What can this be? I've had 4 laser hair removal sessions and after session 2 this bump appeared. (photo)

this is likely a dermatofibroma, i suggest seeing a cosmetic dermatologist for an evaluation.  Best, Dr. Emer.

Your photo appears to show a benign lesion called a dermatofibroma. It is a common benign fibrous nodule that most often arises on the skin of the lower extremity. They are more common in women than in men.

It is not clear if dermatofibroma is a reactive process or if it is a neoplasm. The lesions are made up of a proliferation of fibroblasts (skin cells responsible for producing collagen, among other things).

They are sometimes attributed to an insect bite. It is not likely that this is relaTed to the laser hair removal, in other words it is a coincidence.If bothersome they can be excised, they generally do not go away on their own.Best,Lisa Vuich, MD