Malignant Histiocytosis With PD-L1 Expression-Dramatic Response to Nivolumab

Long-Term Remission with Novel Combined Immune-Targeted Treatment for Histiocytic Sarcoma Accompanied by Follicular Lymphoma: Case Report and Literature Review

Histiocytic sarcoma (HS) is an extremely rare but aggressive hematopoietic malignancy, and the prognosis has been reported to be rather unfavorable with a median overall survival of merely 6 months. We presented a 58-year-old female patient complaining of abdominal pain and fever, who was admitted to our institution in September 2021. Fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) scan showed enlargement of generalized multiple lymph nodes. Subsequently, laparoscopic retroperitoneal lesion biopsy and bone marrow aspiration were performed. The pathological findings indicated the diagnosis of HS concurrent with follicular lymphoma. The immunohistochemistry (IHC) staining of the tumor lesion revealed a high expression of CD38 and PD-L1 proteins. Furthermore, KRAS gene mutation was identified by means of next-generation sequencing. The patient exhibited poor treatment response to both first- and second-line cytotoxic chemotherapies. Therefore, she underwent six cycles of Daratumumab (anti-CD38 monoclonal antibody), Pazopanib (multi-target receptor tyrosine kinases inhibitor) combined with third-line chemotherapy, followed by involved-site radiotherapy and maintenance therapy with the PD-1 inhibitor Tislelizumab. Long-term partial remission was finally achieved after multi-modality treatment. Duration of remission and overall survival reached 22 and 32 months, respectively. Our case indicated that immuno-targeted treatment coupled with chemotherapy and radiotherapy might constitute a potential therapeutic option for HS.

Histiocytic Sarcoma Treated with Pembrolizumab: A Case Report and Literature Review

Histiocytic sarcoma (HS) is a rare hematologic malignancy that has historically been treated with lymphoma-based regimens with a median survival of 6 months. We describe a case of a 51-year-old woman who presented with acute back pain and cord compression. She was diagnosed with HS with diffuse skeletal lesions and high expression of programmed death ligand 1 (PD-L1). She was subsequently treated with chemotherapy plus off-label use of pembrolizumab followed by allogeneic stem cell transplantation. Ultimately, the patient died in the setting of progression of disease 17 months after her stem cell transplantation and 26 months after her diagnosis. This article also presents a literature review of cases of HS treated with programmed death ligand inhibition.