CD31 and alpha
smooth muscle actin (ASMA) were performed on each cases. We found seven cases during
the examined period. 4 out of 7 cases were women. All lesions occurred in the hands.
3 out of 7 cases appeared in a previously present vascular malformation. All cases
were treated with surgical excision and the diagnosis of papillary endothelial hyperplasia
was made by histology. Pre-operative testing (radiograph/MRI/US/fine needle aspiration
biopsy) did not suggest the diagnosis of Masson tumor; however, aspiration cytology
could rule out malignancy. The proliferative endothelial cells proved to be Glut1
negative and WT1 positive and the accompanying pericytic cells were ASMA positive
in all cases. Though Masson tumor is a rare vascular lesion in the hand among other
vascular tumors, it should be considered in the differential diagnostics even in the
case of previously existing vascular malformation. WT1 positivity of the endothelial
cells and the accompanying pericytic cells raises the question whether the initially
reactive endothelial proliferation may transform into a true benign vascular tumor.
