Adenocarcinoma of the lung

Changed by Brian Gilcrease-Garcia, 11 Aug 2018

Updates to Article Attributes

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Adenocarcinoma of the lung is one of the non-small cell carcinomas of the lung and is a malignant tumour with glandular differentiation or mucin production. This tumour exhibits various patterns and degrees of differentiation, including lepidic, acinar, papillary, micropapillary, and solid with mucin formation 1

Epidemiology

It is now considered the most common histological subtype in terms of prevalence.

Clinical presentation

Early symptoms are fatigue with mild dyspnoea followed by a chronic cough and haemoptysis at a later stage.

Classification

Classification of the tumour subtypeLung adenocarcinoma is basedprimarily categorized on the estimatebasis of histopathologic evaluation, although testing for genetic mutations (e.g. EGFR, KRAS) is becoming increasingly important for consideration of therapy 1.

Mucinous adenocarcinoma is recognized as distinct from non-mucinous adenocarinomas, given differences in imaging appearance, genetics, and clinical behavior.

Next, lung adenocarcinomas are divided into 'preinvasive', 'minimally invasive', and 'invasive' disease on the percentagebasis of greatest depth of invasion on on resection specimens (this assessment is not possible on limited biopsies) 1:

For invasive adenocarcinoma, further subcategorization is recommended according to the dominant histologic pattern. Both mucinous and non-mucinous adenocarcinomas typically consist of a mixture of histologic patterns and(all previously known as "mixed subtype", a now defunct category), but reporting of the predominant subtype. The terminology of mixed subtype is to be avoidedspecifically recommended for non-mucinous lesions 1:

Variants of invasive adenocarcinoma:

Radiographic features

Sometimes it is impossible to radiographically distinguish between other histological lung cancer types.

A lung nodule is a rounded or irregular region of increased attenuation measuring less than 3 cm. The amount of attenuation can further classify the nodules as either ground glass, subsolid or solid.1,2 

Histologically, the ground-glass attenuation corresponds to a lepidic growth pattern and the solid component corresponds to invasive patterns. Hence, the preinvasive category of adenocarcinoma in situ, minimally invasive adenocarcinoma, and the invasive subtype of lepidic-predominant adenocarcinoma are often seen as a ground-glass nodule or a subsolid nodule with a predominant ground-glass component. On the other hand, the remaining invasive subtypes of adenocarcinoma usually manifest as a solid nodule but may also be subsolid and are only occasionally seen as ground glass nodule 1,2

The invasive mucinous adenocarcinoma subtype (formerly mucinous BAC) can have a variable appearance, including consolidation, air bronchograms, or multifocal subsolid nodules or masses 2.

Treatment and prognosis

RecommendationThere are society guideline recommendations for the imaging follow-up of both ground glass and solid nodules: Fleischner Society guidelines. Please consult the 2017 Macmahon et al. article, Guidelines for management of incidental pulmonary nodules detected on CT images: from the Fleischner Society 2017 3.

