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Journal of Case Reports
Primary Pulmonary Primitive Neuroectodermal Tumor with CNS Metastasis
Vijayasree Mandava, Bora Sreedhar, Ramana Kumari Pasam, G. Saila Bala
From the Department of Pathology, Guntur Medical College, Guntur, Andhra Pradesh, India.
Corresponding Author:
Dr. M.Vijaya Sree
Email: vijayasree123456@gmail.com
Received: 19-DEC-2014 Accepted: 23-DEC-2014 Published Online: 25-DEC-2014
DOI: http://dx.doi.org/10.17659/01.2014.0129
Abstract
We describe a rare case of primitive neuroectodermal tumor (PNET) originating in the lung of a 20 year old male. A lung mass was detected on a chest radiograph showing opacity with pleural effusion. CT thorax showed mediastinal mass while hypodense mass was seen in right parietal convexity of brain in CT brain. We received multiple grey brown to dark brown friable masses largest of size 13x11x5 cm and other small masses altogether measuring 16x5x8 cm. Cut sections of all masses were grey white and hemorrhagic. Primary pulmonary PNET was reported on histopathology with CNS biopsy also showing similar appearance. 
Keywords : Bone Neoplasms, Neuroectodermal Tumors, Brain, Sarcoma, Pleural Effusion, Humans.
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Introduction

A peripheral primitive neuroectodermal tumor (PNET) is a malignant tumor that usually occurs in bones and soft tissues during childhood or adolescence. PNET constitutes a family of malignant neoplasms comprising small, undifferentiated neuroectodermal cells. PNET tumors arising in the thoracopulmonary region are commonly referred to as Askin tumour [1,2]. A PNET originating in the lung parenchyma is extremely rare and to our knowledge only few cases have been described in practice. We report an aggressive and rapid progressive case of primary pulmonary PNET with CNS metastasis.

Case Report

A 20 year old male was admitted with complaints of chest pain and dyspnoea since 10 days. The chest pain was retrosternal in location and it was  non-radiating nor related to the meals. This was accompanied by headache and  sudden onset weakness in the left upper limb and lower limb. He also had a history of sudden collapse, 1 month prior to admission. He was a non-smoker and non-alcoholic. He was apparently in good health and reported that he had no systemic disease. On examination it was found he was an averagely built person and had neither clubbing nor lymphadenopathy. Also, all the routine investigations were found to be in the normal limits.

His chest X-ray showed opacity with pleural effusion in right lung. His CT chest showed mediastinal mass with right pleural based lesions [Fig.1a,b]. Moderately enhancing extra-axial hypodense mass lesion in right parietal convexity with midline shift towards left was seen in CT brain [Fig.2a,2b]. Pleural fluid cytology revealed lymphocytes and reactive mesothelial cells. The differential diagnosis of thymic carcinoma, neuroendocrine carcinoma, malignant lymphoma and hemangioendothelioma were considered.


The patient was taken up for thoracotomy with excision of the tumor. Intraoperatively, it was observed that there was a large mass in the mediastinum with invasion of great vessels and mediastinal lymphnodes. Hence the tumor debulking was done to the extent possible. Complete excision of the tumor could not be done as it was infiltrating the great vessels and pericardium.

We received multiple grey brown to dark brown friable mediastinal masses largest of size 13x11x5 cm and other small masses all together measuring 16x15x8 cm. Cut section of all masses were found to be grey white and hemorrhagic [Fig.3]. The neoplasm was composed of sheets and cords of small hyperchromatic cells with round to oval nuclei containing coarsely granular chromatin and indistinct nucleoli showing scanty cytoplasm. A few Homer-Wright rosettes were also observed with extensive necrosis [Fig.4a-c].


Panel of IHC markers like CD34, LCA, chromogranin, cytokeratin and EMA [Fig.5a] were done which were all found to be negative except CD99 [Fig.5b] which showed rich positivity. Our final diagnosis was primary pulmonary primitive neuroectodermal tumor extending to mediastinum with metastasis into CNS in view of microscopic and immunohistochemistry of the specimen along with CD99 positivity.


