Background <p>Testicular tumors are relatively uncommon urogenital malignancies, accounting for only 1–2% of all cancers in men, with germ cell tumors representing the predominant histopathological subtype. Histiocytic sarcoma (HS) is a rare and aggressive malignancy that typically arises in extranodal sites, and its standard treatment strategy has yet to be established. Here, we report a rare case of testicular histiocytic sarcoma, which has been sparsely documented in previous studies and for which clinical experience remains limited, thereby providing valuable insights into its diagnostic challenges and clinical management.</p> Case presentation <p>This case describes a 70-year-old male admitted with enlarged left scrotum accompanied by ulceration. Based on the chief complaint, medical history, physical examination and ancillary investigation results, enhanced CT and MRI revealed patchy mixed-density shadows in the left testicular region and with obvious enhancement, which indicated the possibility of neoplastic lesion. The patient had indications for surgery and underwent orchiectomy. Histopathological and immunohistochemical evaluation confirmed a testicular histiocytic sarcoma. The postoperative recovery was uneventful and the follow-up data revealed no recurrence.</p> Conclusion <p>Testicular histiocytic sarcoma is an uncommon type of tumor that has rarely been reported before. Its diagnosis remains challenging and the standard treatment for this disease is still undetermined. This case could provide valuable clinical experience and contribute to a more comprehensive understanding of testicular histiocytic sarcoma, and indicated surgical resection might be a feasible treatment for selected cases.</p>