21 October 2015 - Case of the Week #368

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Case of the Week #368

Clinical history:
An HIV seronegative, 96 year old African-American woman with no remarkable past medical history presented with a left upper eyelid lesion, which was completely excised.


Gross description:
The specimen consisted of skin and mucosa-covered soft tissue. Immediately subjacent to the hairy edge was a 0.7 x 0.5 x 0.5 cm indurated nodule, with a mottled brown tan cut surface.


Micro images:


What is your diagnosis?































Diagnosis:
Kaposi sarcoma of the eyelid


Discussion:

Histological assessment showed a circumscribed stromal tumor (figure 1) with the typical morphology of Kaposi sarcoma, with spindle cells forming vascular spaces, extravasated red blood cells and occasional hyaline globules (figures 2-4).

Special stains were obtained:



Figure 5: Strong CD 34 immunostaining
Figure 6: Strong CD 31 immunostaining illustrating immunoreactivity of both spindle cells and endothelial component
Figure 7: Strong nuclear immunoreactivity for HHV8 in both spindle cell component and endothelium
Figure 8: Proliferation marker (Ki-67)

Immunohistochemical studies showed strong reactivity with the vascular differentiation markers CD31 and CD34, as well as with HHV8, the latter of which is uniquely associated with Kaposi sarcoma (in contrast to other vascular sarcomas). Ki-67 revealed 40-50% reactivity.

Kaposi sarcoma (KS) was first described in 1872 as an uncommon tumor that principally affected the skin of the lower extremities of elderly patients. There are now four clinical forms recognized: classic (statistically and significantly associated with a second malignant tumor or altered immune state), endemic (African), iatrogenic (transplantation associated) and AIDS related. Despite apparent differences, epidemiologic data strongly pointed to an infectious etiology for all. Human herpesvirus 8 (HHV8) is now considered the causative agent for all forms of Kaposi sarcoma. KS is generally considered to be a multicentric (rather than metastatic) and reactive hyperplasia rather than a true sarcoma, though this has been a subject of debate (J Am Acad Dermatol 2008 Aug;59:179).

Ophthalmic involvement by KS is rare, and is usually AIDS associated. Eyelid involvement accounts for roughly 15% of ocular manifestations of Kaposi sarcoma (Eyelid Tumors: Clinical Evaluation and Reconstruction Techniques, 2014). Clinically, ophthalmic KS present as purplish red to bright red patches, plaques or papules on the eyelid or conjunctiva. The clinical differential includes basal cell carcinoma, blepharitis, hemagioma and subconjunctival hemorrhage, among others (Eyelid Tumors: Clinical Evaluation and Reconstruction Techniques, 2014).

Histopathology shows spindle cells forming slit-like vascular spaces, extravasated red blood cells and occasional PAS positive hyaline globules, which may be extracellular or intracellular. Mitotic activity and pleomorphism are usually minimal. The spindle cell population expresses CD31, CD34 and Ulex Europaeus (Am J Ophthalmol 1980;89:546). The so-called "promontory sign", a feature that is not specific to KS, refers to the proliferation of irregular, jagged vascular channels which partly surrounds a pre-existing vessel, resembling a promontory.

In this case, the morphologic and immunophenotypic features were classic. Ki-67 revealed 40-50% reactivity. The tumor expressed HHV8, which is uniquely associated with Kaposi sarcoma (in contrast to other vascular sarcomas). The resection margins were tumor negative.

The histologic differential diagnosis is broad and includes other vascular lesions such as microvenular hemangioma, tufted angioma, targetoid hemosiderotic (hobnail) hemangioma, cavernous hemangioma and pyogenic granuloma (McKee's Pathology of the Skin, 2011). Bacillary angiomatosos may resemble nodular KS, as may some fibrohistiocytic tumors such as variants of fibrous histiocytoma and dermal fasciitis. When considering KS as a possibility, positive HHV8 IHC will confirm this diagnosis.

KS has a variable course. Some patients develop only a few minor skin lesions while others have much more extensive external and internal disease. The latter lesions may result in fatal complications, e.g., from bleeding, obstruction or perforation of an organ (J Am Acad Dermatol 2008;59:179). One study of 20 patients with ophthalmic, AIDS-related Kaposi sarcoma found that most lesions were slowly progressive and responded to systemic drug therapy. For local treatment of ophthalmic Kaposi sarcoma, irradiation appears to be safe and effective for palliative therapy (Arch Ophthalmol 1989;107:858).


Discussion by Dr. Jennifer R. Kaley, University of Arkansas for Medical Sciences (USA).