The four most common causes of mediastinal lymphadenopathy are sarcoidosis, lymphoma, and metastatic carcinoma, and granulomatous infections.
Lymph node locations have been traditionally divided into 14 stations according to surgical landmarks from mediastinoscopy and thoracotomy

Nodal Zone Lymph node station
Upper zone Low cervical, supraclavicular, sternal notch (1R – 1L)
Upper paratracheal (2R – 2L)
Prevascular (3A) and retrotracheal (3P)
Lower paratracheal (4R – 4L)
Aortopulmonary zone Subaortic (aortopulmonary window - 5)
Para-aortic (ascending aorta or phrenic nerve - 6)
Subcarinal zone Subcarinal (7)
Lower zone Paraesophageal (8)
Pulmonary ligament (9)
Hilar zone Hilar (10)
Interlobar superior (11 S) and inferior (11 I)
Peripheral zone Lobar (12)
Segmental (13)
Subsegmental (14)

Selection of the biopsy procedure depends on the lymph node station and full patient history of prior neck and thoracic surgery. The procedure options include cervical mediastinoscopy, thoracoscopy, anterior mediastinotomy, endobronchial ultrasound, navigational bronchoscopy, and esophageal ultrasound.

Aim of the work
The aim of this study was to compare between the efficacy, accessibility and safety of uniport VATS and cervical mediastinoscopy in mediastinal lymph node biopsy for both station 2R and 4R.