Cancer Adenocarcinoma with Lepidic Growth

Definition

Adenocarcinoma with Lepidic Growth (aka BAC and Bronchiocarcinoma)

is a subtype of adenocarcinoma, accounts for about 5% of lung carcinomas but up to 20% are histologically mixed adenocarcinoma and BAC.

It has an indolent course and in its pure form, is really a carcinoma in situ, showing no invasive changes.  It does have the potential to evolve into frankly malignant and invasive disease

Smoking appears to some extent be a causative link though it has a disproportionate high incidence among non smokers, women and occurs in a slightly younger population.  About 30% of patients with BAC have never smoked.  It also has a higher incidence in Japan.

BAC is sometimes associated with patients suffering from interstitial lung disease (eg scleroderma), and also with the uncommon entity of exogenous lipoid pneumonia. .

Structurally, it is characterized by its unique relatively slow lepidic growth, meaning it grows by scaling along the structure of the alveolus or acinus, but does not  destroy the architecture.  In addition in its pure form it does not invade vascular, lymphatic, or pleural elements.

When it shows invasive properties then it is defined as a mixed BAC adenocarcinoma. Raz  There appears to be an evolving spectrum from benign to malignant, starting with premalignant atypical adenomatous hyperplasia, then BAC, and then  into a subtype of adenocarcinoma. (Travis)

There is a mucinous form (80%) originating in the mucus secreting columnar cells, and tending to a multicentric pattern.  The non mucinous form (20%) arises from the type II pneumocytes of the alveolus, is localized and has a better prognosis.

BAC appears to have characteristic heightened sensitivity to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs).

Clinically, patients in most instances are asymptomatic and many patients are identified by CT screening programs.  When the disease is diffuse, bronchorrhea may occur.

The diagnosis is initially suspected radiologically presenting as a solitary  ground glass opacity (GG0) (45%), as multicentric nodules (GGOs) (25%), or as a consolidation (30%).   Inflammatory or infectious disease is considered in the differential diagnosis, but if the radiologic finding fail to respond to conservative therapy, BAC and its variants become more likely, and surgical biopsy is necessary.

When GGO’s are less than 2cms, they are usually pure BAC.    As solid components within the GGO become more apparent, adenocarcinoma becomes more likely.  When the disease is multifocal,  it defines itself as  IIIb or IV

PET scanning has limited sensitivity so that only about 50% of lesions have a diagnostic SUV >2.5

The final diagnosis is made at pathology, and requires histological examination to determine invasion.  Cytological aspiration is insufficient.

 

Treatment depends on staging. When in pure form – as an in situ disease by definition, treatment is surgical and curative.  Surgery usually consists of lobar resection, and ipsilateral mediastinal lymphadenectomy.  When in the mixed form 10-25% have lymph node involvement and 5% have distant metastases and therefore require additional radiation and chemotherapy.

