plantar pits

Definition of plantar pit
National Cancer Institute

plantar pit

(PLAN-ter ...)
A tiny dent in the skin on the bottom (sole) of the foot. Plantar pits are usually pink or skin-colored and can often be seen more easily after soaking the feet in water. They are often found in people with a rare, inherited condition called basal cell nevus syndrome (BCNS). People with BCNS have a very high risk of developing basal cell skin cancer and are also at risk of developing other types of cancer, including medulloblastoma.

Source: NCI Dictionary of Cancer Terms