Abstract
Background : Histiocytic sarcoma (HS) is a rare malignant neoplasm that arises from the lymph nodes, skin or intestinal tract in adults. We report a very rare case of splenic histiocytic sarcoma with the imprint cytological findings.
Case : A woman in her 60’s was found to have a solid splenic mass measuring 5 cm in diameter. Primary splenic malignant lymphoma was suspected, and spelnectomy was performed for diagnosis and treatment. The cut surface showed a well-demarcated brown-black lesion, 4.5 cm in diameter. Imprint cytology revealed large neoplastic cells in loose clusters, with lymphocytes and neutrophils in the background. The majority of cells had abundant foamy cytoplasm with multiple small vacuoles. The nuclei were large and of various shapes with irregular chromatin distribution. Some enlarged cells showed hemophagocytic activity. Histological examination revealed proliferation of large-sized neoplastic cells with abundant foamy cytoplasm and irregular nuclei. Hemophagocytosis was indentified within some enlarged cells. Immunohistochemical examination revealed that the tumor cells were positive for CD68 (PGM1), CD163 and lysozyme. Based on the findings, the tumor was diagnosed as a primary splenic histiocytic sarcoma.
Conclusion : It is necessary to refer to the clinical information and perform immunostaining because of the difficulty in making the diagnosis of histiocytic sarcoma based on the morphological findings alone.
