Leiomyoma is a generally benign tumour and common in the uterine smooth muscle. In some cases, it is found in other parts of the human body. In our study, we report the case of a 61-year-old woman with a painless cystic lesion on the first left thumb associated with trigger finger. The first diagnostic hypotheses were ganglionic cyst and giant cell tumour, however, after surgical excision and histological analysis, it was revealed to be a rare leiomyoma of the hand. We report a clinical case and detailed histopathological study, with 12 high-resolution images stained with: H&E, Smooth Muscle Actin, Desmin, S-100 and CD34.