Primary pleural liposarcoma: a rare differential for an opaque hemithorax
- 1 Pulmonary Medicine, All India Institute of Medical Sciences, Rishikesh, Rishikesh, India
- 2 Pathology & Laboratory Medicine, All India Institute of Medical Sciences, Rishikesh, Rishikesh, India
- Correspondence to Dr Mayank Mishra; virgodrmayank@gmail.com
Abstract
Primary pleural liposarcoma (PPL) is a rare primary malignant pleural tumour originating from primitive mesenchymal tissue. We report the case of a 25-year-old man with a 6-week history of shortness of breath, cough, chest pain and hoarseness of voice. Chest X-ray showed a left opacified hemithorax, and thoracic CT scan revealed a large, heterogeneous, hypodense mass in the left hemithorax. The patient was taken up for ultrasound-guided core biopsy of the mass lesion, and histopathological examination revealed the diagnosis as a pleomorphic variant of PPL. We highlight the importance of considering PPL as a differential diagnosis in cases of large hemithoracic masses.
Background
Metastases are the most commonly encountered malignant pleural pathologies. Primary pleural malignancies constitute a mere 10% of all malignant pleural lesions, of which the most common is malignant pleural mesothelioma (MPM) (90%). The rest comprises rare primary malignant tumours of the pleura, like pleural lymphoma and sarcomas including primary pleural liposarcoma (PPL). PPL usually originates from primitive mesenchymal cell rests and alternatively rarely by the malignant transformation of a pre-existing pleural lipoma. PPLs are extremely rare tumours, and their exact incidence is unknown.1 The most commonly reported type of PPL is the myxoid variant.2 Radiological features may be the basis for suspicion of PPL as a differential diagnosis, but they are often non-specific and overlap with teratomas and hamartomas. Histopathology is mostly diagnostic.
Case presentation
A 25-year-old, previously healthy man from Northern India without any significant occupational exposure, presented to us with a 6-week history of dry cough, hoarseness of voice, left-sided dull aching, non-radiating chest pain and progressive shortness of breath. He was a non-smoker, non-alcoholic and student by occupation. General examination was remarkable for tachypnoea, tachycardia and clubbing, while respiratory examination revealed fullness of the left hemithorax with mediastinal shift to right. Vocal fremitus was absent on the left side, percussion note was dull and no breath sounds were audible on auscultation.
Investigations
Subsequent evaluation with chest X-ray posteroanterior view (figure 1) showed a homogeneously opacified left hemithorax with gross shift of mediastinum to the right, suggesting the clinicoradiological possibility of a massive left-sided pleural effusion. However, screening bedside thoracic ultrasonography (USG) revealed a large, heterogeneous, vascular, hypoechoic mass lesion within the left hemithorax. The patient subsequently underwent a contrast-enhanced CT scan of thorax (figure 2) that revealed a 13×18×23 cm heterogeneous, low attenuation solid lesion in the left hemithorax with mass effect, ipsilateral complete lung collapse and contralateral mediastinal shift. A whole-body positron emission tomography-non-contrast CT scan (figure 3) identified fluorodeoxyglucose avidity (maximum standardised uptake value ~3.3) of the mass lesion, but no other extrathoracic lesions were noticed. The patient subsequently underwent a USG-guided core needle biopsy from the mass, which on histopathological examination was reported as pleomorphic liposarcoma (figure 4). The immunohistochemistry (IHC) panel was negative for S-100 and pan-cytokeratin, whereas the Ki67 index was 40%.
Chest X-ray posteroanterior view showing a homogeneously opacified left hemithorax with gross contralateral mediastinal shift.
Axial (A) and coronal (B) sections of contrast-enhanced CT scan of thorax showing a large heterogeneous low-attenuation solid mass lesion (13×18x23 cm). No foci of calcification is seen within. Collapsed left lung is clearly seen to be circumscribed by the mass, suggesting pleural origin. Multiple hyperdense areas (~56 HU) are seen within the mass, suggestive of haemorrhage. There is an obvious mediastinal shift to the right, and fat planes are preserved with the chest wall. Lesion is, however, abutting the great vessels with loss of fat planes.
Coronal section of whole-body positron emission tomography-non-contrast CT scan showing fluorodeoxyglucose (FDG)-avid (maximum standardised uptake value ~3.3), large, mixed density heterogeneously enhancing mass lesion in left hemithorax measuring 14×18x24 cm. There is loss of fat planes with arch of aorta, mediastinum and left pulmonary vein. No other abnormal FDG-avid lesion was seen in the rest of the body.
