Differential Diagnosis

The patient's symptoms of fan apathy, night sweats, unintentional weight loss, and a history of HIV infection, combined with the presence of diffuse large B cells and irregular nuclei on excisional biopsy of a lymph node, suggest a range of potential diagnoses. These can be categorized as follows:

• Single Most Likely Diagnosis

  • Diffuse Large B-Cell Lymphoma (DLBCL): This is the most common type of non-Hodgkin lymphoma and is known to be aggressive. The patient's HIV status increases the risk for DLBCL, and the symptoms along with the biopsy findings are consistent with this diagnosis.

• Other Likely Diagnoses

  • Other Non-Hodgkin Lymphomas (NHL): While DLBCL is the most common, other types of NHL, such as follicular lymphoma or mantle cell lymphoma, could also present similarly, especially in an immunocompromised patient.
  • Hodgkin Lymphoma: Although less common than NHL in HIV-positive individuals, Hodgkin lymphoma can also present with systemic symptoms and lymphadenopathy.

• Do Not Miss Diagnoses

  • Tuberculosis (TB): Given the patient's HIV status, TB is a critical diagnosis not to miss, as it can cause similar systemic symptoms (night sweats, weight loss) and lymphadenopathy. TB can be particularly aggressive in immunocompromised individuals.
  • Castleman Disease: This rare disorder can cause lymphadenopathy and systemic symptoms similar to lymphoma, especially in HIV-positive patients. It's crucial to distinguish it from lymphoma due to differences in treatment and prognosis.

• Rare Diagnoses

  • Primary Effusion Lymphoma (PEL): A rare and aggressive type of lymphoma that typically occurs in HIV-positive individuals, often presenting with serous effusions without significant lymphadenopathy. While less likely given the lymph node involvement, it remains a consideration in the differential diagnosis of lymphomas in HIV patients.
  • Lymphomatoid Granulomatosis: A rare lymphoproliferative disorder that can mimic lymphoma, often associated with Epstein-Barr virus (EBV) infection, which is more common in immunocompromised patients. It typically involves the lungs but can affect other areas, including lymph nodes.