Prostate cancer (CaP) is a leading oncological diagnosis amongst men, with the bone, regional lymph nodes, liver and thorax being common metastatic sites for CaP1. Though metastatic CaP is commonly talked about in association with bone metastasis, the possibility of atypical metastasis should not be overlooked2, and provide an interesting diagnostic challenge to the treating urologist. This includes the development of cervical lymphadenopathy; which remains a rather rare initial presentation and is seen in <0.1% of the patients diagnosed with prostatic carcinoma3.
Our tertiary-care teaching hospital recently encountered a 55-year-old male who presented to the orthopaedic outpatient department with chief complaints of lower back pain and swelling in the left side of the neck for the past 2 months. Physical examination revealed multiple enlarged cervical lymph nodes, 2 cm in size, non-tender, hard and fixed to the overlying skin. Aspiration cytology of left lower cervical lymph nodes revealed poorly differentiated adenocarcinoma. In search of a possible primary for cervical metastasis, a CT (Computed Tomography) scan of the thorax and abdomen was done. The scan reported moderate prostatomegaly, perirectal and retroperitoneal lymphadenopathy, lymph nodal mass along the left external iliac vessels encasing the left distal ureter with upstream moderate hydroureteronephrosis, mediastinal lymphadenopathy and sclerotic lesions involving the dorsolumbar vertebrae and the pelvic bones suggestive of metastasis. On further evaluation, the PSA (Prostate-Specific Antigen) level was found to be 364.8 ng/ml.
The patient was then planned for an MRI (magnetic resonance imaging) of the prostate gland to evaluate for suspected prostatic carcinoma. The MR scan showed 2.8 x 3.8 x 4 cm of prostate and an ill-marginated T2 hypointense mass involving the peripheral gland on the left side in the region of the prostatic apex with extraprostatic extension(PIRADS V). TRUS-guided prostate biopsy was planned and revealed poorly differentiated adenocarcinoma of the prostate. The patient is now being scheduled for hormone ablation therapy as per Institute protocol, in view of metastatic prostate cancer.
Prostate cancer should always be considered in the differential diagnosis of elderly men presenting with supraclavicular lymphadenopathy in the setting of an unknown primary malignancy; even in the absence of any lower urinary tract symptoms. As stated above, cervical lymph node involvement as an isolated presenting complaint is seen in <0.1% of individuals with prostatic cancer3. Since cancers presenting with cervical lymphadenopathy are usually acquired from malignancies involving the aerodigestive tract2,4, many of these patients first visit the Medicine or Otorhinolaryngology departments; eventually prolonging their evaluation before appropriate oncological therapy is initiated.
There have been two theories for why CaP may spread to the supraclavicular nodes. Batson et al suggested that head and neck metastases from CaP occur due to hematogenous spread through the vertebral venous system (Batson's plexus)5. However, hematogenous dissemination fails to delineate the propensity of CaP to metastasize to the left cervical region, while right-side involvement remains fairly unusual5. The more plausible theory hence, is of a lymphatic spread to cervical lymph nodes. Prostate is richly supplied by lymphatics which drain into the obturator, hypogastric and presacral nodes; and from these to the iliac and paraaortic nodes, before subsequently draining into the thoracic duct6. The lymphatic drainage from the prostate then enters the systemic blood circulation via the left subclavian vein, that allows tumour cells to lodge into left cervical nodes, owing to the proximity of these nodes to the point-of-entry of the thoracic duct into the left subclavian vein7.
Cervical lymph node involvement in prostate cancer is almost uniformly associated with a widespread metastatic disease and is thus, a poor prognostic factor in patients with prostate cancer. For such patients, the survival rates are significantly reduced. Interestingly, owing to the underlying widespread metastatic disease, cervical lymphadenopathy has a rather strong association with PSA levels beyond 100 ng/ml; with 26 / 29 patients (89.6%) satisfying this biochemical finding 8. Even in the current case, our patient had a PSA level of 364.8 ng/ml at the time of presentation. Such an association suggests at least one low-cost solution to the diagnostic challenge posed by this unusual clinical presentation for CaP; i.e. – an opportunistic PSA testing in all elderly males presenting with supraclavicular lymphadenopathy of unknown etiology. Of course; in a surgical/urological clinic, this PSA assay should be coupled with DRE (digital rectal examination) as a part of the initial physical evaluation of such patients.