Patients with melanoma, some other rare skin cancers, and some cancers of the penis and scrotum can have their cancer spread to the lymph nodes in the upper part of the leg, called the groin. Medically, this area is called the inguinal area. At present, for melanomas and skin cancers this type of spread is usually found with a special test called a "sentinel lymph node biopsy". This procedure can find spread of even a few cells in a single lymph node—allowing the treating doctor to find the spread very early.