NR507 Week 1: Underlying Pathophysiological Mechanisms and Clinical Manifestations

Underlying Pathophysiological Mechanisms and Clinical Manifestations

Human Immunodeficiency Virus (HIV) is a retrovirus that attacks T-lymphocytes (CD4) and the macrophages and dendritic cells, which are the most important in adaptative immunity. The virus attaches to the CD4 receptors and co-receptors (CCR5 or CXCR4) of host cells leading to entry. The infection damages the CD4+ T-cells by replicating upon entry, infecting cells by reverse-transcribing HIV RNA into DNA and inserting it into the host genome (Olebo, 2025).

The loss compromises the cell mediated immunity causing opportunistic infections and malignancy. With time, the chronic immune activation and inflammation continue despite the antiretroviral therapy, and they are associated with the end-organ damage.

The clinical manifestations of Wilbur are in line with high-level HIV (AIDS). The purple, flat, rash indicates Kaposi sarcoma (KS), a cancer that is a result of human herpesvirus-8 (HHV-8), which grows in immunocompromised patients (Cesarman et al., 2019). KS lesions are non-painful, non-pruritic and located on mucocutaneous surfaces. The mucous layer on the tongue is probably white tongue coating, which a fungi infection is caused by the suppression of Th17-mediated mucosal immunity.

The frequent occurrence of illnesses in him (been sick a lot) is indicative of opportunistic infections (e.g., pneumocystis pneumonia, recurrent bacterial infections) due to depletion of CD4+ T-cells. All these findings demonstrate the pathophysiology of HIV in general immune dysfunction which allows infections and cancers.

Analysis of Wilbur’s Clinical Manifestations

The symptoms of Wilbur are very strong in favor of advanced HIV. Kaposi sarcoma is an AIDS-defining disease, and it almost always happens when the counts of CD4+ decrease to below 500 cells/mm3. Another AIDS indicator is oral candidiasis which is a reflection of failure in mucosal immunity. Repeat infections indicate severe dysfunction of the immune system. Although non-HIV illnesses (e.g. primary immunodeficiency, hematologic malignancies) might lead to similar symptoms, presence of KS, thrush and frequent infections are pathognomonic of AIDS.

It is important to agree that rashes related to HIV (e.g., KS, drug reactions) contrast with autoimmune or allergic rashes, which are usually pruritic or inflammatory (Gorecka et al., 2024). Wilbur rash chronicity (months) and lack of itching also represent another difference between KS and acute viral exanthems. So, his presentation significantly coincides with untreated AIDS developing out of HIV.

Diagnostic Tests for HIV and Anticipated Results

Key diagnostic tests include:

• Fourth-generation HIV-1/2 antigen/ antibody immunoassay: Antibodies and HIV p24 antigen (viral core protein) are detected. A positive outcome requires confirmation using a differentiation immunoassay in order to differentiate HIV-1 and HIV-2.
• HIV-1 RNA PCR (viral load): Measures the viral replication; high level ( > 100,000 copies/mL) is an indication of active or untreated HIV (Jagodzinski et al., 2020).
• CD4+ T-cell: It should be less than 200 cells/mm3 in AIDS.
• Oral thrush testing: Oral potassium hydroxide (KOH) preparation of tongue scrapings would help to identify pseudohyphae, which would be an indication of candidiasis.
• Kaposi sarcoma biopsy Histopathology reveals spindle cells, erythrocyte extravasation, and HHV-8.
• Screening of opportunistic infections: Chest X-ray (in case of pneumocystis) and serologic examination of CMV, toxoplasmosis or tuberculosis.

Among the expected outcomes are positive HIV serology, elevated viral load, decreased CD4+ lymphocytes, and KS biopsy. The results would affirm that HIV is the cause of the symptoms experienced by Wilbur.

Comparison with SLE

            The peer suggesting systemic lupus erythematosus (SLE) may inform that the rash, frequent infections Wilbur presented with, may be consistent with the autoimmune processes, but the classic SLE symptoms (photosensitive malar rash, arthralgia, systemic inflammation e.g., nephritis, serositivity) are not present in his case. Rashes caused by SLE are erythematous, vascular and sun induced, contrary to non-pruritic and flat purple lesions typically seen on Wilbur, which resemble those of Kaposi sarcoma. 

Although SLE may predispose infection in the case of immunosuppressive treatments, Wilbur has frequent infections, which are probably caused by the depletion of CD4+ T-cells and opportunistic pathogens, which are inconsistent with the pathophysiology of SLE. A positive response in the absence of autoantibodies (e.g., anti-dsDNA), complement (e.g., abnormalities in complement), or multi-organ (e.g. multi-component) involvement further undermines the SLE hypothesis, and makes HIV/AIDS the more likely explanation of his clinical picture.

For week 8 assignment of this class: NR507 Week 8 Assignment