Lung
Adenocarcinoma
Minimally invasive
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Last author update: 22 February 2021
Last staff update: 19 April 2023
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PubMed Search: Adenocarcinoma minimally invasive [TI] lung
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1Cite this page: Keow J, Cecchini MJ. Minimally invasive. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumoradenominimallyinvasive.html. Accessed April 23rd, 2024.
Definition / general
- Primary lung adenocarcinoma measuring ≤ 3 cm in greatest dimension, with ≤ 0.5 cm area of either stromal invasion or nonlepidic growth pattern (Arch Pathol Lab Med 2013;137:685, J Thorac Oncol 2011;6:244)
Essential features
- Tumor with noninvasive (lepidic) and invasive components
- Total tumor size must be less than 3 cm
- Invasive or nonlepidic components must be less than 0.5 cm
- Invasive component can be of any subtype other than lepidic
- No lymphovascular invasion, tumor necrosis or pleural invasion is present
- Usually nonmucinous but can rarely occur in mucinous tumors
Terminology
- Minimally invasive adenocarcinoma (MIA)
- Microinvasive adenocarcinoma
- Older terminology used: bronchoalveolar carcinoma; however, this is obsolete and should no longer be utilized
ICD coding
- ICD-O: 8250/2 - minimally invasive adenocarcinoma, nonmucinous (international code)
- ICD-O: 8257/3 - minimally invasive adenocarcinoma, mucinous (international code)
- ICD-10: C34.9 - malignant neoplasm of unspecified part of unspecified bronchus or lung
- ICD-11: XH3QM0 - minimally invasive adenocarcinoma, nonmucinous
- ICD-11: XH2098 - minimally invasive adenocarcinoma, mucinous
Epidemiology
- F > M (Cancer 2014;120:2883)
- More common in Asian populations (Am J Surg Pathol 2014;38:448)
Sites
- Usually located in the peripheral lung parenchyma (Ann Thorac Surg 2000;69:893, Lung Cancer 2000;29:179)
Pathophysiology
- Hypothesized to form after a multistep progression from atypical adenomatous hyperplasia to adenocarcinoma in situ to minimally invasive adenocarcinoma (J Thorac Oncol 2008;3:340)
Etiology
- Tobacco smoking (Cancer Epidemiol Biomarkers Prev 2015;24:1902; Gen Thorac Cardiovasc Surg 2015;63:608)
- However, minimally invasive adenocarcinoma is not as strongly associated with smoking as other subtypes of adenocarcinoma (Int J Mol Sci 2018;19:1259)
Clinical features
- Generally asymptomatic, discovered as incidental mixed solid and ground glass lesions on CT scans (N Engl J Med 2013;368:1980)
Diagnosis
- Slow growing, ground glass opacity (see Radiology description)
- Biopsies will show adenocarcinoma with lepidic growth pattern
- Diagnosis can only be made on the resection specimen and cannot be made with limited tissue sampling (Arch Pathol Lab Med 2013;137:668, Arch Pathol Lab Med 2007;131:1027)
Radiology description
- Early lesions may present as a ground glass opacity rather than a solid nodule (J Thorac Oncol 2011;6:244)
- Foci of invasion are generally solid, surrounded by areas with a ground glass opacity (Hum Pathol 2016;51:41, Ann Oncol 2015;26:156)
Radiology images
Images hosted on other servers:
Ground glass lesion on CT scan
Prognostic factors
- Minimally invasive adenocarcinoma (pT1mi) has a more favorable prognosis than early stage invasive adenocarcinoma (pT1a) and should be distinguished accordingly (J Clin Oncol 2012;30:1438, J Thorac Cardiovasc Surg 2013;146:17)
- Since tumor growth is often indolent, a 100% disease free survival may be achieved if completely resected (Am J Surg Pathol 2014;38:448)
Case reports
- 12 year old girl in posttreatment for a rhabdomyosarcoma developed a minimally invasive adenocarcinoma (Pediatr Blood Cancer 2016;63:344)
- 13 year old boy in posttreatment for osteosarcoma developed a minimally invasive adenocarcinoma (Pediatr Dev Pathol 2013;16:387)
- 64 year old woman with a resected minimally invasive adenocarcinoma and adenocarcinoma in situ (Asian Cardiovasc Thorac Ann 2019;27:45)
Treatment
- Surgical excision with close followup (Am J Surg Pathol 2014;38:448, Clin Lung Cancer 2016;17:e57)
- Adjuvant therapies are generally not indicated (J Thorac Cardiovasc Surg 2017;154:1100, Surg Today 2015;45:1341)
Gross description
- Peripheral, ill defined, firm, white tumor with solid areas; ill defined areas correspond to lepidic growth pattern and solid areas correspond to invasive component (Hum Pathol 2016;51:41)
- Necrosis and frank pleural invasion should be absent
Gross images
Contributed by Sarah Aziz, M.D.
Lobectomy specimen
Microscopic (histologic) description
- Primary lung adenocarcinoma measuring ≤ 3 cm in greatest dimension, with ≤ 0.5 cm area of either stromal invasion or nonlepidic growth pattern (acinar, micropapillary, papillary, solid, colloid, fetal or invasive mucinous patterns)
- Foci of stromal invasion characterized by angulated glands, desmoplastic stroma and increased cytologic atypia (Cancer 1995;75:2844)
- Size of invasion should be measured as the largest focus of invasion (Am J Surg Pathol 2014;38:448, Arch Pathol Lab Med 2013;137:685)
- If there are multiple foci of invasion, the invasive size can be measured as a sum of the percentage of the invasive components in each section multiplied against the greatest tumor dimension (the aggregate invasive size should be ≤ 0.5 cm to render the diagnosis of a minimally invasive adenocarcinoma) (Am J Surg Pathol 2014;38:448, Surg Today 2019;49:828)
- Necrosis, lymphovascular invasion, pleural invasion and spread through air spaces must be absent
Microscopic (histologic) images
Contributed by Jonathan Keow, M.D., Ph.D.
Noninvasive and invasive components
Noninvasive lepidic adenocarcinoma
Focus of invasive adenocarcinoma
Positive stains
- CK7
- TTF1, Napsin A
- References: J Clin Pathol 1997;50:30, Am J Clin Pathol 1994;102:764
Negative stains
Sample pathology report
- Lung, right lower lobe, lobectomy:
- Minimally invasive adenocarcinoma, pT1mi NX MX (see synoptic report)
Differential diagnosis
- Invasive adenocarcinoma, lepidic predominant pattern:
- Invasive foci must total 0.5 cm or more in aggregate
- Adenocarcinoma in situ / atypical adenomatous hyperplasia:
- No invasive component
Additional references
Board review style question #1
Which of the following tumors would be classified as a minimally invasive adenocarcinoma?
- 2 cm lepidic predominant tumor with a 0.8 cm invasive component
- 2 cm lepidic predominant tumor with a 0.4 cm invasive component
- 2 cm lepidic predominant tumor with a 0.4 cm invasive component with pleural and lymphovascular invasion
- 5 cm lepidic predominant tumor with a 0.4 cm invasive component
Board review style answer #1
B. 2 cm lepidic predominant tumor with a 0.4 cm invasive component
Comment Here
Reference: Adenocarcinoma - minimally invasive
Comment Here
Reference: Adenocarcinoma - minimally invasive
