Discussion
Lung cancer is among the most frequently diagnosed cancers and the world’s leading cause of cancer-related death [3]. The peak-incidence age for lung cancer is between 55 and 65 years, and smoking is a well-established risk factor: active and passive smokers have a 13-fold and 1.5-fold higher risk than nonsmokers, respectively [4]. Lung cancers are classified into Small Cell Lung Cancer (SCLC) and Non Small Cell Lung Cancer (NSCLC). NSCLCs are further divided into three major subtypes: squamous cell carcinoma, adenocarcinoma, and large cell carcinoma [3-5]. Squamous cell carcinoma and SCLC quite often present as a central mass [6].
Lung adenocarcinomas typically arise from the bronchial epithelium or bronchial glandular epithelium, and they are the most common type among nonsmokers and women [3, 5]. Pathologically, adenocarcinoma may display an acinar, papillary, micropapillary, lepidic, or solid growth pattern, with either mucin or pneumocyte marker expression, and it is usually located peripherally with pleural involvement [6]. The most frequent radiological patterns are ground-glass, part-solid, and solid nodules on chest CT scans [7]. Primary lung cancer rarely presents as multiple nodules [8–9].
Multiple nodules in the lung are seen in a wide variety of conditions. The nodular pattern and excavated nodules could be associated to vasculitis such as Wegener and shurg strauss it could also be miliary TB, histoplasmosis, sarcoidosis, pneumoconiosis, bronchoalveolar carcinoma, or pulmonary siderosis, secondary metastasis to the lungs from primary cancers of the thyroid, kidney, and trophoblasts as well as some sarcomas [2, 3] High-resolution CT can help to narrow down the differential diagnoses by distributing the micronodules into centrilobular, perilymphatic, and random patterns. Infectious bronchiolitis commonly presents a centrilobular pattern and sarcoidosis a perilymphatic pattern, whereas a random pattern is suggestive of hematogenous metastases. [10]. A thorough review of the literature revealed a few similar cases reported as multiple nodules primary lung carcinoma [2]. The largest case series is reported from Japan, in which 5 such patients were included [3]. That report concluded that the prevalence of the multiple nodules phenotype is <1% among japanese patients and had poor prognosis.
Khan et al.(11)also showed a 35 year old man with same clincal presentation and mutiple nodules diasgnosed as lepidic adenocarcinoma after lung biopsy.
Wigger et al reported the case of a 66 year-old female patient actively smoking (50 pack-year) with a history of respiratory bronchiolitis-ILD chest CT findings included bilateral, apical ground glass opacities ,numerous enlarging sub-centimeter upper lobe nodules and cysts adenocarcinoma was found in the lung biopsy in the follow up of the patient.(15)
On the other hand Farooqi et al (12) identified 26 (3.7%) lesions that were abutting lung cysts and were later on identified as lepidic adenocarcinomas .
In a more recent retrospective study, Fintelmann et al (13) identified and assessed 30 lung cancers from a total of 2954 primary lung cancers diagnosed at their institution. In these 30 cases, cysts were in or adjacent to lung adenocarcinomas at some point leading up to the histologic diagnosis.
In many screening studies, the findings in cohorts of patients with missed cancers associated with cystic airspaces are highlighted. However, there is a lack of data regarding the percentages of these lesions that are ultimately diagnosed as malignant, and this paucity should prompt pro- spective research trials. Guo et al (14) provided minimal insight, with 4.7% of resected cystic lesions reflecting cancer in their study. However, this percentage cannot be extrapolated to lesions identified at imaging. In addition, these data are limited to patients who were physiologically capable of undergoing surgical resection and reflect an unusually large rate of benign cyst resections.