A 30-year-old man who recently relocated from Kenya to the UK reports increasing tiredness and dark-violet nodules on his chest and upper limbs. On examination, you also see several smaller violaceous patches on his hard palate. He was recently started on valaciclovir for shingles. Which diagnosis best explains his presentation?

A. Oral lichen planus
B. Kaposi-type vascular tumour
C. Adverse drug eruption to valaciclovir
D. Chronic plaque psoriasis
E. Congenital capillary malformation

Table of Contents

Correct Answer: B. Kaposi-type vascular tumour

DETAILED EXPLANATION

This patient presents with multiple raised, purple-to-violaceous lesions on the skin and similar lesions in the mouth. This pattern is highly characteristic of Kaposi’s sarcoma, a vascular tumour linked to human herpesvirus-8 (HHV-8).

Kaposi’s sarcoma is classically associated with immunosuppression, especially HIV infection. Many individuals from certain African regions have a higher prevalence of both HIV and HHV-8 exposure. His recent shingles episode (herpes zoster) in a young adult is another clue pointing towards a weakened immune system, which further increases suspicion for underlying HIV.

Other diagnoses are less convincing:

Oral lichen planus produces white lace-like lesions, not raised purple nodules.
Drug reactions from antivirals usually present as diffuse rashes, not discrete violaceous lesions involving mucosa.
Psoriasis produces red, scaly plaques—not purple lesions—and does not affect oral mucosa in this way.
Capillary malformations / haemangiomas are typically congenital, isolated, and rarely multifocal or oral in adults.

Thus, the constellation of skin + mucosal lesions, colour, and risk factors strongly points to Kaposi’s sarcoma.

CHEAT SHEET (EXAM-FOCUSED)

Kaposi’s Sarcoma (KS)

Cause: HHV-8 infection
Risk groups: HIV/AIDS, organ-transplant immunosuppression, elderly Mediterranean men, endemic African KS
Lesions:
- Purple, red, or brown papules/plaques
- Can occur on skin, oral cavity, GI tract, respiratory tract
Oral involvement: common—palate lesions are a classic clue
Systemic involvement: may cause GI bleeding, pulmonary nodules, pleural effusions
Diagnosis: clinical + biopsy; assess HIV status
Treatment:
- Treat underlying HIV (start ART)
- Local therapy (radiotherapy, excision) if limited
- Chemotherapy for widespread disease

Key Red Flags

Young patient with purple lesions + mucosal involvement
Recent herpes zoster → indicates potential immunocompromise
Consider HIV testing immediately

FLASHCARDS (20 CARDS)

1. Q: What virus is associated with Kaposi’s sarcoma?
A: HHV-8 (Human Herpesvirus 8).

2. Q: What colour are typical Kaposi lesions?
A: Purple/violaceous.

3. Q: In which patients is Kaposi’s sarcoma most common?
A: Individuals with HIV/AIDS or immunosuppression.

4. Q: What mucosal site is commonly affected by Kaposi’s sarcoma?
A: Hard palate.

5. Q: What is a classic sign of underlying immunodeficiency in young adults?
A: Herpes zoster/shingles.

6. Q: What is the initial investigation when KS is suspected?
A: HIV testing + biopsy of lesion.

7. Q: What is the treatment for disseminated Kaposi’s sarcoma?
A: ART + systemic chemotherapy.

8. Q: What organ involvement in KS can cause haemoptysis?
A: Pulmonary involvement.

9. Q: Why does KS appear purple?
A: Vascular tumour with extravasated blood.

10. Q: Is KS infectious?
A: No—the tumour is not infectious, but HHV-8 is transmissible.

11. Q: What type of tumour is Kaposi’s sarcoma?
A: Low-grade vascular tumour.

12. Q: Does psoriasis affect the oral mucosa?
A: Rarely; not typical.

13. Q: What drug reaction resembles KS?
A: None closely; drug rashes are more diffuse.

14. Q: Are haemangiomas common in adults?
A: No—they are usually congenital or childhood lesions.

15. Q: What is the treatment of localised KS?
A: Radiotherapy or surgical excision.

16. Q: What is the hallmark of AIDS-associated KS?
A: Widespread cutaneous and mucosal disease.

17. Q: What is the key differential for purple nodules in the mouth?
A: Kaposi’s sarcoma.

18. Q: What systemic therapy improves KS outcomes in HIV?
A: Antiretroviral therapy.

19. Q: Is HHV-8 found in all KS patients?
A: Yes—necessary for disease.

20. Q: What imaging is used for suspected pulmonary KS?
A: CT chest.

MCQs

MCQ 1

A 33-year-old HIV-positive man presents with purple nodules on his legs and palate. What virus is responsible?
A. EBV
B. HHV-8
C. Parvovirus B19
D. HSV-2
Answer: B

MCQ 2

Which feature most strongly differentiates Kaposi’s sarcoma from psoriasis?
A. Redness
B. Pruritus
C. Oral mucosal involvement
D. Chronicity
Answer: C

MCQ 3

Pulmonary Kaposi’s sarcoma may present with:
A. Chronic diarrhoea
B. Massive haemoptysis
C. Visual loss
D. Haematuria
Answer: B

MCQ 4

Initial management step when Kaposi’s sarcoma is suspected:
A. Start steroids
B. HIV testing
C. Immediate chemotherapy
D. Stop all medications
Answer: B

MCQ 5

Which treatment improves survival in AIDS-related Kaposi’s sarcoma?
A. Antibiotics
B. Antiretroviral therapy
C. High-dose steroids
D. Antifungals
Answer: B

SUMMARY

Kaposi’s sarcoma is a vascular malignancy caused by HHV-8 and is strongly associated with immunosuppression, especially advanced HIV infection. It commonly presents with purple or violaceous papules, plaques, or nodules on the skin and may also involve mucosal surfaces such as the hard palate, which is a classic diagnostic clue. Lesions arise due to abnormal vascular proliferation and may become confluent or ulcerated over time. Systemic involvement can affect the gastrointestinal tract and lungs, where it may cause bleeding or life-threatening haemoptysis. In young adults, herpes zoster can signal underlying immune deficiency and should increase suspicion for HIV when combined with characteristic skin lesions. Diagnosis is clinical but confirmed with biopsy and immediate HIV testing. Management focuses on treating the underlying immunodeficiency, particularly through antiretroviral therapy, which often leads to regression of lesions. Local therapies such as radiotherapy or surgical excision are used for limited disease, whereas disseminated cases may require systemic chemotherapy. KS should be distinguished from psoriasis, haemangiomas, and drug reactions, none of which typically show oral involvement. Recognising its presentation early is crucial because it may be the first sign of unrecognised HIV infection.

Skin lesions