After the lesion of primary yaws heals, a generalized eruption of soft granulomata on the face, extremities (top), or buttocks occurs. Another feature of secondary yaws is soft, keratotic, tumor-like masses that develop on the soles of the feet (bottom). The masses force patients to walk on the sides of their feet, giving rise to the nickname crab yaws.
Top image courtesy of Dr. Peter Perine via the Public Health Image Library of the Centers for Disease Control and Prevention. Bottom image courtesy of Dr. Susan Lindsley via the Public Health Image Library of the Centers for Disease Control and Prevention.