Differential Diagnosis for Membranoproliferative Glomerulonephritis
- Single most likely diagnosis
- C. Hepatitis C virus infection: This is the most likely cause given the patient's history of engaging in transactional sex, which increases the risk of hepatitis C virus (HCV) infection. HCV is a well-known cause of membranoproliferative glomerulonephritis (MPGN), particularly type 1, which is characterized by the deposition of immune complexes and complement components, including IgG, IgM, C1q, and C3, as seen in this patient's kidney biopsy.
- Other Likely diagnoses
- B. Hepatitis B virus infection: Although less commonly associated with MPGN compared to HCV, hepatitis B virus (HBV) infection can also cause this condition, especially in endemic areas or in individuals with high-risk behaviors. However, the patient's negative HIV test and lack of other risk factors make HBV less likely.
- D. Syphilis: Syphilis, particularly secondary syphilis, can cause MPGN. The patient's engagement in transactional sex increases her risk for syphilis. However, syphilis is less commonly associated with MPGN compared to HCV, and other symptoms or signs of syphilis are not mentioned.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- A. Genetic mutations of alternative complement pathway proteins: While rare, genetic mutations affecting the alternative complement pathway (e.g., factor H, factor I, or membrane cofactor protein) can lead to atypical hemolytic uremic syndrome (aHUS) or MPGN. These conditions can have a poor prognosis if not recognized and treated promptly with eculizumab or other complement inhibitors.
- Rare diagnoses
- Systemic lupus erythematosus (SLE): Although the patient has negative antinuclear antibodies, SLE can occasionally present with negative ANA, especially in the early stages. However, the lack of other SLE criteria and the specific pattern of immunofluorescence staining make this diagnosis less likely.
- Other infections or autoimmune disorders: Other infections (e.g., bacterial endocarditis, Lyme disease) or autoimmune disorders (e.g., rheumatoid arthritis, scleroderma) can also cause MPGN, but they are less likely given the patient's presentation and laboratory results.