Discussion

PNET are rare tumors occurring in the posterior sulcus or chest wall of adolescent or young adult patients. They are believed to develop from the peripheral nerves such as intercostal nerves. Lesions of PNET are typically painful. Invasive thoracic tumors may either develop or invade on the chest wall, lung or mediastinum [3]. They are generally soft and fleshy with hemorrhagic and necrotic areas. These tumors were classified by Askin and Colleagues as thoracic autonomic neurogenic tumors. A similar chromosomal translocation occurring in both Ewings sarcoma and PNET lesions suggest that those tumors are closely related. Typically, Askin tumour develops as a solitary mass or multiple masses in the thoracic area [4]. In thoracic area, these tumors are invasive and prone to destroying bone. Once resected, they recur with extremely high frequency. The most common recurrence sites are the skeleton and CNS. Characteristic PNET pathological findings include compact nests of small cells and Homer-Wright pseudorosettes with an acidophilic core of neurofibrillary character [5,6]. An abnormality of chromosome 22 (e.g., reciprocal translocation of the long arms of chromosomes 11 and 22 or deletion of the long arm of 22) is characteristically present [7].

Primitive neuroectodermal tumour lesions are aggressive and are usually lethal. Once diagnosis of PNET has been made, early wide excision of the tumor along with multimodality chemotherapy and radiotherapy should be undertaken to offer any hope of a long term cure.

The present case describes one of the few reported cases of PNET in an adult. It is unusual for the age of presentation and short duration of unique symptom that is acute onset thoracic pain. Plain chest radiograph and CT scan were diagnostic for pulmonary tumor. Open thoracotomy with excision of the removable tumor proves the diagnosis of PNET. The tumor had invaded the great vessels in the thorax and the mediastinal lymph nodes due to the advanced nature of the tumor.

In summary, we have described a rare example of primary pulmonary PNET which was suggested by a large, heterogenous, enhanced, unilateral lung mass with amorphous calcification and was confirmed by a generous biopsy that yielded an adequate specimen for pathological diagnosis.

References
  1. Askin FB, Rosai J, Sibley RK, Dehner LP, Mc Alister WH. Malignant small cell tumour of the thoracopulmonary region in childhood. Cancer. 1979;43:2438-2451.
  2. Shamberger RC, Jarbell NJ, Perez-Atayde AR, Grier HE. Malignant small round cell tumour. (Ewing’s- PNET) of the chest wall in children. J Pediatr Surg. 1994;29:179-185.
  3. Bourque  MD, DiLorenzo M, Collin PP, Russo P, Laberge JM, Moir C. Malignant small cell tumour of the thoraco pulmonary region (Askin tumour). J Pediatr Surg. 1989;24:1079-1083.
  4. Sawin RS, Conrad EU, Park JR, Waldhausen JHT. Preresection chemotherapy improves survival for children with Askin tumours. Arch Surg. 1996;131:877-880.
  5. Kushner BH, Hajdu SI, Gulati SC, et al. Extracranial primitive neuroectodermal tumors: the Memorial sloan-Kettering cancer center experience. Cancer. 1991;67:1825-1829.
  6. Cavazzana AO, Ninfo V, Roberts J, et al. Perpiheral neural epithelioma: a light microscopic, immunocytochemical and ultrastructural study. Mod Pathol. 1992;5:71.
  7. Ambros IM, Ambros PF, Sibley RK, et al. MIC2 is a specific marker for Ewing’s sarcoma and PNET. Cancer. 1991;67:1886.
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Mandava V, Sreedhar B, Pasam RK, Bala GSPrimary Pulmonary Primitive Neuroectodermal Tumor with CNS Metastasis.JCR 2014;4:508-511
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Mandava V, Sreedhar B, Pasam RK, Bala GSPrimary Pulmonary Primitive Neuroectodermal Tumor with CNS Metastasis.JCR [serial online] 2014[cited 2024 Mar 19];4:508-511. Available from: http://www.casereports.in/articles/4/2/Primary-Pulmonary-Primitive-Neuroectodermal-Tumor-with-CNS-Metastasis.html
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