Kaposi's sarcoma pathology

Introduction

Kaposi sarcoma it is grouped inside vascular variable tumors evil one behavior. the histology It is typically very distinctive. The characteristics change depending on the nature of the injury clinically as you progress from patch to license plate to nodular phase.

Kaposi's sarcoma histology

The low-power view of Kaposi's sarcoma histology is of a cellular dermal nodule (Figure 1). There may be varying degrees of overlap epidermal changes that can range from prominent hyperkeratosis and acanthosis Frank ulceration. The dermal proliferation is composed of a spindle cell proliferation of endothelial cells that form sinuous vascular spaces. These may be rare in patch phase lesions, progressing to fascicles of spindle cells in nodular lesions (Figures 2,3). This fascicular pattern has been compared to schools of fish. Spindle cells infiltrate through collagen, forming slit-shaped spaces, especially towards the periphery of the lesions (Figure 4). Where newly formed vessels project into an existing space, the promontory sign is seen (Figure 5). This is now recognized as non-specific to this condition.

In plaque and nodular stage lesions, there may be visible intracellular and extracellular hyaline globules, though to represent engulfed erythrocytes. Although rare, this can be seen in patch-stage lesions. They stain PAS positive. While endothelial proliferation is common monomorphic, can be significant nuclear atypia with more mitotic activity (Figure 6). When prominent atypia is seen tumor fits into the category of a anaplastic variant.

the inflammatory the infiltrator is predominantly lymphocytic with scattered plasma Cells are also a clue to this diagnosis. Red blood cells are seen within the slit-shaped spaces and throughout the tumor. Sometimes at the base and periphery of nodular Kaposi, there may be large cavernous vessels.

Histological variants of Kaposi's sarcoma

Numerous pathological variations have been described for Kaposi's sarcoma depending on the nature of the associated additional features or the pattern of dermal proliferation. They are largely intuitive in describing the injury. Reported variants include:

• Anaplastic
• Telangiectatic
• Lymphedematous
• Hyperkeratotic
• Cheloidal
• Micronodular
• Pyogenic granuloma-I like it
• Ecchemotic
• Intravascular

Special tests for Kaposi's sarcoma.

Lesion cells in Kaposi's sarcoma are positive for the non-specific endothelial markers CD31 (Figure 7) and CD34, and also for the lymphatic endothelial marker D2-40 or podoplanin. the antibody a HHV-8 (Human herpes virus 8) latent nuclear antigen 1 is a highly specific commercial stain and has simplified diagnosis in difficult cases. Figure 8.

Differential diagnosis Kaposi's sarcoma

Microvenular hemangioma: This vascular tumor can be difficult to distinguish clinically from early-stage patch lesions. Less well-formed ships, presence of nuclear power. pleomorphism and positive immunohistochemistry HHV-8 is compatible with Kaposi's sarcoma.

Tufted hemangioma: Multiple lobes of spindle cells are seen, but they lack the interlocking pattern of Kaposi's sarcoma or the formation of a slit-shaped vascular channel.

Pseudo-Kaposi's sarcoma (acroangiodermatitis): While in differential from early-stage Kaposi's sarcoma, acroangiodermatitis consists of a regular proliferation of small vessels without the sinuous appearance of Kaposi's sarcoma.

Cavernous hemangioma: This can be considered when there are dilated vessels at the base or periphery of lesions in the nodular stage, but this hemangioma lacks a spindle cell component.

Pyogenic granuloma: Usually only a problem in partial biopsy lesions where only the superficial component of the lesion is demonstrated.