Adenocarcinoma with Lepidic Growth
Histopathology
Histological sections of a group of  alveoli filled with nests of malignant cells originating from and spreading along the alveolar epithelium without destroying the alveolar walls.(dark pink overlay) The cells seem to be almost hanging from the alveolar epithelium like washing from a washing line. Note groups of tall, columnar, mucin producing cells spreading along preexisting alveolar walls, which is typical of bronchioalveolar carcinoma.
Courtesy Dr Armando Fraire MD 
TheCommonVein.net
32828c08.8s
ADENOCARCINOMA WITH LEPIDIC GROWTH
43 year old male with pneumonic consolidation of malignant origin
Ashley Davidoff MD
TheCommonVein.com
31791c
Single Focus of Ground Glass Opacity without Solid Elements
GGO in the secondary lobule reflects alveolar process and is one of the presenting appearances of unifocal or multifocal BAC.  It is a slow growing in situ disease that may not change in size over two years but continued surveillance is necessary.
Courtesy Ashley Davidoff MD
TheCommonVein.net
45465b01
CT scan I of an 56 year old female with mixed density nodules(ground glass with solid components) shown at pathology to represent adenocarcinoma wit lepidic growth
Ashley Davidoff
TheCommonVein.net
134372
Multicentric GGO’s of Adenocarcinomas with Lepidic Growth
The CT is from a 51 year old male who is a smoker who shows three areas areas of ground glass opacity in the right lower lobe, two that measure close to 2cms each and a third more anterior that measures about 8mms. This case represents multicentric adenocarcinoma with lepidic growth 
Courtesy Ashley Davidoff MD
TheCommonVein.net
 87755.8s
PET Positive Adenocarcinoma in a Background of Multicentric  Adenocarcinoma with Lepidic Growth
The CT is from a 51 year old male who is a smoker who shows a ground glass opacity (GGO) mixed with a solid mass (arrow in a) and multicentric BAC in a lower cut (b) characterised by three areas in the right lower lobe of  partial alveolar opacification.  Ground glass appearance is the result of partial opacification of the alveoli. Two of the GGOs measure close to 2cms each and the third more anterior measures about 8mms. In this instance a PET scan was positive in the area (green ring in d) It is likely that the solid component in image a represents the transformation of BAC – (really a carcinoma in situ) into adenocarcinoma.
Courtesy Ashley Davidoff MD
TheCommonVein.net
87769c02b.8s

 

CT scan of a 65 year old male with multicentric lesions characteristic of adenocarcinoma with lepidic growth. There is a consolidative lesion with air bronchograms in the right upper lobe and multiple other smaller lesions, some of which are ground glass, some solid and some mixed.
Ashley Davidoff
TheCommonVein.net
87770c

Pre and Post Op Studies – 79 year old Male with Adenocarcinoma with Lepidic Growth

CT scan of a 79 year old male with multicentric lesions characteristic of adenocarcinoma with lepidic growth. The dominant lesion is a consolidation in the right lower lobe There are multiple other smaller lesions.
Ashley Davidoff
TheCommonVein.net
79M adenoca with lepidic growth 001
The preop (left) and post op (right) PET scan of a 79 year old male with adenocarcinoma with lepidic growth is shown. The studies on the left side show a preoperative hyperintense lesion at the right base. Post op, no residual hypermetabolic activity is noted.
Ashley Davidoff
TheCommonVein.net
79M adenoca with lepidic growth 002
CT scan I of an 51 year old female with multicentric nodules shown at pathology to represent adenocarcinoma wit lepidic growth
Ashley Davidoff
TheCommonVein.net
134362

Adenocarcinoma with Lepidic Growth

63 year old male witdiffuse bilateral infiltrates reflecting an unusual form of adenocarcinoma
Ashley Davidoff MD
TheCommonVein.net
134332
63 year old male with diffuse bilateral infiltrates reflecting an unusual form of adenocarcinoma
Ashley Davidoff MD
TheCommonVein.net
134334
63 year old male with diffuse bilateral infiltrates reflecting an unusual form of adenocarcinoma
Ashley Davidoff MD
TheCommonVein.net
134336
63 year old male with diffuse bilateral infiltrates reflecting an unusual form of adenocarcinoma
This set of 4 images shows extensive mediastinal and hilar adenopathy and a nodular right adrenal gland most likely reflecting a metastasis (bottom right image)
Ashley Davidoff MD
TheCommonVein.net
134326c
Diffuse mucinous bronchioloalveolar carcinoma in a 78-year-old man. (a) High-resolution CT scan
shows a bilateral crazy-paving pattern and centrilobular nodules. (b) Photomicrograph (original magnification,
400; hematoxylin-eosin stain) of a specimen from open lung biopsy shows replacement of the alveolar epithelium
by epithelial neoplastic cells with abundant intracytoplasmic mucin (arrows).
Rossi, S.E et al “Crazy-Paving” Pattern at Thin-Section CT of  the Lungs: RadiologicPathologic Overview Radiographics  Volume 23 – Number 6,  2003

 

Links and References