Cervical lymphadenopathies are a common site of metastasis for malignant neoplasms and in some cases the first sign of malignancy. Head and neck primary tumors are the most common etiology, arising from a distant primary site in about 1-50%, depending on the series, including breast and lung tumours, melanoma, lymphoma and abdominal neoplasms, among others [3,5].

Virchow's node refers to left supraclavicular lymphadenopathy secondary to abdominal malignancy. The term was coined by the German pathologist Rudolf Karl Virchow, who described this association in 1848 in his publication Zur Diagnose der Krebse in Unterleibe. Due to the importance of the physical examination at that time, this finding was of great importance for the diagnosis and management of patients [1,2].

Gastric, hepatocellular and renal cell carcinomas have a particular propensity to involve Virchow's node, as well as bladder, prostate and ovarian cancers, with a global incidence of 1-2% in most cases [3,4].

Anatomical overview/Supraclavicular and Lymphatic System Anatomy

The supraclavicular fossa is a depression in the lower neck between the trachea medially, the sternocleidomastoid, platysma and deep cervical fascia anteriorly, the anterior scalene posterolaterally, the carotid artery and internal jugular vein posteromedially, and the subclavian artery posteroinferiorly [2].

Lymphatic drainage of the head and neck is predictable and may help us to localize a primary head and neck neoplasm, depending on the level at which we find the lymphadenopathy. However, lymphatic drainage of nodules arising from distant neoplasms is more difficult to establish, although they are known to have a predilection for the left supraclavicular space [2,3].

The cisterna chyli is the central point of lymphatic drainage for the abdomen and lower extremities, serving as the central depository for the lower intercostal, gastric, superior and inferior mesenteric, lumbar, internal and external iliac lymphatics. The cisterna chyli subsequently empties into the thoracic duct, which then drains superiorly in the thorax, subsequently draining the left jugular, left subclavian, and left mediastinal nodes. At the terminal end of the thoracic duct is Virchow’s node, the terminal node of the thoracic duct, and the thoracic duct finally empties into the left subclavian vein [2,3].

The supraclavicular region presents a challenge to exploration due to the anatomical complexity resulting from its location and the minimum size of the lymphadenopathies. Consequently, the use of imaging tests is imperative [3,5].

With regard to the computed tomography (CT), it is important to include this region in the thoracoabdominal studies and to make an adequate assessment of it. Normal lymph nodes measure less than 1cm in the short axis but can be difficult to detect in this small area if you are not used to analyse it [4].

Ultrasound, alternatively, is a highly sensitive technique for detecting small size pathological lymphadenopathies. Metastatic nodes tend to be round, hypoechoic, without fatty hilium and have poorly defined borders [4].

PET also has high sensitivity for detecting pathological lymphadenopathy, as well as for detecting primary occult neoplasia.

Ultrasound-guided fine-needle aspiration citology (FNA)

Ultrasound-guided fine-needle aspiration cytology (FNA) is a valuable diagnostic modality for supraclavicular lymphadenopathy of unknown neoplasia due to its high diagnostic accuracy [3].

Important considerations regarding the technique:

    - Low cost.

    - No need for sedation.

    - Diagnostic rates up to 90%.

    - Safe technique for small lesions or when the target is close to sensitive structures.

    - Real-time examination.

    - Low risk of bleeding or other complications.

    - Outpatient procedure.

Because of all the characteristics described above, this test is particularly indicated for older patients or those with significant co-morbidities to avoid more invasive tests.

Analysis of cytological tests

Inmunohistochemistry and molecular studies have been a major advance since their first use, allowing precise diagnosis of tumours through the evaluation of molecular markers that may be unique to the primary tumour site [3].

Maine molecular markers:

• GATA 3: Bladder cancer
• PAX8: Renal Cell cancer
• CDX2: Gastric cancer
• PSA,P50LS, NKX3: Prostate cancer