1404
OBJECTIVE : The purpose of this study was to report the concomitant occurrence of multiple squamous cell carcinomas and diffuse nail hyperpigmentation associated with hydroxyurea treatment , and to describe a successful therapeutic approach using imiquimod 5 % .
 diffuse nail hyperpigmentation, hydroxyurea; multiple squamous cell carcinomas, hydroxyurea
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 diffuse nail hyperpigmentation, hydroxyurea; multiple squamous cell carcinomas, hydroxyurea