放線菌症 (actinomycosis) 是一種慢性的化膿性和肉芽腫性傳染病，可能為局部或全身性。其致病菌是屬於革蘭氏陽性、非抗酸性、厭氣性兼微好氣菌，是口腔中的正常菌叢。臨床上最常感染之部位為頸面部、胸部，腹部和骨盆腔。原發性肢體放線菌症在臨床上並不多見，其臨床表現與一般細菌感染雷同因而容易被忽略。此報告病例為一位65歲男性，為右下肢反覆性化膿性傷口所困擾。經外科手術切除，病理報告證實為放線菌病。可能的感染來源為病患習慣性的使用口水塗抹傷口，將口腔內放線菌帶至傷口所致。

Primary cutaneous actinomycosis of the extremity is very uncommon and can easily be regarded asordinary soft tissue infection. Herein, a case of 65-year-old man with primary cutaneous actinomycosis athis lower extremity, probably after direct inoculation of the microorganism from his saliva into a precedingwound in extremity, was reported. He was treated successfully with surgical excision combined withextended period of antimicrobial treatment.