0 1992 Elsevier Science Publishers
of Rndiologv. I4 ( 1992) 178- 180 B.V. All rights reserved. 0720-048X/92/$05.00
Askin tumor: three case histories and a review of the literature M. Fink’, J. Salisbury2 and P. Gishen’ ‘Department of Clinical Radiology and 2Pathology, King’s College Hospital, London,
199 1; accepted after revision 12 November
Key words: Askin tumor, radiography
Introduction Malignant peripheral neuro-ectodermal tumors (MPNET) of the thoracopulmonary region (Askin tumors) are rare tumors in children and young adults [ l-41. They are part of the spectrum of the small roundcell tumors of bone in children and adolescents. Their clinical and radiologic features are non-specific, and the diagnosis has to be established histo-pathologically, using light-microscopic, ultrastructural and immunocytochemical criteria. Askin tumors are true round cell sarcomas of bone that may or may not contain glycogen as determined by periodic-acid Shiff stain and without diastase. Case reports Case 1 A 5-year-old Caucasian boy presented with a 3 day history of a tender swelling in the left axilla. On examination he had a 3.0 x 2.0 cm smooth, firm mass on the left chest wall. Laboratory investigations were normal. A chest radiograph and CT (Fig. 1) showed an opacity in the left hemithorax with partial destruction of the sixth rib and an associated extra-thoracic soft-tissue mass extending into the chest and compressing the underlying lung. An isotope bone scan confirmed that no other skeletal site was involved. Open biopsy revealed a large friable bloody tumor, which histologically was composed of small dark cells which contained minimal
Address for reprints: Dr. P. Gishen, Department of Clinical Radiology King’s College Hospital, Denmark Hill, London, SE5 9R.3, U.K.
glycogen and immunocytochemically were strongly positive for NSE. Electron microscopy showed scattered dense core granules. This established the diagnosis of Askin tumor. The patient was treated with chemotherapy, with regression of the soft-tissue mass. The primary tumor was resected, including ribs five and seven. At the time of completing chemotherapy a chest radiograph showed regional recurrence with a left hilar mass. He died a few months later with progressive disease of his left fourth and eighth ribs, eighteen months after his initial presentation. Case 2 A 24-year-old Caucasian woman presented with a 2 month history of increasing dyspnoea and malaise, and 2 weeks of dull left-sided chest pain. On examination she had signs of a large left-sided pleural effusion (Fig. 2a). Her white blood cell count was raised at 11.5 x 109/1. The pleural fluid was drained leaving some persistent pleural shadowing. Over the next month the effusion continued to recur. A CT scan (Fig. 2b) 1 month after presentation showed a softtissue density mass almost filling the left hemithorax and displacing the mediastinum to the right. There was no longer any significant amount of pleural fluid. The mass extended through the hemidiaphragm into the upper abdomen (Fig. 2~). An open pleural biopsy showed a small cell tumor which stained negative for glycogen but immunocytochemically positive for the neuroendocrine marker PGP 9.5. The diagnosis of Askin tumor was made. The patient was treated with chemotherapy with initial tumor resolution, but died 13 months after presentation
Fig. 1. Case 1. CT thorax showing the left intra and extra-thoracic
masses and partial destruction
of the sixth left rib.
Fig. 2. (a) Case 2. Chest radiograph at presentation showing large left pleural effusion. (b) One month after presentation. CT thorax showing soft-tissue mass in the left hemithorax with mediastinal shift to the right and compression of the left main bronchus. (c) CT abdomen showing the abdominal extension of the thoracic mass.
with recurrent stases.
Case 3 A 21-year-old caucasian woman presented with a 1 day history of pleuritic left lower chest pain and a 1 month history of intermittent left-sided abdominal pain. She had a mild pyrexia and decreased breath sounds at the left base. Laboratory investigations revealed a raised white blood cell count of 15.1 x 10 l’jl. A chest radiograph (Fig. 3a) showed a rounded opacity in the left lower lobe with no evidence of volume loss. A provisional diagnosis of pneumonia was made and the patient was discharged on antibiotics. Three weeks later the radiological appearances had worsened.
