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caucasian and caribbean men have a higher incidence of prostate cancer than men in asia .
prostate cancer remains the second leading cause of cancer death in men after lung cancer .
the incidence of latent prostate cancer observed at autopsy and the incidence and prevalence of clinically manifest prostate cancer increase substantially with age .
the most common sites of metastasis are the bones and regional lymph nodes , followed by the liver , lungs , brain , and digestive system .
lymphatic dissemination occurs most often in regional lymph nodes such as the obturator , internal , and external iliac lymph nodes , followed by presacral and para - aortic lymph nodes .
usually , neck lymphadenopathies are encountered in head and neck mucosal or skin squamous cell carcinomas or melanoma as well as in malignant lymphomas .
systemic neck metastases have been described in the lungs , stomach , kidneys , and testicles . to the authors knowledge , only few cases of neck metastases from prostatic adenocarcinoma have been reported . in this article
we report a very uncommon case of the concomitant occurrence of a prostatic adenocarcinoma with neck metastases ( ct3 g2 cn0 cm1 ) and an advanced laryngeal squamous cell carcinoma without neck metastases ( pt4a g2 pn0 cmx r0 ) .
in august 2011 , a 67-year - old swiss man was admitted to the head and neck surgery department due to dysphonia and airway aspiration , with recent progressive dyspnea .
the patient was also known for a metastatic prostate cancer ( ct3 g2 cn0 cm1 ) since 2004 , which had been treated with hormonotherapy and orchidectomy . physical examination ( panendoscopy ) showed a very large obstructive tumor infiltrating and fixing the 3 levels of the right larynx .
no cervical adenopathy was found clinically . on the diagnostic ct scan , a 5-cm mass of the right vocal cord with osteolysis of the thyroid and arytenoid cartilage and invasion of the surrounding muscles was noted .
after a multidisciplinary discussion , the patient was treated by a total laryngectomy and bilateral supraselective neck dissection .
the histological analysis showed a moderately differentiated squamous cell carcinoma of the larynx , infiltrating the right cricoid and thyroid cartilages and extralaryngeal soft tissues .
of the 71 lymph nodes examined , 19 were metastatic but due to an adenocarcinoma compatible with the prostate cancer .
the involved lymph nodes were all on the left side , while a focal lymphangiosis from an adenocarcinoma was found in the soft tissue of the right side specimen .
the laryngeal tumor was then classified as pt4a pn0 ( 0/71 ) cmx r0 . due to the nature of lymph node metastases ( adenocarcinoma ) with laryngeal r0 resection in the setting of a patient who presented postoperative complications ( respiratory insufficiency , non - st - segment elevation myocardial infarction [ nstemi ] , and peritracheostoma necrosis ) ,
it was decided not to add immediate adjuvant radiotherapy , but to initiate hormonotherapy with bicalutamide and zoledronic acid .
the ct scan revealed an enlarged lymph node of 4  5 cm , with central necrosis .
the ultrasound - guided fine needle aspiration showed malignant cells of a squamous cell carcinoma .
a surgical approach was rejected because of the poor general condition of the patient , and radiochemotherapy ( cetuximab ) was proposed .
the left cervical metastatic lymph node was treated with 70 gy and the ipsilateral cervical region ( levels ii 
after an initial partial remission , the tumor progressed and the patient developed distant pulmonary metastases .
a further line of chemotherapy ( cisplatin , 5-fu , and cetuximab ) was administrated and the patient died 1 year after the completion of the combined chemoradiotherapy from regional and distant cancer progression .
superficial lymph node metastases are a rare occurrence in prostate cancer , particularly metastases to the supraclavicular lymph nodes which are seen in about 0.33% of patients with prostate carcinoma , and accounts for about 13.4% of all atypical metastatic sites .
supradiaphragmatic spread of prostate cancer has been postulated to occur hematogeneously via the vertebral venous system , or batson plexus , accessible via direct extension from the primary cancer site . in the present case ,
the presence of cervical lymph node prostate adenocarcinoma metastasis concomitantly with a laryngeal squamous cell carcinoma is at least intriguing .
whether the development of the laryngeal cancer influenced the dissemination of the prostatic cancer cell in the cervical lymph nodes remains questionable .
it is more likely that the cervical lymph node metastases were present before the laryngeal cancer and their diagnostic was purely incidental .
also the lymph node recurrence after surgery was different from the initial diagnostic since it was the squamous cell carcinoma that recurred and not the prostatic cancer .
whether the addition of postoperative radiotherapy would have prevented such a recurrence remains uncertain in the light of the rapid progression observed .
however , one can emphasize that the presence of an adenocarcinoma in the lymph nodes changed the prostatic cancer prognostic in this patient , hence contributing to the changing of our usual radiotherapy indication .
the whole setting was surprising , and may remind us of a rare event called  collision tumors  .
collision tumors have been defined differently by various authors with some minor variations . in the present case
one of the oldest definitions of a collision tumor by meyer   is defined as  the meeting and eventual intermingling of two malignant neoplasms arising at independent topographical sites  .
more recently , dodge   added that in order to accept a tumor of mixed structure as a collision tumor , the 2 histologies should be clearly separated in the metastases , and furthermore it requires the absence of any transitional pattern between the 2 tumor types .
finally , spagnolo and heenan   are less restrictive , and allow some transitional pattern , with a zone of intermediate histological appearance .
even if a collision of lymph node metastases of 2 carcinomas from separate sites is very rare , in this case we had the metastatization of 1 carcinoma to the site of the drainage of another carcinoma , but we never found the 2 histological types as close as requested to reach the definition of a collision tumor .
while the occurrence of such a clinical behavior remains rare , the chronology and the sublocation of the recurrences in the present case emphasizes the need of histological verification of different sites of recurrence when 2 or more primary cancers are known in a patient , particularly when the treatments of those primary cancers vary widely .
the authors report no conflicts of interest . the authors alone are responsible for the content and writing of the paper .
brain and head and neck metastases are rare in prostatic carcinoma patients . in this report 
 we present a very uncommon case of the concomitant occurrence of a prostatic adenocarcinoma with neck metastases and an advanced laryngeal squamous cell carcinoma without neck metastases . 
 the presence of cervical lymph node prostate adenocarcinoma metastasis concomitantly with a laryngeal squamous cell carcinoma is at least intriguing and may remind us of a rare event called  collision tumors  . in this case 
 we had the metastatization of 1 carcinoma to the site of the drainage of another carcinoma , but we never found the 2 histological types as close as requested to reach the definition of a collision tumor . 
 this emphasizes the need of histological verification of different sites of recurrence when 2 or more primary cancers are known in a patient , particularly when the treatments of those primary cancers vary widely .