Sections examined show cores of tumour tissue with adjacent fibroadipose stroma (A; 20×; H&E). The tumour is composed of sheets of pleomorphic cells, some medium sized with pale eosinophilic cytoplasm and many large cells (B; 100×; H&E) (lipoblasts) with multivacuolated cytoplasm indenting the enlarged and hyperchromatic nuclei (arrows; C and D; 400×; H&E). Many of these lipoblasts are bizarre (circle; C and D; 400×; H&E).
Differential diagnosis
Though not a common age of presentation, a differential diagnosis of solitary fibrous tumour (SFT) of pleura was kept in view of the large size of the mass and no evidence of distant metastasis. However, SFT was definitively ruled out in the histopathological examination.
Treatment
The case was discussed in the institutional tumour board wherein a plan for surgical excision of the tumour was abandoned in view of loss of fat planes with arch of aorta. Instead, administration of neoadjuvant chemotherapy followed by reassessment of resectability was decided upon. Accordingly, the patient was given an appointment for chemotherapy on a day-care basis and was discharged on home oxygen therapy.
Outcome and follow-up
Two days later, however, the patient presented to our emergency department with an acute, sudden worsening of breathlessness and increased chest pain. The patient collapsed shortly after admission to our emergency department before a comprehensive evaluation of his acute worsening could be done.
Discussion
The first case of PPL was reported way back in 1942 by Ackerman and Wheeler. Among the less than 20 documented cases of PPL in literature, it was found to occur more commonly in males, with the myxoid variety being the commonest.3 Pleural neoplasms are usually secondaries from a primary tumour in the breast, lung or gastrointestinal tract. Malignant primary pleural neoplasms constitute about 10% of all pleural tumours, and MPM is the most common tumour in this group (90%).4 Primary pleural sarcomas are rare and include liposarcoma, synovial sarcoma, malignant fibrous histiocytoma, primary neuroectodermal tumour, angiosarcoma, chondrosarcoma, osteosarcoma and leiomyosarcoma.5
PPLs are believed to originate from residual primitive mesenchymal tissue rests. Alternative hypotheses suggest that pre-existing pleural lipomas, parietal pleural adipose tissue or subpleural fat can rarely undergo malignant transformation leading to the formation of PPL.4 5
Liposarcomas are classified on a histological basis into well-differentiated, myxoid, pleomorphic and dedifferentiated subtypes, according to the WHO. The first two subtypes have a better prognosis, with a 5-year survival of 71% as compared to 12.5% for the latter two subtypes.3 5 The pleomorphic and de-differentiated subtypes more often present with locally advanced or metastatic disease.6
Because of its slow growth within the pleural cavity, patients with PPL may remain asymptomatic for an extended period of time. Clinical manifestations are hence often delayed or non-specific and are usually related to displacement and/or compression of adjacent anatomical structures. Macroscopically, PPL is usually nodular or lobular and has a gelatinous appearance.4
The pleomorphic variant of PPL is a histopathological diagnosis clinched by identifying pleomorphic lipoblasts. Sometimes, multiple tissue samples may be required to identify the areas of interest which may be missed on core needle biopsies. The pleomorphic lipoblasts have bizarre nuclei with nuclear indentations caused by the cytoplasmic lipid droplets.7
Complete surgical excision with adjuvant radiotherapy is the treatment of choice for PPL that is devoid of signs of local invasion and deemed resectable as per radiology.5 For unresectable cases, palliative chemotherapy and radiotherapy are the preferred modalities of treatment.8
Learning points
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A homogeneously opaque hemithorax should not always be assumed to be a massive pleural effusion without confirmation on ultrasonography and/or CT imaging.
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Large pleural-based or parenchymal thoracic masses may act as clinicoradiological mimics of effusion and hence must be carefully evaluated with thorough imaging and detailed tissue sampling.
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Primary pleural liposarcoma is one such rare tumour of pleural origin that must be considered in the work-up of suspected mass lesions producing an opaque hemithorax.
Ethics statements
Patient consent for publication
Footnotes
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Contributors Clinical data acquisition, literature review and initial manuscript draft: AL, AR. Manuscript editing, review, proof-reading and guarantor: MM. Histopathology and related literature review: PJ.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
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