  • -<p><strong>Adenocarcinoma of the lung </strong>is one of the <a href="/articles/non-small-cell-lung-cancer-2">non-small cell carcinomas of the lung</a> and is a malignant tumour with glandular differentiation or mucin production. This tumour exhibits various patterns and degrees of differentiation, including lepidic, acinar, papillary, micropapillary, and solid with mucin formation <sup>1</sup>. </p><h4>Epidemiology</h4><p>It is now considered the most common histological subtype in terms of prevalence.</p><h4>Clinical presentation</h4><p>Early symptoms are fatigue with mild dyspnoea followed by a chronic cough and <a href="/articles/haemoptysis-1">haemoptysis</a> at a later stage.</p><h4>Classification</h4><p>Classification of the tumour subtype is based on the estimate of the percentage of histologic patterns and the predominant subtype. The terminology of mixed subtype is to be avoided:</p><ul>
  • +<p><strong>Adenocarcinoma of the lung </strong>is one of the <a href="/articles/non-small-cell-lung-cancer-2">non-small cell carcinomas of the lung</a> and is a malignant tumour with glandular differentiation or mucin production. This tumour exhibits various patterns and degrees of differentiation, including lepidic, acinar, papillary, micropapillary, and solid with mucin formation <sup>1</sup>. </p><h4>Epidemiology</h4><p>It is now considered the most common histological subtype in terms of prevalence.</p><h4>Clinical presentation</h4><p>Early symptoms are fatigue with mild dyspnoea followed by a chronic cough and <a href="/articles/haemoptysis-1">haemoptysis</a> at a later stage.</p><h4>Classification</h4><p>Lung adenocarcinoma is primarily categorized on the basis of histopathologic evaluation, although testing for genetic mutations (e.g. <em>EGFR</em>, <em>KRAS</em>) is becoming increasingly important for consideration of therapy <sup>1</sup>.</p><p><a href="/articles/invasive-mucinous-adenocarcinoma-of-the-lung-1">Mucinous adenocarcinoma</a> is recognized as distinct from non-mucinous adenocarinomas, given differences in imaging appearance, genetics, and clinical behavior.</p><p>Next, lung adenocarcinomas are divided into 'preinvasive', 'minimally invasive', and 'invasive' disease on the basis of greatest depth of invasion on on resection specimens (this assessment is not possible on limited biopsies) <sup>1</sup>:</p><ul>
  • -<a href="/articles/lepidic-predominant-adenocarcinoma-of-lung">lepidic predominant adenocarcinoma of the lung</a>: formerly non-mucinous <a href="/articles/adenocarcinoma-in-situ-minimally-invasive-adenocarcinoma-and-invasive-adenocarcinoma-of-lung">bronchioloalveolar carcinoma (BAC)</a> pattern, with &gt; 5 mm invasion</li>
  • -<li><a href="/articles/acinar-predominant-adenocarcinoma-of-lung">acinar predominant adenocarcinoma of the lung</a></li>
  • -<li><a href="/articles/papillary-predominant-adenocarcinoma-of-lung">papillary predominant adenocarcinoma of the lung</a></li>
  • +<a href="/articles/preinvasive-adenocarcinoma-lesion-of-the-lung">preinvasive adenocarcinoma lesions</a>: no invasion</li>
  • +<li>
  • +<a href="/articles/minimally-invasive-adenocarcinoma-of-the-lung-1">minimally invasive adenocarcinoma</a>: ≤5 mm invasion</li>
  • +<li>
  • +<a href="/articles/adenocarcinoma-of-the-lung">invasive adenocarcinoma</a>: &gt;5 mm invasion</li>
  • +</ul><p>For invasive adenocarcinoma, further subcategorization is recommended according to the dominant histologic pattern. Both mucinous and non-mucinous adenocarcinomas typically consist of a mixture of histologic patterns (all previously known as "mixed subtype", a now defunct category), but reporting of the predominant subtype is specifically recommended for non-mucinous lesions <sup>1</sup>:</p><ul>
  • +<li>
  • +<a href="/articles/lepidic-predominant-adenocarcinoma-of-the-lung-1">lepidic predominant adenocarcinoma of the lung</a>: formerly non-mucinous <a href="/articles/adenocarcinoma-in-situ-minimally-invasive-adenocarcinoma-and-invasive-adenocarcinoma-of-lung">bronchioloalveolar carcinoma (BAC)</a> pattern, with &gt; 5 mm invasion</li>
