Ainhum (from Portuguese, pronounced īn-yoom´, i´num or ān´hum; also known as dactylolysis spontanea) is a painful constriction of the base of the fifth toe frequently followed by bilateral spontaneous autoamputation a few years later.
Signs and symptoms
The groove begins on the lower and internal side of the base of the fifth toe, usually according to the plantar-digital fold. [Source: Wikipedia 
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