Background Primary testicular leiomyosarcoma has a rare occurrence and the diagnosis is uncertain on pre-operative assessment. It is often seen in the background of chronic inflammation, radiotherapy, and the use of high-dose anabolic steroids. Case presentation We report a case of a painless testicular lump in a septuagenarian with pre-existing diabetes mellitus and hypertension but without any oncological risk factors. The primary workup did not reveal any elevation of serum tumour markers or any signs of metastatic disease on contrast imaging. The patient underwent a high inguinal orchiectomy due to a suspicion of germ cell tumor, and histopathology and immunohistochemistry confirmed the diagnosis of leiomyosarcoma. Conclusion Testicular leiomyosarcoma in the elderly is a rare malignancy and usually occur without any pre-existing risk factors. Early treatment provides long-term curative oncological control.