In 1921, James Ewing reported a rare type of sarcoma in children, adolescents, and young adults that is a highly malignant tumor of the bone and soft tissue, composed of small round cells . Separately, Stout et al. reported in 1918 that a PNET is an ulnar nerve-derived small round cell tumor with rosette formation that develops in soft tissues in young individuals . The first small round cell tumor of chest wall origin was reported in a pediatric patient by Askin, and these tumors are referred to as Askin tumors . An Askin tumor is a PNET that develops from the soft tissues of the chest wall in childhood. At that time, our case might have been termed an Askin tumor.
Pathologically, EWS/PNET is composed of small, round, uniform cells with characteristic small-sized rosette formation. These tumors, both with a poor prognosis, were described as separate entities in the small round cell tumor group in the second version of the WHO classification published in 1993. However, with recent improvements in molecular biology, a translocation (11; 22) (q24; q12) specific to both EWS and PNET has been identified, and the EWS-FLI-1 fused gene was identified at the cleavage site of this translocation. They therefore were subsequently integrated into a single item (Ewing’s sarcoma/PNET) in the WHO classification, published in 2007 . The ESFT includes EWS of the bone, extraosseous EWS, and PNET of the bone or soft tissue.
The most useful immunohistologic reagent for the diagnosis of ESFT is the monoclonal antibody CD99, which recognizes a cell surface protein. Specimens stain strongly positive with the CD99 antibody in more than 90% to 95% of cases of reported ESFT.
Chest wall ESFT tumors are rare, have a high rate of local recurrence, and frequently are metastatic at presentation. In a report of 84 thoracic PNET cases by Biswas et al., patient age ranged from 3 to 40 years (mean age = 15 years) and tumor diameter ranged from 1.6 to 20.0 cm (mean diameter = 9.0 cm). It occurred most commonly in the ribs (54%), the scapula (25%), and the chest wall (14%), with a male predominance (70%). Twenty-seven (32%) patients had metastatic disease at diagnosis. An independent prognostic factor for PNET is the presence of metastatic disease . The median relapse-free interval (RFI) after treatment was 17 months (range, 5 to 90 months). In contrast to the dramatic improvement in survival for ESFT, the prognosis after recurrent disease remains poor, especially for patients with a RFI of less than 24 months .
The morphologic, immunohistochemical, and molecular biological characteristics from both specimens supported that the second tumor was a local recurrence of an ESFT. Several prior studies established that the longest time until recurrence of ESFT was 19 years . Our case demonstrates the possibility of very late local recurrence of ESFT.
We report a case of locally recurrent ESFT 25 years after initial treatment. To our knowledge, no case with such late local relapse as our case has been reported to date.