Fatal hemophagocytic lymphohistiocytosis with intravascular large B-cell lymphoma following coronavirus disease 2019 vaccination in a patient with systemic lupus erythematosus: an intertwined case

Hemophagocytic lymphohistiocytosis (HLH) has been recognized as a rare adverse event following the coronavirus disease 2019 (COVID-19) vaccination. We report a case of neuropsychiatric symptoms and refractory HLH in a woman with systemic lupus erythematosus (SLE) after receiving her COVID-19 vaccine treated with belimumab, later found to have intravascular large B-cell lymphoma (IVLBCL) at autopsy. A 61-year-old woman with SLE was referred to our hospital because of impaired consciousness and fever. One month prior to consulting, she received her second COVID-19 vaccine dose. Afterward, her consciousness level decreased, and she developed a high fever. She tested negative for SARS-CoV-2. Neuropsychiatric SLE was suspected; therefore, glucocorticoid pulse therapy was initiated on day 1 and 8. She had thrombocytopenia, increased serum ferritin levels and hemophagocytosis. The patient was diagnosed with HLH and treated with etoposide, dexamethasone and cyclosporine. Despite treatment, the patient died on day 75; autopsy report findings suggested IVLBCL as the underlying cause of HLH. Differentiating comorbid conditions remains difficult; however, in the case of an atypical clinical presentation, other causes should be considered. Therefore, we speculate that the COVID-19 vaccination and her autoimmune condition may have expedited IVLBCL development.

Osteosarcoma Manifesting Systemic Inflammation and Histological Features Mimicking Plasma Cell-type Castleman Disease

A 73-year-old man was referred to our hospital with a persistent fever, anemia, and a mass in the left pubic region. The findings of biopsy evaluations of the mass and a left inguinal lymph node were consistent with Castleman disease (CD) of plasma cell type. His serum interleukin 6 (IL-6) level was remarkably elevated, supporting the diagnosis of CD. However, imaging analyses revealed destruction of the pubic bone by the mass, which was atypical for CD. Therefore, another deeper biopsy was performed, which finally led to the diagnosis of IL-6-producing osteosarcoma. We conclude that clinicians should carefully exclude malignancies prior to making a CD diagnosis.