Hear Hooves, Think Zebras: A Case Report & Systematic Literature Review of Isolated Neck Node Metastases from Prostate Cancer

Abstract

Most cancers that metastasize to the cervical lymph nodes are from the upper aerodigestive tract. We use a case report and systematic literature review to highlight a very rare example of atypical metastatic spread to the cervical lymph nodes from advanced prostate cancer without involvement of other lymph node groups. All possible clinical, imaging and pathological documents were collected from the patient’s chart. Those documents were subjected to an independent review and data abstraction. A literature search was performed using relevant key words and MESH headings. Additional papers were found using the ‘cited by’ and ‘related articles’ functions of the search engines, and the references section of relevant papers. In July 2012, a 56 year old man presented with PSA 8ng/ml, cT2a, Gleason 8 prostate adenocarcinoma. Metastatic workup was negative and he had a radical prostatectomy. He had extensive positive surgical margins, pT3b N0, Gleason 9, with post-operative PSA of 0.77 and underwent salvage radiotherapy to the prostate bed with 2 years of adjuvant androgen deprivation therapy (ADT). In July 2015, he developed widespread bony metastases and received 6 cycles of chemotherapy with ADT. He subsequently developed castrate-resistant disease. In December 2017, the patient reported a painful lump in his left neck. PSA was 0.22 ng/ml. Ultrasound-guided aspiration confirmed metastasis from prostate cancer. CT revealed a level 3 neck node, 3cm in diameter. Whole body imaging indicated no other lymph node or visceral metastases. The patient then received 3 of 5 cycles in a phase 1 trial of an oncolytic virus plus monoclonal antibodies, but was removed from the study when his neck node disease progressed. Imaging showed necrotic nodes at left neck levels 2, 3, 5A. There was an infiltrative soft tissue mass surrounding the left C1 transverse process and encasing the left vertebral artery just below the skull base. There was no right-sided neck involvement. In July 2018, IMRT was used to deliver 51Gy in 20 fractions to a geometrically complex CTV in the left neck. To date, the neck nodes have reduced, but have not resolved completely. He still has no other lymph node or visceral metastases, and continues on ADT with a latest PSA of 1. An exhaustive review of the literature resulted in the identification of 13 case reports of cervical lymph node metastases from advanced prostate cancer, spanning 17 years. Misdiagnosis and delays to appropriate treatment were common due to the rarity of the phenomenon. 11 of 13 document nodes only in the left neck, and 5 of 13 report no lymphadenopathy except in the neck. All but one case were successfully palliated using ADT + chemotherapy. The remaining case saw disease progression on ADT, and received 70Gy chemo-rads to the left neck. This case report and literature review indicate that, although exceedingly rare, it is possible for advanced prostate cancer to metastasize to the left cervical lymph nodes without involvement of other lymph node groups. Improper assumptions about the site of primary disease, leading to inappropriate treatment choices, has been reported in the literature. ADT, chemotherapy and state-of-the-art radiotherapy can all be considered for palliation, on a case-by-case basis.