Differential Diagnosis
- Single most likely diagnosis:
- Chronic Lymphocytic Leukemia (CLL) - The presence of an abnormal B cell population expressing CD19, CD20, and lambda light chain restriction, but lacking CD5, is atypical for CLL. However, the low forward and side scatter and the specific immunophenotypic profile (positive for CD45, CD19, CD20, and lambda, but negative for CD5, CD10, CD38, CD25, CD103, CD11c, and kappa) could still suggest a variant of CLL or another lymphoproliferative disorder. The absence of CD5 is unusual but can be seen in some cases of CLL.
- Other Likely diagnoses:
- Mantle Cell Lymphoma (MCL) - Although MCL typically expresses CD5, there are rare cases that may lack CD5 expression. The lambda light chain restriction and the presence of an abnormal B cell population could suggest MCL, especially if there's a history of lymphadenopathy or other systemic symptoms.
- Follicular Lymphoma (FL) - The expression of CD19 and CD20 along with lambda light chain restriction could be seen in FL. However, FL typically expresses CD10, which is negative in this case.
- Marginal Zone Lymphoma (MZL) - MZL can have a varied immunophenotype but often lacks CD5 and CD10, which fits this profile. The lambda light chain restriction also supports this diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Hairy Cell Leukemia (HCL) - Although the immunophenotype provided (negative for CD25, CD103, and CD11c) does not strongly support HCL, this diagnosis should be considered due to its specific treatment requirements and potential for severe infections if left untreated.
- Large Cell Lymphoma - Given the presence of an abnormal B cell population, it's crucial to rule out more aggressive lymphomas, even though the provided immunophenotype does not directly suggest large cell lymphoma.
- Rare diagnoses:
- Lymphoplasmacytic Lymphoma (LPL) - This diagnosis could be considered, especially if there's an increase in plasma cells, but the provided information does not strongly support LPL.
- Burkitt Lymphoma/Leukemia - Typically expresses CD10 and has a different clinical presentation, making it less likely but not impossible, especially in the absence of specific genetic information (e.g., MYC rearrangement).