Severe lactic acidosis in association with CD5+ large B-cell lymphoma

Lactic acidosis is classified into type A and type B. In cases of type B lactic acidosis, it is important to consider underlying lymphomas, mostly B-cell types, such as intravascular large B-cell lymphoma (IVLBCL) or diffuse large B-cell lymphoma. Cluster of differentiation (CD) 5+ large B-cell lymphoma (LBCL) is well-known for its aggressive nature. We report here two cases of CD5+ LBCL that showed severe lactic acidosis (11.2 mmol/L and 15.9 mmol/L, respectively; reference range: 0.6–1.7) with hypoglycemia. Case 1 was a 79-year-old female who presented with multiple organ failure. CD5+ IVLBCL was diagnosed through a random skin biopsy in this patient. Case 2 was a 78-year-old female with bone marrow involvement by CD5+ LBCL cells and liver failure. The patient was also diagnosed pathologically as IVLBCL by liver biopsy. Both patients were under ventilator management and high-flow continuous hemodialysis and filtration. Plasma exchange was also employed. An anti-lymphoma regimen (a 50% dose-reduced etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab) was introduced on day 11 and day 2 of hospitalization for cases 1 and 2, respectively. In Case 1, lactic acidosis was normalized within day 17, and the patient survived longer than 8 weeks, while in Case 2, lactic levels did not improve until her death on day 16 of hospitalization. In conclusion, prompt recognition of type B lactic acidosis and early diagnostic biopsy are essential for improving outcomes in aggressive CD5+ IVLBCL, highlighting the need for novel therapeutic strategies.