Myiasis secondary to Sermatobia hominis (human botfly) presenting as a long-standing breast mass.

A case of a 54-year-old woman who presented with a breast mass is reported. Histologically, a chronic granulomatous inflammatory response was observed. The response was associated with an organism diagnosed as a fly larva, Dermatobia hominis (human botfly). The incidence of myiasis, infestation by fly larvae, presenting as a long-standing breast mass and mimicking a neoplasm is extremely rare, especially in the United States.