Chest imagingCase Type
David Annan , Sanjay Karamsadkar , Luis Beltran , Rohit Malliwal 
 St Bartholomew's Hospital and The Royal London Hospital, Department of Imaging, Barts Health NHS Trust, London, United Kindgdom
 The Royal London Hospital, Department of Pathology, Barts Health NHS Trust, London, United KingdomPatient
28 years, female
A 28-year-old female patient presented with a three month history of breathlessness, and a two week history of pleuritc chest pain, orthopnoea, cough, nausea and weight loss. She was a non-smoker with no history of fever or night sweats. No significant family or past medical history was ascertained.
A chest radiograph performed on admission demonstrated a large area of dense opacification within the left hemithorax with associated tracheal and mediastinal shift to the contralateral side. There was a small volume left-sided pleural effusion. The right lung and pleural spaces were clear.
A subsequent contrast-enhanced CT (Computed Tomography) study of the chest was performed which demonstrated a very large pulmonary mass which occupied the majority of the left lung, with some sparing of the left upper lobe. It was composed of soft tissue with foci of macroscopic fat, fluid-attenuation cystic areas and multiple foci of calcification. The CT confirmed the degree of mediastinal shift and the presence of a small left pleural effusion. There were no size-significant mediastinal lymph nodes, no associated osseous lesions and no extrapulmonary extension. The appearances of the findings were in keeping with a large mature intrapulmonary teratoma which was histologically confirmed.
Mature teratomata are tumours consisting of tissues that are derived from more than one germ cell line . They are the most common histological type of germ cell tumours, followed by seminomas, characteristically found in the gonads . The most likely extra-gonadal site is within the anterior mediastinum. Pulmonary teratomata are rare , first described in the literature by Mohr in 1839 , and not commonly seen in clinical practice . Much like a teratoma of the anterior mediastinum, intrapulmonary (and endobronchial) teratomata arise from the third pharyngeal pouch . Pulmonary teratomata are classified as either parenchymal or endobronchial lesions, with the majority of those seen falling into the former category, as is the case here . They typically involve the upper lobe of the left lung , the reason for which is not certain.
Patients typically present in the second to fourth decade , with the common presenting symptoms being chest pain, cough, haemoptysis, and trichoptysis, the latter being the most specific symptom as it signifies communication with a bronchus [4, 5].
CT is the ideal imaging modality for these patients given its ability to characterise the soft tissue components of a teratoma and ability to determine if it has ruptured . This distinction is pivotal in surgical planning as rupture induces inflammation and adhesions to adjacent anatomical structures.  Surgical resection is the mainstay of treatment and is recommended due to the complications associated with growth and mass effect of the tumour: life-threatening haemoptysis due to invasion into the adjacent airways and bronchial vessels can lead to haemothorax, lung collapse and / or infection [4 - 6]. Although these are typically benign tumours, they are thought to have malignant potential in approximately a third of cases [1, 4], and can transform into sarcomas . These transformations pose a diagnostic challenge as transformation may be restricted to a focal area of the teratoma, and may only affect one of the tissue components that otherwise appear benign on imaging . This important clinical distinction is necessary as pulmonary teratomata with malignant transformation are resistant to chemotherapy and radiotherapy [3, 7].
Take Home Message:
An intrapulmonary teratoma, although rare, is an important diagnosis to consider in younger patients who present with breathlessness and masses on chest radiographs.
Written informed patient consent for publication has been obtained.
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