Fig. 3. Case 3. (a) Chest radiograph at presentation showing lobulated mass in left hemithorax. (b) CT thorax 3 weeks after chemotherapy showing posterior soft-tissue mass.
Ultrasound examination of the left chest revealed a small amount of pleural fluid and a solid posterior lobulated intra-thoracic mass. CT scan (Fig. 3b) showed a mass in the posterior lower left hemithorax, up against and abutting the pleura. Percutaneous Tru-Cut needle biopsy was performed under fluoroscopic control one month after presentation. Histologic examination showed a small cell tumor which stained positive for NSE, thus establishing the diagnosis of Askin tumor in the clinical context. The patient has been started on chemotherapy with good response after three treatments. Discussion The Askin tumor forms a separate clinicopathologic entity. Three series [ 1,3,4] document its clinical and radiologic features. It occurs in young people, predominantly children (age range: 4 months to 33 years). Females are affected more commonly (77%). It presents with pain (50x), a chest wall mass (47%) or both. The patient may be dyspnoeic (20 %) or have a fever (17 7;). The prognosis to date is poor. Radiologically the most common finding is pleural disease, either fluid or tumor (70%) A chest wall softtissue mass is seen in 40%. Rib involvement is documented in 37 %. Peripheral intrapulmonary mass is seen in 27%) of which half have associated pleural disease [ 1,41. Tumor spread into the hilum and mediastinum, calcification within the soft-tissue mass, or a paraspinal soft-tissue mass as the sole presenting feature are rarer manifestations. Recurrent disease is most common in the thorax and
skeleton (57% show local recurrence or pulmonary metastases, 27 y0 distal skeletal spread). Abdominal disease which is thought to be due to contiguous spread through the diaphragm is shown in 13%. Pathologically, Askin tumor falls into the category of small round cell sarcomas of bone. Whether Askin tumors arise in bone or soft tissue is unclear, nevertheless almost all show rib involvement histologically. It is our belief that, although rare, Askin tumor is being underdiagnosed. A recent radiological series of 27 primary rib tumors in children [ 131 documented 22 cases of primary malignant rib tumors, all small round cell tumors, of which 20 were classified as Ewing’s sarcoma and two as ‘reticulosarcoma’. The possible diagnosis of Askin tumor was not considered. In this report we mean to make the radiologists aware of the thoracopulmonary manifestations of this condition.
References Fink IJ, Kurtz DW, Cazenove L, Leiber MR, Miser JS, Chandra R, Triche TJ. Malignant thoracopulmonary small cell (‘Askin’) tumor. AJR 1985; 145: 517-520. Singleton EP, Askin tumor, Society of Radiology Film Panel Cases. Pediatric Radio1 1990; 20: 372-373. Saifuddin A, Robertson RJH, Smith SEW The radiology ofAskin tumors. Clin Rad 1991; 43: 19-23. Askin FB, Rosai J, Sibley RK, Dehner LP, McAlister WH. Malignant small cell tumor of the thoracopulmonary region in childhood. Cancer 1979; 43: 2438-2451. Linnoila RJ, Tsokos M, Trich TJ, Marangos PJ, Chandra RS. Evidence for neural origin and PAS positive variants of the malignant small ceil tumor of the thoraco-pulmonary region (‘Askin tumor’). Am J Surg Path01 1986; 10: 124-133. Pinto A, Grant LH, Hayes FA, Schell MJ, Parham DM. Immunohistochemical expression of neuro-specific enolase and Leu-7 in Ewing’s sarcoma of bone. Cancer 1989; 64: 1266-1273. Kozlowski K, Campbell J, Morris L, Sprague P, Taccone A, BelutIi G, Marcinski A, Porta F, Stevens M. Primary rib tumors in children (report of 27 cases with short literature review) Australas Radio1 1989; 33: 210-222.