Thrombocytopenia with multiple splenic lesions - histiocytic sarcoma of the spleen without splenomegaly: A case report.

Background Histiocytic sarcoma (HS) of the spleen is reported to be a rare and lethal disease. The clinicopathological features of splenic HS have not been well described. The objective of this paper is to describe the diagnosis and treatment of a case of this rare disease and provide a review of the literature. Case summary In this article, we discuss the case of a 40-year-old Hispanic female who presented with progressive thrombocytopenia and multiple hypoechoic lesions in the spleen without splenomegaly. Positron emission tomography-computed tomography showed increased activity in cervical lymph nodes, as well as multiple bone and splenic lesions with positive uptake. Two bone marrow biopsies and fine-needle aspiration of the cervical lymph node were inconclusive. Laparoscopic splenectomy was performed, and gross examination showed a 110.1 g spleen with multiple rubbery, nodular lesions within the subcapsular sinus and splenic parenchyma. The microscopic findings showed multinodular histiocyte proliferation with atypia and multilobulated nuclei, which were positive for CD163, CD4, and CD68 by immunohistochemical analysis. The final pathologic diagnosis was difficult and was found to be low-grade HS of the spleen, after consultations with two renowned hematopathology institutions. At the patient\u0027s five-month follow-up visit, her bone marrow metastasis had progressed. She is waiting to be enrolled in a clinical trial. Conclusion Pathologic diagnosis of splenic HS can be challenging. Low-grade differentiation may be associated with a slow progressive disease.