Immunology · Year 2 · from Immunology
Case 1: HIV/AIDS with Opportunistic Infections
Patient Demographics
- Age: 34 years old
- Sex: Male
- Ethnicity: African American
Chief Complaint
Fever, cough, and shortness of breath for 2 weeks
History of Present Illness
A 34-year-old man presents with progressive dyspnea on exertion, dry cough, and low-grade fevers for 2 weeks. He has also experienced a 20-pound unintentional weight loss over 3 months and has had white patches in his mouth. He denies any medical history and has not seen a doctor in over 10 years. He reports multiple male sexual partners without consistent condom use.
Past Medical History
- None known
- No prior HIV testing
Social History
- Men who have sex with men (MSM)
- Inconsistent condom use
- No IV drug use
- Works as a restaurant manager
Physical Examination
- General: Thin, ill-appearing man in mild respiratory distress
- Vital Signs: T 38.5C, HR 105, RR 26, BP 110/70, SpO2 88% on room air
- HEENT: Oral thrush coating tongue and palate; hairy leukoplakia on lateral tongue
- Lymphatics: Generalized lymphadenopathy (cervical, axillary, inguinal)
- Lungs: Bilateral dry crackles; increased work of breathing
- Skin: Seborrheic dermatitis; violaceous nodules on lower extremities and hard palate
Laboratory Workup
| Test | Result | Reference Range |
|---|---|---|
| WBC | 3,200/uL | 4,500-11,000/uL |
| Absolute lymphocyte count | 450/uL | 1,000-4,800/uL |
| Hemoglobin | 10.5 g/dL | 14-18 g/dL |
| HIV-1/2 Ag/Ab | Reactive | Non-reactive |
| HIV-1 RNA viral load | 450,000 copies/mL | Undetectable |
| CD4 count | 45 cells/uL | 500-1500 cells/uL |
| CD4 percentage | 4% | 30-60% |
| LDH | 850 U/L | 140-280 U/L |
| Beta-D-glucan | Positive | Negative |
| CXR | Bilateral diffuse interstitial infiltrates | Normal |
| BAL | Pneumocystis jirovecii (DFA positive) | Negative |
| Skin biopsy | Kaposi sarcoma | -- |
Clinical Image
Image showing bilateral interstitial infiltrates characteristic of Pneumocystis jirovecii pneumonia in AIDS. Image source: Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Pneumocystis_jiroveci_01.jpg). Public domain.
Diagnosis
AIDS (CD4 <200) with Pneumocystis jirovecii pneumonia (PJP) and Kaposi sarcoma in a newly diagnosed HIV infection.
Discussion
HIV infection is the most common cause of secondary (acquired) immunodeficiency worldwide:
HIV pathogenesis:
- HIV primarily infects CD4+ T cells via the CD4 receptor and CCR5/CXCR4 coreceptors
- Progressive CD4+ T cell depletion leads to immunodeficiency
- AIDS is defined by CD4 <200 cells/uL OR an AIDS-defining condition
CD4 count and infection risk:
| CD4 Count | Opportunistic Infections |
|---|---|
| <500 | Oral candidiasis, herpes zoster, bacterial infections |
| <200 | PJP, toxoplasmosis, cryptococcosis |
| <100 | CMV disease, MAC, CNS lymphoma |
| <50 | Disseminated MAC, CMV retinitis |
This patient's presentation:
- PJP: Most common AIDS-defining opportunistic infection; presents with subacute dry cough, dyspnea, and bilateral interstitial infiltrates; elevated LDH and positive beta-D-glucan support diagnosis
- Kaposi sarcoma: Caused by HHV-8; presents as violaceous nodules on skin and mucous membranes; AIDS-defining
- Oral thrush and hairy leukoplakia: Indicate immunosuppression
Prophylaxis guidelines based on CD4:
- CD4 <200: PJP prophylaxis (TMP-SMX first-line)
- CD4 <100: Toxoplasma prophylaxis (TMP-SMX covers both)
- CD4 <50: MAC prophylaxis (azithromycin)
Treatment
- PJP treatment: TMP-SMX high dose for 21 days; add prednisone (PaO2 <70 or A-a gradient >35)
- Start ART: After 2 weeks of PJP treatment to reduce immune reconstitution inflammatory syndrome (IRIS) risk
- Kaposi sarcoma: Will likely improve with ART-induced immune reconstitution; chemotherapy if extensive
- OI prophylaxis: TMP-SMX for PJP and toxoplasmosis prophylaxis
- Counseling: Risk reduction, partner notification