The exact number of the supraclavicular lymph nodes, including the Virchow node, and their distance from anatomical boundaries surrounding it can vary to an extent.

In a study done to provide a detailed description of the surgical anatomy of the supraclavicular lymph node flap for free vascularized lymph node transfer, a surgical method to treat lymphedema, dissections on fresh cadavers showed variation in the number of lymph nodes between the right (average of 1.5 +/- 1.85) and left supraclavicular lymph nodes (average of 3 +/- 2.26). In four out of nine cases, no right supraclavicular lymph nodes were present on the right side while in one out of nine cases, no left supraclavicular lymph nodes were present. Researchers also noted a variation in their mean distance from the jugular notch in the right (8.29 +/- 2.15) and left sides (6.10 +/- 1.21).[10]

Studies have also noted variations in the location of the Virchow node and its histological anatomy relative to the thoracic duct. A study done on five cadavers found that the Virchow node was attached to the dorsal aspect of the carotid sheath (two out of five cadavers) or on the scalenus anterior muscle (three out of five). The study noted different numbers of collaterals coming from the thoracic duct and their communication pattern with the Virchow node. It is also noteworthy that the Virchow node is not always present at the terminal of the thoracic duct (only present in 27% of Japanese subjects).[3]

Investigations of supraclavicular lymph nodes masses include imaging techniques such as computed tomography (CT) or positron emission tomography (PET) followed by ultrasound-guided fine needle aspiration cytology (FNAC).[11][12] Although rapid, painless, inexpensive, safe and does not require anesthetic or hospital admission, FNAC comes with its disadvantages, which include the inability to provide the cellular architecture required for accurate subtyping of lymphomas. Thus, invasive procedures that provide a greater volume of tissue such as an open biopsy of the supraclavicular lymph nodes are an option when the FNAC is nondiagnostic. Despite excisional biopsy being the gold standard in lymphoma cases, a core needle biopsy should be performed alternatively, as it provides adequate results and is less invasive.[13] According to the latest guidelines set by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS), an open biopsy is only necessary if FNAC, core needle biopsy, physical examinations, and other ancillary test prove to be undiagnostic.[14]

As with any surgical procedure, procedures involving the supraclavicular lymph node require a firm grasp of the critical structures and anatomy that surround it. Complications that could arise from procedures such as supraclavicular lymph node harvest or biopsies include but are not limited to[15][14]:

• Carotid and subclavian artery bleeding
• Chylous fistulas, the leaking of lymph from lymphatic vessels, caused by damage to lymphatics such as the thoracic duct
  • Chylous fistulas are preventable by asking the patient to cough; this will compress the intrathoracic lymphatics leading to distension of lymphatic vessels outside the thorax, resulting in a jet of chyle leaking from places of the defect, allowing their localization and ligation before closing the wound.
• Damage to the phrenic nerve, which could lead to dyspnea as the phrenic nerve supplies the diaphragm
• Wound infection
• Tumor seeding in cases of human papillomavirus-positive head and neck squamous cell carcinoma (HPV-positive HNSCC)

Generally speaking, most neck masses in children are of infectious etiology. In adults, however, neck masses in patients who are greater than or equal to 18 years old should always be considered to be malignant until proven otherwise. Thus, the clinical approach to neck masses for adults vs. children vary greatly. It is crucial to keep in mind that cancers of the head and neck, such as squamous cell carcinoma (HNSCC), lymphoma, thyroid, or salivary gland, can present initially as asymptomatic masses.[16][14] Because of this, young adults presenting with an asymptomatic neck mass and an insignificant history may have their diagnosis for underlying malignancies such as mucosal HPV-positive HNSCC delayed.

The differential diagnosis for lymphadenopathy is extensive. It generally categorizes as neoplastic, infectious, inflammatory, reactive, and nondiagnostic. Researchers performed a retrospective 5-year study in a large hospital on 309 supraclavicular masses diagnosed with fine needle aspiration. Results showed that the majority of masses (55%) were malignant, with secondary (metastatic spread) being far more frequent than primary lymphomas (47% vs. 8%, respectively). The most common metastatic malignancies were of lung, breast, uterine, and esophageal origin.[17]

Enlargement of VN, a significant clinical finding termed Troisier sign, can indicate advanced stage 4 gastrointestinal metastasis, which is associated with a 5-year survival of 4%.[6] Other etiologies include, but are not limited to, lymphoma, breast, esophageal, pelvic and testicular cancers.[18] Because of its anatomical relations to critical structures such as the phrenic nerve, the subclavian vessels, and the brachial plexus, enlargement of this node can compress these structures and cause various pathologies such as unilateral phrenic neuropathy, which might lead to dyspnea, vascular and neurogenic thoracic outlet syndromes, and Horner syndrome. Horner syndrome is due to the compression of the lower part of the brachial plexus (C8-T1), leading to the disruption of sympathetic innervation of the eye and usually manifests as four key clinical signs on the ipsilateral side: miosis (constricted pupil), ptosis (droopy eyelid), anhydrosis (decreased sweating) and enophthalmos (sunken eyes). Thus, the presence of a Troisier sign should be kept in consideration when any of these pathologies are present.[19][20]