The Crowe sign or Crowe's sign is the presence of axillary (armpit) freckling in people with neurofibromatosis type I (von Recklinghausen's disease). These freckles occur in up to 30% of people with the disease and their presence is one of seven diagnostic criteria for neurofibromatosis. Freckles can also be present in the inguinal (groin) area in neurofibromatosis.
This medical sign is named after Frank W. Crowe, an American physician. He noticed that axillary freckles are present in about 20-30% of patients with neurofibromatosis, but he did not see any in patients who did not have neurofibromatosis.