Dermatology MCQ - Viral Infections - Human herpesvirus 8 infection

A 60-year-old man with HIV (CD4 count 120 cells/µL) presents with multiple violaceous, nodular plaques on his lower extremities and trunk. Some lesions are confluent and show minimal scaling. A biopsy reveals a proliferation of spindle-shaped cells forming slit-like vascular spaces, with extravasated red blood cells and hemosiderin deposition. Which of the following is the most likely diagnosis and the associated viral pathogen?

A) Bacillary angiomatosis; Bartonella henselae
B) Kaposi sarcoma; human herpesvirus 8 (HHV-8)
C) Angiosarcoma; no viral association
D) Dermatofibrosarcoma protuberans; no viral association
E) Pyogenic granuloma; no viral association

Correct Answer: B) Kaposi sarcoma; human herpesvirus 8 (HHV-8)

Explanation

This presentation is classic for Kaposi sarcoma (KS), a vascular tumor associated with human herpesvirus 8 (HHV-8) infection.

Key Clinical Features of Kaposi Sarcoma:

• Appearance: Violaceous, brown, or pink nodules or plaques that may be confluent. Lesions often appear on the lower extremities, face, and mucosa (oral, gastrointestinal).

• Settings:

  • Epidemic KS: In HIV/AIDS patients (as in this case), often with CD4 count <200 cells/µL.

  • Classic KS: Older men of Mediterranean or Eastern European descent.

  • Endemic KS: In sub-Saharan Africa.

  • Iatrogenic KS: In immunosuppressed organ transplant recipients.

• Progression: Lesions may ulcerate, cause lymphedema, or involve internal organs (e.g., lungs, GI tract).

Histopathology:

• Spindle-shaped cells forming irregular, slit-like vascular spaces.

• Extravasated red blood cells and hemosiderin deposition (due to chronic hemorrhage).

• Positive for HHV-8 by immunohistochemistry (LNA-1 stain) or PCR.

Why Not the Other Options?

• (A) Bacillary angiomatosis: Caused by Bartonella henselae or B. quintana. Presents as red, friable papules or nodules that may resemble KS but show neutrophilic infiltrates with granular material (clumps of bacteria) on histology. Warthin-Starry stain reveals bacilli.

• (C) Angiosarcoma: A malignant vascular tumor often on the scalp or face of elderly patients. Histology shows atypical endothelial cells forming anastomosing channels, but no HHV-8 association.

• (D) Dermatofibrosarcoma protuberans (DFSP): A fibrohistiocytic tumor with CD34+ spindle cells in a storiform pattern, not vascular spaces or HHV-8 association.

• (E) Pyogenic granuloma: A benign vascular lesion often triggered by trauma or pregnancy. Presents as a rapidly growing, pedunculated red papule that bleeds easily. Histology shows lobulated capillaries, not spindle cells or slit-like spaces.

Management:

• Optimize antiretroviral therapy (ART): Immune reconstitution with ART can lead to KS regression.

• Local therapy: For limited disease—radiation, intralesional chemotherapy (vinblastine), or surgical excision.

• Systemic therapy: For widespread or visceral disease—liposomal doxorubicin or paclitaxel.

Prognosis:
Depends on extent of disease and immune status. With ART, survival has improved significantly.

Note: HHV-8 is also associated with primary effusion lymphoma and multicentric Castleman disease.