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 six diagnostic criteria for neurofibromatosis.
This medical sign is named after Frank W. Crowe (July 2, 1919 – April 29, 1987), an American physician who practiced dermatology in Boise, Idaho.
[1] In 1956 Crowe et al. recognised the autosomal dominant heredity of neurofibromatosis and the use of 6 or more café au lait spots to diagnose the condition.
Axillary freckling also occurs in other disease processes that closely resemble NF1, such as Legius syndrome (cafe-au-lait spots, axillary freckling, and macrocephaly without Lisch nodules, neurofibromas or CNS tumors), and, homozygous HNPCC mutations (cafe-au-lait spots, axillary freckling, and cutaneous neurofibromas in the setting of Hereditary Non-Polyposis Colon Cancer, also known as Lynch syndrome; seen with family history of HNPCC and consanguinity).