CASE 18602 Published on 03.07.2024

Chronic pulmonary consolidations: Discriminating invasive mucinous adenocarcinoma

Section

Chest imaging

Case Type

Clinical Case

Authors

Rocío Martín Márquez 1, Eduardo Gutiérrez Dorta 2, Benito Fernández Ruiz 1

1 Radiodiagnosis Service, Hospital Universitario Reina Sofía, Córdoba, Spain

2 Radiodiagnosis Service, Complexo Hospitalario Universitario de Ourense, Ourense, Spain

Patient

61 years, female

Categories
Area of Interest Thorax ; Imaging Technique CT
Clinical History

A 61-year-old woman, active smoker, diagnosed with SARS-CoV-2 infection three months ago. Since then, she has been experiencing symptoms of dyspnoea, productive cough and chest pain. Chest X-ray shows persistent bilateral infiltrates that have worsened despite antibiotic treatment.

Imaging Findings

A non-contrast chest CT scan was performed, revealing a large consolidation involving almost the entire right lower lobe (Figure 1), with poorly defined borders, extending towards the pulmonary hilum, encompassing and narrowing the bronchi of the right lower lobe (Figure 2). Additionally, smaller consolidations are seen in the left lower lobe and lingula, accompanied by a ground-glass halo (Figure 3). Multiple subcentimeter pulmonary nodules are noted bilaterally (Figure 4). Smooth septal thickening and centrilobular emphysema, predominantly in the upper lobes, are also observed. No pleural effusion is noted, but there is a layer of pericardial effusion. Despite being a non-contrast study, slightly enlarged mediastinal lymph nodes are visualised (Figure 5).

Discussion

Invasive mucinous adenocarcinoma, also referred to as pneumonic-type adenocarcinoma, is a primary lung neoplasm that often manifests in a multicentric, extensively and bilaterally affected manner. This presentation is likely influenced by tumoural dissemination through the airway [1].

Its consolidative form may be indistinguishable from a bronchopneumonic process. Key diagnostic points include the patient’s clinical presentation: absence of fever, antibiotic refractoriness, and in some cases, a disconnect between the patient’s limited or absent infectious symptoms and extensive lung involvement [2]. In the case of infectious pneumonia, patients will often associate analytical alterations such as leukocytosis, elevated c-reactive protein or elevated procalcitonin.

The radiological presentation of mucinous adenocarcinoma includes single or multiple nodules, consolidations, and a combination of nodules, ground-glass opacities, and consolidations, with a predilection for the lower lobes in all forms.

Another characteristic is the arrangement of bronchi within the tumour lesions—narrowed, with an increased angle of branching and distally truncated (the “tree-in-bud” sign) [3]. These alterations can help differentiate these consolidations from pneumonia.

Acinar nodules are a distinctive feature of this tumour type, characterised by their density and relatively well-defined borders, reflecting acinar and alveolar occupation by mucus and mucin-laden tumour cells.

Mucinous adenocarcinoma manifests as a consolidation affecting more than half of a lobe and is more frequently accompanied by fissure bulging, consolidation hypodensity, airspace lesions, CT angiogram sign, other coexisting nodules, pleural effusion, and adenopathy. On the other hand, other adenocarcinoma variants with a pneumonic appearance, especially the acinar-predominant type, affect less than 50% of a lobe and are accompanied by fissural retraction [4].

In pneumonic-type adenocarcinomas with a localised pattern of involvement, the TNM classification will be applied in the same way as for other lung cancer subtypes. In case of a more diffuse pattern of involvement, T and M categories are assigned according to the extent of the affected areas (T3 for involvement confined to one lobe, T4 for unilateral involvement of more than one lobe, and M1a in case of bilateral involvement) [6].

It should be noted that non-mucinous adenocarcinomas may also present as pseudopneumonic consolidations.

The main differential diagnosis should be established with infectious processes, inflammatory conditions (cryptogenic organised pneumonia), and neoplasms (lymphoma)[5].

Take Home Message

In patients with chronic consolidative processes who exhibit subtle symptoms and lack of response to antibiotic therapy or other treatments, it is crucial to consider the possibility of pulmonary adenocarcinoma as a potential diagnosis.

Informed consent for publication has been obtained.

Differential Diagnosis List
Bronchopneumonia
Invasive mucinous adenocarcinoma
Lymphoma
Alveolar sarcoidosis
Cryptogenic organising pneumonia (COP)
Alveolar proteinosis
Eosinophilic pneumonia
Final Diagnosis
Invasive mucinous adenocarcinoma
Case information
URL: https://www.eurorad.org/case/18602
DOI: 10.35100/eurorad/case.18602
ISSN: 1563-4086
License