Alternative names 
Arachnodactyly; Spider fingers; Achromacria

Arachnodactyly is a physical condition in which the fingers are long, slender, and curved, resembling a spider’s legs.


Long, slender fingers can be a normal variation, not associated with any medical problems. However, in some cases, the tendency to develop spider fingers can indicate an underlying hereditary disorder.

Common Causes

  • normal finding  
  • Marfan’s syndrome  
  • homocystinuria  
  • spondylocostal dysostosis

Call your health care provider if

Some children are born with arachnodactyly, although it may develop over time. Consult with your health care provider during a routine examination if your child has long, slender fingers and you are concerned that an underlying condition may exist.

What to expect at your health care provider’s office

The medical history will be obtained and a physical examination performed.

Medical history questions documenting arachnodactyly in detail may include:

  • time pattern       o When did you first notice the fingers being shaped like this?  
  • family history       o Is there any family history of early death?       o Is there any family history of known hereditary disorders?  
  • other       o What other symptoms are also present?       o Have you noticed any other unusual things?

The physical examination may include thorough inspection for other indications that a hereditary disorder may be present. Diagnostic tests are usually not necessary unless a hereditary disorder is suspected.

Johns Hopkins patient information

Last revised: December 3, 2012
by Gevorg A. Poghosian, Ph.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.