Answer: tungiasis, due to the "chigoe" flea, Tunga penetrans
Arthur V gave us a great description, pointing out the trachae (T), eggs, and striated muscle (M). A portion of the stratum corneum of the epidermis (E) can also be seen. The cuticle of the flea lies right below this.
Tunga penetrans female fleas embed in the epidemis where they feed and produce eggs. The posterior of the flea sticks out from the skin, allowing the eggs to be released (if you squeeze the lesion, you may be able to express the eggs). Humans usually become infected by walking barefoot on the beach in tropical and subtropical areas. Therefore, the history of this case (walking barefoot on the beach in Brazil) is classic.