La d A 50-year-old HIV patient presented with a painless lesion, as shown in the image. La d What is the most likely diagnosis?

Correct Answer: D. Kaposi sarcoma

Kaposi sarcoma (KS) is the most common malignancy in HIV-positive patients, particularly when CD4+ count falls below 50 cells/μL. It is caused by Human Herpesvirus 8 (HHV-8), also known as Kaposi sarcoma-associated herpesvirus (KSHV). The clinical presentation of a painless, violaceous (purple-red) lesion in an HIV patient is pathognomonic for KS. The lesion typically appears as a macule, papule, or plaque with a characteristic dark purple or brown color due to neovascularization and hemosiderin deposition. In India, KS incidence in HIV patients has increased significantly with improved ART access but delayed diagnosis in advanced disease. The diagnosis is confirmed by histopathology showing spindle cell proliferation with slit-like vascular spaces. Early recognition is critical because KS can involve multiple organ systems (oral cavity, GI tract, lungs) and requires prompt initiation of antiretroviral therapy (ART) as first-line management, often combined with chemotherapy (liposomal doxorubicin) in advanced cases. The painless nature and characteristic color distinguish it from other cutaneous malignancies in this immunocompromised setting.

Why the other options are wrong

A. Basal cell carcinoma — BCC typically presents as a pearly nodule with central ulceration ('rodent ulcer') and rolled edges, often with telangiectasia. It is not associated with HIV immunosuppression and occurs predominantly in sun-exposed areas in elderly patients. The painless violaceous lesion in an HIV patient is not characteristic of BCC, which usually appears flesh-colored or translucent, not purple-red. B. Squamous cell carcinoma — SCC presents as a scaly, erythematous nodule or ulcer with a hyperkeratotic surface, often with a history of actinic keratosis or chronic sun exposure. While SCC incidence may increase in HIV patients, it lacks the characteristic violaceous color and vascular appearance of KS. SCC is not the most common HIV-associated malignancy and typically affects sun-exposed areas in older patients. C. Malignant melanoma — Melanoma presents with the ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving). While melanoma can occur in HIV patients, it is not the most common HIV-associated cutaneous malignancy. The clinical presentation and epidemiology strongly favor KS over melanoma in an HIV patient with a painless violaceous lesion. Melanoma typically shows more color heterogeneity and irregular borders.

High-Yield Facts

Mnemonics

KS in HIV: The 'Purple Flag' Rule Purple lesion + HIV + Painless = KS. Remember: violaceous color is the visual clue; painless distinguishes it from inflammatory conditions. HHV-8 & KS: 'KSHV Needs CD4 Below 50' Kaposi Sarcoma Herpesvirus Viral reactivation occurs when CD4 <50 cells/μL. This is the critical threshold for clinical KS manifestation in HIV patients.

NBE Trap

NBE may pair "painless lesion in HIV" with common cutaneous malignancies (BCC, SCC, melanoma) to test whether students recognize that KS is the most common HIV-associated malignancy and its pathognomonic violaceous appearance, not just any painless skin lesion in an immunocompromised patient.

Clinical Pearl

In Indian HIV clinics, KS remains a common AIDS-defining illness in patients presenting late with CD4+ <50 cells/μL. Early recognition and immediate ART initiation can lead to complete regression of KS lesions within weeks, making it one of the most rewarding diagnoses to catch early in HIV management.

_Reference: Harrison Ch. 197 (HIV/AIDS); Robbins Ch. 7 (Neoplasia & Immunodeficiency); KD Tripathi Ch. 57 (Antiretroviral agents)_