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.