  • +<li><a href="/articles/acinar-predominant-adenocarcinoma-of-the-lung-1">acinar predominant adenocarcinoma of the lung</a></li>
  • +<li><a href="/articles/papillary-predominant-adenocarcinoma-of-the-lung">papillary predominant adenocarcinoma of the lung</a></li>
  • -<a href="/articles/invasive-mucinous-adenocarcinoma-of-lung">invasive mucinous adenocarcinoma</a> (formerly mucinous BAC)</li>
  • +<a href="/articles/invasive-mucinous-adenocarcinoma-of-the-lung-1">invasive mucinous adenocarcinoma</a> (formerly mucinous BAC)</li>
  • -</ul><h4>Radiographic features</h4><p>Sometimes it is impossible to radiographically distinguish between other histological lung cancer types.</p><p>A <a href="/articles/pulmonary-nodule-1">lung nodule</a> is a rounded or irregular region of increased attenuation measuring less than 3 cm. The amount of attenuation can further classify the nodules as either <a href="/articles/ground-glass-density-nodule">ground glass</a>, <a href="/articles/part-solid-lung-nodule-1">subsolid</a> or <a href="/articles/solid-lung-nodule">solid</a>.<sup>1,2</sup> </p><p>Histologically, the ground-glass attenuation corresponds to a lepidic growth pattern and the solid component corresponds to invasive patterns. Hence, the preinvasive category of adenocarcinoma in situ, minimally invasive adenocarcinoma, and the invasive subtype of lepidic-predominant adenocarcinoma are often seen as a ground-glass nodule or a subsolid nodule with a predominant ground-glass component. On the other hand, the remaining invasive subtypes of adenocarcinoma usually manifest as a solid nodule but may also be subsolid and are only occasionally seen as ground glass nodule <sup>1,2</sup>. </p><p>The invasive mucinous adenocarcinoma subtype (formerly mucinous BAC) can have a variable appearance, including consolidation, air bronchograms, or multifocal subsolid nodules or masses <sup>2</sup>.</p><h4>Treatment and prognosis</h4><p>Recommendation for follow-up of solid nodules is as per <a href="/articles/fleischner-society-pulmonary-nodule-recommendations-1">Fleischner Society</a><a href="/articles/fleischner-society-pulmonary-nodule-recommendations-1"> guidelines</a>. Please consult the 2017 Macmahon et al. article, Guidelines for management of incidental pulmonary nodules detected on CT images: from the <a title="Fleischner Society" href="/articles/fleischner-society">Fleischner Society</a> 2017 <sup>3</sup>.</p>
  • +</ul><h4>Radiographic features</h4><p>Sometimes it is impossible to radiographically distinguish between other histological lung cancer types.</p><p>A <a href="/articles/pulmonary-nodule-1">lung nodule</a> is a rounded or irregular region of increased attenuation measuring less than 3 cm. The amount of attenuation can further classify the nodules as either <a href="/articles/ground-glass-density-nodule">ground glass</a>, <a href="/articles/part-solid-lung-nodule-1">subsolid</a> or <a href="/articles/solid-lung-nodule">solid</a>.<sup>1,2</sup> </p><p>Histologically, the ground-glass attenuation corresponds to a lepidic growth pattern and the solid component corresponds to invasive patterns. Hence, the preinvasive category of adenocarcinoma in situ, minimally invasive adenocarcinoma, and the invasive subtype of lepidic-predominant adenocarcinoma are often seen as a ground-glass nodule or a subsolid nodule with a predominant ground-glass component. On the other hand, the remaining invasive subtypes of adenocarcinoma usually manifest as a solid nodule but may also be subsolid and are only occasionally seen as ground glass nodule <sup>1,2</sup>. </p><p>The invasive mucinous adenocarcinoma subtype (formerly mucinous BAC) can have a variable appearance, including consolidation, air bronchograms, or multifocal subsolid nodules or masses <sup>2</sup>.</p><h4>Treatment and prognosis</h4><p>There are society guideline recommendations for the imaging follow-up of both ground glass and solid nodules: <a title="Fleischner Society pulmonary nodule recommendations" href="/articles/fleischner-society-pulmonary-nodule-recommendations-1">Fleischner Society guidelines</a> <sup>3</sup>.</p>

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