Incidental Simultaneous Finding of Intravascular Histiocytosis and Reactive Angioendotheliomatosis

Abstract

Reactive angioendotheliomatosis (RAE) is a rare cutaneous vascular disorder characterized by intravascular hyperplasia of endothelial cells, sometimes with a vascular proliferation. Intravascular histiocytosis (IH) is a similar vascular disorder characterized by the presence of dilated vessels containing aggregates of mononuclear histiocytes (macrophages) within their lumina. Although their pathogenesis remains uncertain, there has been speculation about the possible relationship between IH and RAE. We report a case of coexistence of RAE and IH in a patient who underwent a wide reexcision of a metastatic malignant melanoma. The excision specimen did not show any residual melanoma but exhibited an intravascular collection of CD-68-positive histiocytes admixed with CD-31-positive endothelial cells and fibrin surrounded by D2-40-positive vascular wall. The presence of intravascular cells initially raised concern of intravascular invasion by melanoma. As there was no clinical lesion and immunohistochemical stains for melanocytic makers were negative, we interpret this as an incidental finding. Knowledge of this benign vascular disorder is important because the histologic changes may be mistaken for intravascular invasion of a malignant neoplasm.

Hobnail cell change in reactive angioendotheliomatosis, a potential diagnostic pitfall

“…2003). Many patients present with symptoms like fever and weight loss for which systemic examination is done to rule out the underlying systemic disease (Aung et al, 2015;Gupta et al, 2020). Laboratory findings show raised erythrocyte sedimentation rate (Lazova et al, 1996).…”

Case Report of Reactive Angioendotheliomatosis

“…[1][2][3] On histopathology, RAE demonstrates a benign intraluminal proliferation of endothelial cells that may occlude the vascular lumen. [4][5][6] In addition, the vessels are usually dilated. 4 The upper subcutaneous fat might demonstrate vascular occlusion with cells and fibrin.…”

“…[4][5][6] In addition, the vessels are usually dilated. 4 The upper subcutaneous fat might demonstrate vascular occlusion with cells and fibrin. 2 The intravascular cells are positive for factor VIIIrelated antigen, CD31, and CD34.…”

“…2 The intravascular cells are positive for factor VIIIrelated antigen, CD31, and CD34. 4 Initially, RAE was divided into benign and malignant variants. The malignant variant, incorrectly named malignant DISCUSSION angioendotheliomatosis, has now been redefined as angiotropic large cell lymphoma/intravascular large B-cell lymphoma, an intravascular type of malignant lymphoma.…”

“…3 The majority of the intraluminal cells expresses positive CD68 and negative CD31/CD34 with marked dermal edema and perivascular inflammatory infiltrate. 4,11 Other important clinical entities to consider include Kaposi's sarcoma and angiosarcoma. Kaposi sarcoma (KS) presents initially as erythematous, violaceous bilateral and symmetric patches, typically on the lower extremities.…”