Prevalence and Malignant Involvement of Calcified Intrathoracic Lymph Nodes in Patients Undergoing Endosonography
Prevalence and Malignant Involvement of Calcified Intrathoracic Lymph Nodes in Patients Undergoing Endosonography
The presence of calcifications, which is a relatively common feature in intrathoracic lymph
 nodes, typically contributes to confer them a heterogeneous aspect during endosonographic
 B-mode examination, but their prevalence and a possible association between calcifications
 and metastatic involvement has never been systematically evaluated. We hypothesize that in
 patients undergoing mediastinal diagnosis or staging of suspected/known lung cancer the
 prevalence of lymph node metastases is similar in calcified and non-calcified lymph nodes.
The presence of calcifications, which is a relatively common feature in intrathoracic lymph
 nodes, typically contributes to confer them a heterogeneous aspect during endosonographic
 B-mode examination, but a possible association between calcifications and metastatic
 involvement has never been systematically evaluated. The most likely reason why this possible
 association has been overlooked up to now is that the presence of calcifications in
 intrathoracic lymph nodes has long been thought to be the consequence of the prior
 involvement from granulomatous diseases (i.e., tuberculosis or sarcoidosis), and as such has
 been considered a sign of benignity. However, the presence of lymph node calcifications at
 ultrasound examination is a known predictor of lymph node metastasis in patients with some
 specific tumours, such as the papillary thyroid carcinoma or the squamous cell carcinoma of
 head or neck. Furthermore, recent radiological-pathological studies have shown that
 metastatic foci from lung cancer are observed in up to 19% calcified mediastinal lymph nodes
 identified at CT in surgical candidates. Finally, a recently published EBUS study has
 reported, for the first time, a very strong association between a very specific pattern of
 mediastinal lymph node calcification, known as "starry sky sign", and metastasis from
 pulmonary, colonic and breast adenocarcinoma. Interestingly, the starry sky sign is
 characterized by the presence of few to countless dot-like calcifications which are too small
 to be seen at CT and can be identified only during EBUS B-mode examination.

 To the best of our knowledge, no studies have been carried out to assess the correlation
 between the presence and the ultrasound pattern of lymph node calcifications and lymph node
 metastasis from lung cancer.
Inclusion Criteria:

 -  Age >18 years at the time of the procedure

 -  Known or suspected lung cancer based on imaging (CT and/or PET/CT)

 -  Endosonography (EBUS and/or EUS) indicated for intrathoracic lymph node
 assessment/sampling according to national and international guidelines: 1) enlarged (>
 1 cm on its short axis at CT) and/or PET positive lymph node; and/or 2) conditions at
 risk for occult mediastinal metastases, such as: i) central primary tumor; ii) primary
 tumor > 3 cm; iii) PET negative primary tumor; iv) ipsilateral hilar metastasis (cN1
 status).

 Exclusion Criteria:

 -  Inability or unwillingness to consent

 -  Compromised upper airway (i.e., concomitant head and neck cancer with upper airway
 obstruction; critical central airway obstruction from any cause)

 -  Contraindication for temporary interruption of the use of antiplatelet (excluded
 aspirin) or anticoagulant drugs

 -  ASA 4