Papillary Endothelial Hyperplasia (Masson Tumor)

 PEH lacks nuclear atypia, tumor cell necrosis, and mitotic activity present in angiosarcoma



• Hemangioma

• PEH-like changes may occur in hemangiomas complicated by thrombosis

• Arteriovenous malformation (AVM)
image PEH-like changes may occur in background of AVM

• Hematoma

• Venous lymphatic malformation (VLM)
image In VLM, there are lobules of abnormally dilated vessels, some with lymphatic morphology



image
Well-Circumscribed Vascular Proliferation
Papillary endothelial hyperplasia (PEH) is a well-circumscribed reactive lesion in which papillary fronds image lined by a single layer of endothelial cells proliferate within a vascular lumen image.


image
Fibrin Thrombi Seen in PEH
Fibrin thrombi image are apparent in early stages, and with time are replaced by papillary fronds with a fibrous core lined by a single layer of banal-appearing endothelial cells image characteristic of PEH.

image
PEH With Single Layer of Flat Endothelium
The lined endothelium image is a single layer of evenly spaced, banal-appearing flat cells wrapping around the fibrotic core image.

image
Some Cases of PEH Can Resemble Angiosarcoma
PEH can be mistaken for the dissecting vascular spaces seen in low-grade angiosarcoma. Note the bland endothelial lining image of the blood vessel lumen and intravascular location.


TERMINOLOGY


Abbreviations




• Papillary endothelial hyperplasia (PEH)


Synonyms




• Masson tumor

• Vegetant intravascular hemangioendothelioma

• Intravascular angiomatosis

• Intravascular papillary endothelial hyperplasia


Definitions




• Benign, reactive, and papillary endothelial proliferation within vessel


ETIOLOGY/PATHOGENESIS


Reactive Vascular Proliferation




• Manifestation of organizing intravascular thrombus

• PEH-like changes may be present in preexisting hemangiomas or vascular malformations


CLINICAL ISSUES


Site




• Wide distribution

• Common sites include: Head and neck, fingers, trunk


Presentation




• Painless mass

• Located in deep dermis &/or subcutaneous tissue


Treatment




• Excision is not necessary but is curative


Prognosis




• Excellent

• Cases with underlying hemangioma or vascular malformation may recur


MACROSCOPIC


General Features




• Cystic mass with red-purple discoloration

• Often surrounded by pseudocapsule


Size




• Mostly small (< 2 cm)


MICROSCOPIC


Histologic Features




• Circumscribed lesion with pseudocapsule
image Residual smooth muscle or elastic lamina of preexisting vessel may be apparent

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Papillary Endothelial Hyperplasia (Masson Tumor)

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