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Background: Pulmonary and mediastinal paragangliomas are rare tumors that may have neuroendocrine activity or be non-functional, incidental, in asymptomatic patients, or causing mass effect symptoms. Although being low-grade tumors, they can display an aggressive behaviour, developing local infiltration and distant metastases. We report our experience with three endothoracic paragangliomas and a Literature review, to point out diagnostic difficulties and problems related to surgical treatment. Methods: From 2009 to 2017, we treated 3 patients with histological diagnosis of paraganglioma: 2 pulmonary, 1 mediastinal. No one presented catecholamine-secreting syndromes; pulmonary cases were asymptomatic, while the mediastinal one had aspecific cough and dyspnea. Imaging diagnosis was based on chest computerized tomography (CT) and magnetic resonance imaging (MRI) scan. No patient had preoperative histological diagnosis. Intraoperative pathological examination was suggestive for malignancy: in pulmonary cases, wedge resection and lobectomy were performed; the middle mediastinal mass was completely removed after challenging dissection, isolation and section of numerous vascular pedicles. Results: Postoperative course was uneventful in all cases. No patient received adjuvant treatments. At a median follow-up of 47 months (range, 6-102 months), two patients are alive, without local or distant recurrence; one patient died 6 months after surgery, due to disease progression. Conclusions: Endothoracic paragangliomas, rare and often asymptomatic tumors, are of difficult diagnosis and should be considered malignant tumors, due to the potential aggressive behaviour of cases with high mitotic index and the frequent possibility of recurrence and metastases. Surgical resection is the treatment of choice and careful intraoperative manipulation is recommended, due to the high vascularity of these tumors, to prevent complications. After complete excision, long-term prognosis is generally good. However, even after surgical removal, a close, periodical and lifelong follow-up is mandatory.

Pulmonary segmentectomy is a common surgical procedure in thoracic surgery nowadays.Though this technique helps preventing postoperative pulmonary function loss, potential challenges are the management of air leaks and the difficulty of palpating ground-glass components during surgery, as well as how to deal with the intersegmental planes. Several techniques have been proposed for the identification and treatment of the intersegmental planes during sublobar anatomical resections: this review focuses on preoperative planning and workup and intraoperative strategies. Three-dimensional computed tomography bronchography and angiography (3D-CTBA), virtual-assisted mapping (VAL-MAP) using bronchoscopy multi-spot dye marking and three-dimensional computed tomography (3D-CT) are preoperative tools that may facilitate the planning of operation. Inflation-deflation techniques, infrared-fluorescence-enhanced method combined with bronchial and intravenous injection of indocyanine green (ICG) and near-infrared fluorescence (NIF) mapping with ICG have been described as intraoperative strategies to identify the intersegmental plane. The treatment and section of the intersegmental planes is mainly accomplished by stapler and electrocautery or energy devices. The use of staplers reduces postoperative air leaks, bleeding risks and operative time but seems to reduce preserved lung volume, compromising adjacent lung expansion; in addition, higher costs and sometimes non-adequate oncological margins, being a non-anatomical technique have been described. The electrocautery and energy devices allow for a more anatomical and precise dissection maintaining safe oncological margins, with a better lung expansion and so an increased postoperative lung function. Time consuming procedure and frequent requirement of aero-haemostatic tools to treat air and blood leaks are the main drawbacks. In conclusion, there are several methods to identify and treat the intersegmental planes but there are no significant differences between the different tools, therefore the use of one technique rather than another depends overall on surgeon's preference and the location of the segment.

<b><i>Background:</i></b> Several studies suggested the association between tobacco and cannabis smoking and the risk of primary spontaneous pneumothorax (PSP), but none demonstrated cannabinoids in human lung tissues. <b><i>Objectives:</i></b> The aim of this study was to identify cannabinoids in lung specimens of young cannabis smokers, operated for PSP, and investigate on their pathologic findings, to determine the role of cannabis in PSP pathogenesis. <b><i>Method:</i></b> A prospective, multicenter study was conducted, enrolling patients admitted for PSP. Inclusion criteria were PSP requiring surgical treatment and history of cannabis smoking, associated or not to tobacco. Control cases were nonsmokers, and tobacco only smokers operated for PSP. Lung apex wedge resection by video-assisted thoracic surgery was performed. Two lung specimens, for pathological and toxicological examination, were taken from each patient. <b><i>Results:</i></b> Twenty-nine male patients were enrolled: 21 (72.4%) tobacco and cannabis smokers, 2 (7%) cannabis only smokers, 3 (10.3%) tobacco only smokers, 3 (10.3%) nonsmokers; all underwent lung apicectomy, 4 bilateral surgery, for a total of 33 procedures. Typical PSP pathologic findings were mainly detected in control cases, other alterations in cannabis users. Lung specimens resulted positive for cannabinoids on 22/33 cases (19/22 reported being, 3/22 not being cannabis smokers), negative on 11/33 (3/11 reported not being, 7/11 having been cannabis smokers, 1/11 cannabis smoker). <b><i>Conclusions:</i></b> Our study demonstrated the presence of cannabinoids and particular pathologic alterations in lung tissues of young cannabis smokers with PSP, supporting the correlation between this disease and marijuana abuse and suggesting spontaneous pneumothorax “secondary to marijuana” as a new nosological entity.

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