Cavernous hemangioma-like kaposi sarcoma: histomorphologic features and differential diagnosis

Abstract

Aim. Cavernous hemangioma-like Kaposi sarcoma is a rare morphologic type of Kaposi sarcoma. So far there are no cases in the literature defining the histological features of this morphologic spectrum in detail. In this study we presented two classical-type cutaneous Kaposi sarcoma cases with histologic findings resembling cavernous hemangioma in company with clinical and histopathological data. Cases. One hundred and eighty-five classical-type cutaneous Kaposi sarcoma lesions in 79 patients were assessed retrospectively in terms of histopathological features. Findings of two cases showing features of cavernous hemangioma-like Kaposi sarcoma whose clinical data could be accessed were presented in accompany with the literature data. Both cases were detected to have bluish-purple, protruded, irregularly bordered cutaneous lesions. Histopathological examination revealed a lesion formed by cavernous hemangioma-like vascular structures organized in a lobular pattern that became dilated and filled with blood. Typical histological findings of early-stage KS, consisting of mononuclear inflammation, extravasated erythrocytes, and a few immature vascular structures in superficial dermis, were observed. All cases were serologically HIV-1 negative. A positive reaction with HHV-8, CD31, CD34, and D2-40 monoclonal antibodies was identified at both cavernous hemangioma-like areas and in immature vascular structures. Results. Cavernous hemangioma-like Kaposi sarcoma is a rare Kaposi sarcoma variant presenting with diagnostic challenges, that may be confused with hemangioma. As characteristic morphological features may not be observed in every case, it is important for diagnostic purposes to show immunohistochemical HHV-8 positivity in this variant.

Figure 1

Biopsy samples of both cases reveal lesions composed of dilated vascular structures with blood-filled lumen. (a)-(b) Hematoxylin and Eosin (×40).

Figure 2

Microphotographs of both cases show the characteristic findings of early-stage Kaposi sarcoma surrounded by mononuclear inflammatory cells adjacent to cavernous hemangioma-like vascular structures. (a)-(b) Hematoxylin and Eosin ((a) ×40; (b) ×100).

Figure 3

(a) Vascular structures with a thick wall are relatively well demarcated from the surrounding dermis. (b) Vascular proliferation is in close neighborhood to skin adnexae. (a)-(b) Hematoxylin and Eosin (×100).

Figure 4

(a) Hemosiderin pigment is seen both on the walls of cavernous hemangioma-like vascular structures and in the stroma. (b) A positive immune reaction with HHV-8 is evident in endothelial cells. (a) Hematoxylin and Eosin (×100), (b) LSAB-DAB (×100).

Figure 5

The anastomosing vascular structures contain flattened endothelial layer giving a positive immune reaction with HHV-8. (a) Hematoxylin and Eosin (×100), (b) LSAB-DAB (×100).