It's important to have a thorough evaluation by a dermatologist to determine the cause of the black spot on your leg. While topical treatments like steroid and hydroquinone creams can be effective for certain conditions, they may not work for all types of pigmentation or lesions. Some possible causes of dark spots include post-inflammatory hyperpigmentation, melasma, or even benign lesions like seborrheic keratosis. In some cases, procedures such as laser therapy, chemical peels, or cryotherapy might be more effective. I recommend scheduling an appointment with a board-certified dermatologist who can provide a proper diagnosis and tailored treatment plan.