eccrine porocarcinoma is a rare type of skin cancer originating from eccrine sweat glands or acrosyringium , representing 0.01% of all cutaneous tumors . since it mainly occurs in the elderly [ 1 , 2 ] , such patients may possess a high risk of perioperative complications and , in such cases , radical surgical treatment is not practical . in this report , we describe a case of recurrent eccrine porocarcinoma that metastasized to a cervical lymph node successfully treated with cyberknife . an 85-year - old woman consulted us with a 3-month history of a red nodule . on her initial visit , physical examination revealed a red , easy - to - bleed , dome - shaped nodule 20 mm in diameter on her right cheek ( fig . dermoscopy findings revealed irregular arborizing vessels , and whitish globular structures covered by prominent bleeding ( fig . skin biopsy revealed dense infiltration of clear , cuboidal , basaloid atypical cells throughout the dermis ( fig . immunohistochemical staining revealed that these tumor cells were positive for cea , 34be12 , p63 , ck5/6 and ck14 , and negative for gcdfp15 . from these results , we diagnosed this case as eccrine porocarcinoma . we screened for a possible internal malignancy with positron emission tomography - computed tomography , which revealed significant enlargement of the cervical lymph nodes ( fig . 3a ) . as the lesion was adjacent to the external carotid artery and standard surgical therapy would have been impractical , we employed a cyberknife . the lesion of the cervical lymph node was irradiated with 50 gy in 10 fractions . one month after the irradiation , the tumor mass had completely regressed , leaving a scar ( fig . 3b ) . there was no severe side effect such as radiation dermatitis at the site of the irradiated lesion . in this report , we describe a case of recurrent eccrine porocarcinoma that metastasized to a cervical lymph node successfully treated with cyberknife . porocarcinoma is described as a biologically aggressive neoplasm that frequently metastasizes to regional lymph nodes [ 1 , 2 ] . indeed , robson et al . the representative standard therapy for lymph node metastasis is regional lymphadenectomy , but its mortality rate is high [ 1 , 2 , 3 ] . in addition , since patients with porocarcinoma tend to be elderly , they may have a high risk of perioperative complications . indeed , in our present case , since the lesion was located near critical facial structures and the patient was very old , radical surgical treatment such as cervical lymphadenectomy was not practical . in addition , conventional radiotherapy sometimes induces severe side effects after intensive treatment , and generally has been reported to be of little benefit in both primary and metastatic porocarcinoma , but has mostly been used as a palliative treatment . for these reasons , we selected cyberknife . cyberknife is a robotic image - guided stereotactic radiosurgery device that delivers a large ablative radiation dose to the tumor while sparing normal surrounding tissue . we previously reported successful treatment of a dermatofibrosarcoma protuberance and merkel cell carcinoma using cyberknife [ 5 , 6 ] . as we previously reported [ 5 , 6 ] , this system is able to deliver extracranial stereotactic radiotherapy with millimetric precision , leading to disease control and toxicity profiles that are equal to or better than other available therapies . to our knowledge , there is no english language report of metastatic porocarcinoma treated with cyberknife without significant side effects . our present study suggests the novel possibility of using cyberknife for the treatment of inoperable metastatic porocarcinoma . since porocarcinoma tends to recur both in local and remote areas long after the treatment and our follow - up period is short , further follow - up is needed for a definitive conclusion .
eccrine porocarcinoma is a rare type of skin cancer that originates from eccrine sweat glands or acrosyringium and mainly occurs in the elderly . in this report 
 , we describe an 85-year - old japanese woman with eccrine porocarcinoma that metastasized to a cervical lymph node who was cured with cyberknife radiosurgery . because our patient had a high risk of perioperative complication , standard surgical therapy with a wide margin was impractical . 
 our present study suggests the novel possibility of using cyberknife for the treatment of inoperable metastatic porocarcinoma .